Links to Exploration step
Le document en format XML
<record><TEI><teiHeader><fileDesc><titleStmt><title xml:lang="en">Shape Optimization for Additive Manufacturing of Removable Partial Dentures - A New Paradigm for Prosthetic CAD/CAM</title><author><name sortKey="Chen, Junning" sort="Chen, Junning" uniqKey="Chen J" first="Junning" last="Chen">Junning Chen</name><affiliation><nlm:aff id="aff001"><addr-line>School of Aerospace, Mechanical and Mechatronic Engineering, the University of Sydney, Sydney, NSW 2006, Australia</addr-line></nlm:aff></affiliation></author><author><name sortKey="Ahmad, Rohana" sort="Ahmad, Rohana" uniqKey="Ahmad R" first="Rohana" last="Ahmad">Rohana Ahmad</name><affiliation><nlm:aff id="aff002"><addr-line>Unit of Prosthodontics, Faculty of Dentistry, Shah Alam & Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA, Bandar Puncak Alam, Selangor, 42300, Malaysia</addr-line></nlm:aff></affiliation></author><author><name sortKey="Suenaga, Hanako" sort="Suenaga, Hanako" uniqKey="Suenaga H" first="Hanako" last="Suenaga">Hanako Suenaga</name><affiliation><nlm:aff id="aff003"><addr-line>Division of Preventive Dentistry, Tohoku University Graduate School of Dentistry, 4–1 Seiryo-machi, Aoba-ku, Sendai, 980–8575, Japan</addr-line></nlm:aff></affiliation></author><author><name sortKey="Li, Wei" sort="Li, Wei" uniqKey="Li W" first="Wei" last="Li">Wei Li</name><affiliation><nlm:aff id="aff001"><addr-line>School of Aerospace, Mechanical and Mechatronic Engineering, the University of Sydney, Sydney, NSW 2006, Australia</addr-line></nlm:aff></affiliation></author><author><name sortKey="Sasaki, Keiichi" sort="Sasaki, Keiichi" uniqKey="Sasaki K" first="Keiichi" last="Sasaki">Keiichi Sasaki</name><affiliation><nlm:aff id="aff004"><addr-line>Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, 4–1 Seiryo-machi, Aoba-ku, Sendai, 980–8575, Japan</addr-line></nlm:aff></affiliation></author><author><name sortKey="Swain, Michael" sort="Swain, Michael" uniqKey="Swain M" first="Michael" last="Swain">Michael Swain</name><affiliation><nlm:aff id="aff005"><addr-line>Faculty of Dentistry, The University of Sydney, Sydney, NSW 2006, Australia</addr-line></nlm:aff></affiliation></author><author><name sortKey="Li, Qing" sort="Li, Qing" uniqKey="Li Q" first="Qing" last="Li">Qing Li</name><affiliation><nlm:aff id="aff001"><addr-line>School of Aerospace, Mechanical and Mechatronic Engineering, the University of Sydney, Sydney, NSW 2006, Australia</addr-line></nlm:aff></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">PMC</idno><idno type="pmid">26161878</idno><idno type="pmc">4498620</idno><idno type="url">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4498620</idno><idno type="RBID">PMC:4498620</idno><idno type="doi">10.1371/journal.pone.0132552</idno><date when="2015">2015</date><idno type="wicri:Area/Pmc/Corpus">000418</idno><idno type="wicri:explorRef" wicri:stream="Pmc" wicri:step="Corpus" wicri:corpus="PMC">000418</idno></publicationStmt><sourceDesc><biblStruct><analytic><title xml:lang="en" level="a" type="main">Shape Optimization for Additive Manufacturing of Removable Partial Dentures - A New Paradigm for Prosthetic CAD/CAM</title><author><name sortKey="Chen, Junning" sort="Chen, Junning" uniqKey="Chen J" first="Junning" last="Chen">Junning Chen</name><affiliation><nlm:aff id="aff001"><addr-line>School of Aerospace, Mechanical and Mechatronic Engineering, the University of Sydney, Sydney, NSW 2006, Australia</addr-line></nlm:aff></affiliation></author><author><name sortKey="Ahmad, Rohana" sort="Ahmad, Rohana" uniqKey="Ahmad R" first="Rohana" last="Ahmad">Rohana Ahmad</name><affiliation><nlm:aff id="aff002"><addr-line>Unit of Prosthodontics, Faculty of Dentistry, Shah Alam & Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA, Bandar Puncak Alam, Selangor, 42300, Malaysia</addr-line></nlm:aff></affiliation></author><author><name sortKey="Suenaga, Hanako" sort="Suenaga, Hanako" uniqKey="Suenaga H" first="Hanako" last="Suenaga">Hanako Suenaga</name><affiliation><nlm:aff id="aff003"><addr-line>Division of Preventive Dentistry, Tohoku University Graduate School of Dentistry, 4–1 Seiryo-machi, Aoba-ku, Sendai, 980–8575, Japan</addr-line></nlm:aff></affiliation></author><author><name sortKey="Li, Wei" sort="Li, Wei" uniqKey="Li W" first="Wei" last="Li">Wei Li</name><affiliation><nlm:aff id="aff001"><addr-line>School of Aerospace, Mechanical and Mechatronic Engineering, the University of Sydney, Sydney, NSW 2006, Australia</addr-line></nlm:aff></affiliation></author><author><name sortKey="Sasaki, Keiichi" sort="Sasaki, Keiichi" uniqKey="Sasaki K" first="Keiichi" last="Sasaki">Keiichi Sasaki</name><affiliation><nlm:aff id="aff004"><addr-line>Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, 4–1 Seiryo-machi, Aoba-ku, Sendai, 980–8575, Japan</addr-line></nlm:aff></affiliation></author><author><name sortKey="Swain, Michael" sort="Swain, Michael" uniqKey="Swain M" first="Michael" last="Swain">Michael Swain</name><affiliation><nlm:aff id="aff005"><addr-line>Faculty of Dentistry, The University of Sydney, Sydney, NSW 2006, Australia</addr-line></nlm:aff></affiliation></author><author><name sortKey="Li, Qing" sort="Li, Qing" uniqKey="Li Q" first="Qing" last="Li">Qing Li</name><affiliation><nlm:aff id="aff001"><addr-line>School of Aerospace, Mechanical and Mechatronic Engineering, the University of Sydney, Sydney, NSW 2006, Australia</addr-line></nlm:aff></affiliation></author></analytic><series><title level="j">PLoS ONE</title><idno type="eISSN">1932-6203</idno><imprint><date when="2015">2015</date></imprint></series></biblStruct></sourceDesc></fileDesc><profileDesc><textClass></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en"><p>With ever-growing aging population and demand for denture treatments, pressure-induced mucosa lesion and residual ridge resorption remain main sources of clinical complications. Conventional denture design and fabrication are challenged for its labor and experience intensity, urgently necessitating an automatic procedure. This study aims to develop a fully automatic procedure enabling shape optimization and additive manufacturing of removable partial dentures (RPD), to maximize the uniformity of contact pressure distribution on the mucosa, thereby reducing associated clinical complications. A 3D heterogeneous finite element (FE) model was constructed from CT scan, and the critical tissue of mucosa was modeled as a hyperelastic material from <italic>in vivo</italic> clinical data. A contact shape optimization algorithm was developed based on the bi-directional evolutionary structural optimization (BESO) technique. Both initial and optimized dentures were prototyped by 3D printing technology and evaluated with <italic>in vitro</italic> tests. Through the optimization, the peak contact pressure was reduced by 70%, and the uniformity was improved by 63%. <italic>In vitro</italic> tests verified the effectiveness of this procedure, and the hydrostatic pressure induced in the mucosa is well below clinical pressure-pain thresholds (PPT), potentially lessening risk of residual ridge resorption. This proposed computational optimization and additive fabrication procedure provides a novel method for fast denture design and adjustment at low cost, with quantitative guidelines and computer aided design and manufacturing (CAD/CAM) for a specific patient. The integration of digitalized modeling, computational optimization, and free-form fabrication enables more efficient clinical adaptation. The customized optimal denture design is expected to minimize pain/discomfort and potentially reduce long-term residual ridge resorption.</p></div></front><back><div1 type="bibliography"><listBibl><biblStruct><analytic><author><name sortKey="Field, C" uniqKey="Field C">C Field</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author><author><name sortKey="Li, W" uniqKey="Li W">W Li</name></author><author><name sortKey="Thompson, M" uniqKey="Thompson M">M Thompson</name></author><author><name sortKey="Swain, M" uniqKey="Swain M">M Swain</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kydd, Wl" uniqKey="Kydd W">WL Kydd</name></author><author><name sortKey="Daly, Ch" uniqKey="Daly C">CH Daly</name></author><author><name sortKey="Nansen, D" uniqKey="Nansen D">D Nansen</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sawada, A" uniqKey="Sawada A">A Sawada</name></author><author><name sortKey="Wakabayashi, N" uniqKey="Wakabayashi N">N Wakabayashi</name></author><author><name sortKey="Ona, M" uniqKey="Ona M">M Ona</name></author><author><name sortKey="Suzuki, T" uniqKey="Suzuki T">T Suzuki</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Ahmad, R" uniqKey="Ahmad R">R Ahmad</name></author><author><name sortKey="Chen, J" uniqKey="Chen J">J Chen</name></author><author><name sortKey="Abu Hassan, Mi" uniqKey="Abu Hassan M">MI Abu-Hassan</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author><author><name sortKey="Swain, Mv" uniqKey="Swain M">MV Swain</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Mori, S" uniqKey="Mori S">S Mori</name></author><author><name sortKey="Sato, T" uniqKey="Sato T">T Sato</name></author><author><name sortKey="Hara, T" uniqKey="Hara T">T Hara</name></author><author><name sortKey="Nakashima, K" uniqKey="Nakashima K">K Nakashima</name></author><author><name sortKey="Minagi, S" uniqKey="Minagi S">S Minagi</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sato, T" uniqKey="Sato T">T Sato</name></author><author><name sortKey="Hara, T" uniqKey="Hara T">T Hara</name></author><author><name sortKey="Mori, S" uniqKey="Mori S">S Mori</name></author><author><name sortKey="Shirai, H" uniqKey="Shirai H">H Shirai</name></author><author><name sortKey="Minagi, S" uniqKey="Minagi S">S Minagi</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Imai, Y" uniqKey="Imai Y">Y Imai</name></author><author><name sortKey="Sato, T" uniqKey="Sato T">T Sato</name></author><author><name sortKey="Mori, S" uniqKey="Mori S">S Mori</name></author><author><name sortKey="Okamoto, M" uniqKey="Okamoto M">M Okamoto</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Blum, Ir" uniqKey="Blum I">IR Blum</name></author><author><name sortKey="Mccord, Jf" uniqKey="Mccord J">JF McCord</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Carlsson, Ge" uniqKey="Carlsson G">GE Carlsson</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Suzuki, Y" uniqKey="Suzuki Y">Y Suzuki</name></author><author><name sortKey="Katoh, M" uniqKey="Katoh M">M Katoh</name></author><author><name sortKey="Sato, J" uniqKey="Sato J">J Sato</name></author><author><name sortKey="Morokuma, M" uniqKey="Morokuma M">M Morokuma</name></author><author><name sortKey="Hosoi, Ma" uniqKey="Hosoi M">MA Hosoi</name></author><author><name sortKey="Ohkubo, C" uniqKey="Ohkubo C">C Ohkubo</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Ogawa, T" uniqKey="Ogawa T">T Ogawa</name></author><author><name sortKey="Ogimoto, T" uniqKey="Ogimoto T">T Ogimoto</name></author><author><name sortKey="Sumiyoshi, K" uniqKey="Sumiyoshi K">K Sumiyoshi</name></author><author><name sortKey="Koyano, K" uniqKey="Koyano K">K Koyano</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Bae, Kh" uniqKey="Bae K">KH Bae</name></author><author><name sortKey="Kim, C" uniqKey="Kim C">C Kim</name></author><author><name sortKey="Paik, Di" uniqKey="Paik D">DI Paik</name></author><author><name sortKey="Kim, Jb" uniqKey="Kim J">JB Kim</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Wright, Ps" uniqKey="Wright P">PS Wright</name></author><author><name sortKey="Glantz, Po" uniqKey="Glantz P">PO Glantz</name></author><author><name sortKey="Randow, K" uniqKey="Randow K">K Randow</name></author><author><name sortKey="Watson, Rm" uniqKey="Watson R">RM Watson</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Maruo, Y" uniqKey="Maruo Y">Y Maruo</name></author><author><name sortKey="Nishigawa, G" uniqKey="Nishigawa G">G Nishigawa</name></author><author><name sortKey="Irie, M" uniqKey="Irie M">M Irie</name></author><author><name sortKey="Oka, M" uniqKey="Oka M">M Oka</name></author><author><name sortKey="Hara, T" uniqKey="Hara T">T Hara</name></author><author><name sortKey="Suzuki, K" uniqKey="Suzuki K">K Suzuki</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Bail, M" uniqKey="Bail M">M Bail</name></author><author><name sortKey="Meister, Lmb" uniqKey="Meister L">LMB Meister</name></author><author><name sortKey="Campagnoli, Eb" uniqKey="Campagnoli E">EB Campagnoli</name></author><author><name sortKey="Jorge, Jh" uniqKey="Jorge J">JH Jorge</name></author><author><name sortKey="Ban, Mdci" uniqKey="Ban M">MdCI Ban</name></author><author><name sortKey="Sanchez Ayala, A" uniqKey="Sanchez Ayala A">A Sanchez-Ayala</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Lee, C J" uniqKey="Lee C">C-J Lee</name></author><author><name sortKey="Bok, S B" uniqKey="Bok S">S-B Bok</name></author><author><name sortKey="Bae, J Y" uniqKey="Bae J">J-Y Bae</name></author><author><name sortKey="Lee, H H" uniqKey="Lee H">H-H Lee</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Rodrigues, Rcs" uniqKey="Rodrigues R">RCS Rodrigues</name></author><author><name sortKey="Faria, Acl" uniqKey="Faria A">ACL Faria</name></author><author><name sortKey="Macedo, Ap" uniqKey="Macedo A">AP Macedo</name></author><author><name sortKey="De Mattos, Mdgc" uniqKey="De Mattos M">MdGC de Mattos</name></author><author><name sortKey="Ribeiro, Rf" uniqKey="Ribeiro R">RF Ribeiro</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Hyde, Tp" uniqKey="Hyde T">TP Hyde</name></author><author><name sortKey="Craddock, Hl" uniqKey="Craddock H">HL Craddock</name></author><author><name sortKey="Blance, A" uniqKey="Blance A">A Blance</name></author><author><name sortKey="Brunton, Pa" uniqKey="Brunton P">PA Brunton</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Lawson, Wa" uniqKey="Lawson W">WA Lawson</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kanbara, R" uniqKey="Kanbara R">R Kanbara</name></author><author><name sortKey="Nakamura, Y" uniqKey="Nakamura Y">Y Nakamura</name></author><author><name sortKey="Ochiai, Kt" uniqKey="Ochiai K">KT Ochiai</name></author><author><name sortKey="Kawai, T" uniqKey="Kawai T">T Kawai</name></author><author><name sortKey="Tanaka, Y" uniqKey="Tanaka Y">Y Tanaka</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Archangelo, Cm" uniqKey="Archangelo C">CM Archangelo</name></author><author><name sortKey="Rocha, Ep" uniqKey="Rocha E">EP Rocha</name></author><author><name sortKey="Pereira, Ja" uniqKey="Pereira J">JA Pereira</name></author><author><name sortKey="Martin Junior, M" uniqKey="Martin Junior M">M Martin Junior</name></author><author><name sortKey="Anchieta, Rb" uniqKey="Anchieta R">RB Anchieta</name></author><author><name sortKey="Freitas Junior, Ac" uniqKey="Freitas Junior A">AC Freitas Junior</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Muraki, H" uniqKey="Muraki H">H Muraki</name></author><author><name sortKey="Wakabayashi, N" uniqKey="Wakabayashi N">N Wakabayashi</name></author><author><name sortKey="Park, I" uniqKey="Park I">I Park</name></author><author><name sortKey="Ohyama, T" uniqKey="Ohyama T">T Ohyama</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Li, W" uniqKey="Li W">W Li</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author><author><name sortKey="Steven, Gp" uniqKey="Steven G">GP Steven</name></author><author><name sortKey="Xie, Ym" uniqKey="Xie Y">YM Xie</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Li, W" uniqKey="Li W">W Li</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author><author><name sortKey="Steven, Gp" uniqKey="Steven G">GP Steven</name></author><author><name sortKey="Xie, Ym" uniqKey="Xie Y">YM Xie</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Li, W" uniqKey="Li W">W Li</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author><author><name sortKey="Steven, Gp" uniqKey="Steven G">GP Steven</name></author><author><name sortKey="Xie, Ym" uniqKey="Xie Y">YM Xie</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author><author><name sortKey="Steven, Gp" uniqKey="Steven G">GP Steven</name></author><author><name sortKey="Querin, Om" uniqKey="Querin O">OM Querin</name></author><author><name sortKey="Xie, Ym" uniqKey="Xie Y">YM Xie</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Chang, Cc" uniqKey="Chang C">CC Chang</name></author><author><name sortKey="Lee, My" uniqKey="Lee M">MY Lee</name></author><author><name sortKey="Wang, Sh" uniqKey="Wang S">SH Wang</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Bidra, As" uniqKey="Bidra A">AS Bidra</name></author><author><name sortKey="Taylor, Td" uniqKey="Taylor T">TD Taylor</name></author><author><name sortKey="Agar, Jr" uniqKey="Agar J">JR Agar</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Butscher, A" uniqKey="Butscher A">A Butscher</name></author><author><name sortKey="Bohner, M" uniqKey="Bohner M">M Bohner</name></author><author><name sortKey="Doebelin, N" uniqKey="Doebelin N">N Doebelin</name></author><author><name sortKey="Hofmann, S" uniqKey="Hofmann S">S Hofmann</name></author><author><name sortKey="Mueller, R" uniqKey="Mueller R">R Mueller</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Farzadi, A" uniqKey="Farzadi A">A Farzadi</name></author><author><name sortKey="Solati Hashjin, M" uniqKey="Solati Hashjin M">M Solati-Hashjin</name></author><author><name sortKey="Asadi Eydivand, M" uniqKey="Asadi Eydivand M">M Asadi-Eydivand</name></author><author><name sortKey="Abu Osman, Na" uniqKey="Abu Osman N">NA Abu Osman</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Chen, J" uniqKey="Chen J">J Chen</name></author><author><name sortKey="Li, W" uniqKey="Li W">W Li</name></author><author><name sortKey="Swain, Mv" uniqKey="Swain M">MV Swain</name></author><author><name sortKey="Ali Darendeliler, M" uniqKey="Ali Darendeliler M">M Ali Darendeliler</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Li, W" uniqKey="Li W">W Li</name></author><author><name sortKey="Swain, Mv" uniqKey="Swain M">MV Swain</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author><author><name sortKey="Ironside, J" uniqKey="Ironside J">J Ironside</name></author><author><name sortKey="Steven, Gp" uniqKey="Steven G">GP Steven</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Li, W" uniqKey="Li W">W Li</name></author><author><name sortKey="Swain, Mv" uniqKey="Swain M">MV Swain</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author><author><name sortKey="Steven, Gp" uniqKey="Steven G">GP Steven</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Chen, J" uniqKey="Chen J">J Chen</name></author><author><name sortKey="Rungsiyakull, C" uniqKey="Rungsiyakull C">C Rungsiyakull</name></author><author><name sortKey="Li, W" uniqKey="Li W">W Li</name></author><author><name sortKey="Chen, Y" uniqKey="Chen Y">Y Chen</name></author><author><name sortKey="Swain, M" uniqKey="Swain M">M Swain</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sato, Y" uniqKey="Sato Y">Y Sato</name></author><author><name sortKey="Abe, Y" uniqKey="Abe Y">Y Abe</name></author><author><name sortKey="Okane, H" uniqKey="Okane H">H Okane</name></author><author><name sortKey="Tsuga, K" uniqKey="Tsuga K">K Tsuga</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kupczik, K" uniqKey="Kupczik K">K Kupczik</name></author><author><name sortKey="Chattah, Nlt" uniqKey="Chattah N">NLT Chattah</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Karim, L" uniqKey="Karim L">L Karim</name></author><author><name sortKey="Vashishth, D" uniqKey="Vashishth D">D Vashishth</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Zaw, K" uniqKey="Zaw K">K Zaw</name></author><author><name sortKey="Liu, Gr" uniqKey="Liu G">GR Liu</name></author><author><name sortKey="Deng, B" uniqKey="Deng B">B Deng</name></author><author><name sortKey="Tan, Kbc" uniqKey="Tan K">KBC Tan</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Carter, Dr" uniqKey="Carter D">DR Carter</name></author><author><name sortKey="Hayes, Wc" uniqKey="Hayes W">WC Hayes</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sarrafpour, B" uniqKey="Sarrafpour B">B Sarrafpour</name></author><author><name sortKey="Swain, M" uniqKey="Swain M">M Swain</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author><author><name sortKey="Zoellner, H" uniqKey="Zoellner H">H Zoellner</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kydd, Wl" uniqKey="Kydd W">WL Kydd</name></author><author><name sortKey="Daly, Ch" uniqKey="Daly C">CH Daly</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kishi, M" uniqKey="Kishi M">M Kishi</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Bergomi, M" uniqKey="Bergomi M">M Bergomi</name></author><author><name sortKey="Cugnoni, J" uniqKey="Cugnoni J">J Cugnoni</name></author><author><name sortKey="Galli, M" uniqKey="Galli M">M Galli</name></author><author><name sortKey="Botsis, J" uniqKey="Botsis J">J Botsis</name></author><author><name sortKey="Belser, Uc" uniqKey="Belser U">UC Belser</name></author><author><name sortKey="Wiskott, Hwa" uniqKey="Wiskott H">HWA Wiskott</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Itoh, H" uniqKey="Itoh H">H Itoh</name></author><author><name sortKey="Caputo, Aa" uniqKey="Caputo A">AA Caputo</name></author><author><name sortKey="Wylie, R" uniqKey="Wylie R">R Wylie</name></author><author><name sortKey="Berg, T" uniqKey="Berg T">T Berg</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Hart, Rt" uniqKey="Hart R">RT Hart</name></author><author><name sortKey="Hennebel, Vv" uniqKey="Hennebel V">VV Hennebel</name></author><author><name sortKey="Thongpreda, N" uniqKey="Thongpreda N">N Thongpreda</name></author><author><name sortKey="Vanbuskirk, Wc" uniqKey="Vanbuskirk W">WC Vanbuskirk</name></author><author><name sortKey="Anderson, Rc" uniqKey="Anderson R">RC Anderson</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Korioth, Twp" uniqKey="Korioth T">TWP Korioth</name></author><author><name sortKey="Romilly, Dp" uniqKey="Romilly D">DP Romilly</name></author><author><name sortKey="Hannam, Ag" uniqKey="Hannam A">AG Hannam</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Prinz, Jf" uniqKey="Prinz J">JF Prinz</name></author><author><name sortKey="De Wijk, Ra" uniqKey="De Wijk R">RA de Wijk</name></author><author><name sortKey="Huntjens, L" uniqKey="Huntjens L">L Huntjens</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sajewicz, E" uniqKey="Sajewicz E">E Sajewicz</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Chen, J" uniqKey="Chen J">J Chen</name></author><author><name sortKey="Suenaga, H" uniqKey="Suenaga H">H Suenaga</name></author><author><name sortKey="Hogg, M" uniqKey="Hogg M">M Hogg</name></author><author><name sortKey="Li, W" uniqKey="Li W">W Li</name></author><author><name sortKey="Swain, M" uniqKey="Swain M">M Swain</name></author><author><name sortKey="Li, Q" uniqKey="Li Q">Q Li</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Rozvany, Gin" uniqKey="Rozvany G">GIN Rozvany</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Inokoshi, M" uniqKey="Inokoshi M">M Inokoshi</name></author><author><name sortKey="Kanazawa, M" uniqKey="Kanazawa M">M Kanazawa</name></author><author><name sortKey="Minakuchi, S" uniqKey="Minakuchi S">S Minakuchi</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Mcmillian, As" uniqKey="Mcmillian A">AS McMillian</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Davenpor, Jc" uniqKey="Davenpor J">JC Davenpor</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kubo, K" uniqKey="Kubo K">K Kubo</name></author><author><name sortKey="Kawata, T" uniqKey="Kawata T">T Kawata</name></author><author><name sortKey="Suenaga, H" uniqKey="Suenaga H">H Suenaga</name></author><author><name sortKey="Yoda, N" uniqKey="Yoda N">N Yoda</name></author><author><name sortKey="Shigemitsu, R" uniqKey="Shigemitsu R">R Shigemitsu</name></author><author><name sortKey="Ogawa, T" uniqKey="Ogawa T">T Ogawa</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Ogimoto, T" uniqKey="Ogimoto T">T Ogimoto</name></author><author><name sortKey="Ogawa, T" uniqKey="Ogawa T">T Ogawa</name></author><author><name sortKey="Sumiyoshi, K" uniqKey="Sumiyoshi K">K Sumiyoshi</name></author><author><name sortKey="Matsuka, Y" uniqKey="Matsuka Y">Y Matsuka</name></author><author><name sortKey="Koyano, K" uniqKey="Koyano K">K Koyano</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="List, T" uniqKey="List T">T List</name></author><author><name sortKey="Helkimo, M" uniqKey="Helkimo M">M Helkimo</name></author><author><name sortKey="Karlsson, R" uniqKey="Karlsson R">R Karlsson</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Scapino, Rp" uniqKey="Scapino R">RP Scapino</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Wakabayashi, N" uniqKey="Wakabayashi N">N Wakabayashi</name></author><author><name sortKey="Suzuki, T" uniqKey="Suzuki T">T Suzuki</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Ogawa, T" uniqKey="Ogawa T">T Ogawa</name></author><author><name sortKey="Tanaka, M" uniqKey="Tanaka M">M Tanaka</name></author><author><name sortKey="Ogimoto, T" uniqKey="Ogimoto T">T Ogimoto</name></author><author><name sortKey="Okushi, N" uniqKey="Okushi N">N Okushi</name></author><author><name sortKey="Koyano, K" uniqKey="Koyano K">K Koyano</name></author><author><name sortKey="Takeuchi, K" uniqKey="Takeuchi K">K Takeuchi</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Tanaka, M" uniqKey="Tanaka M">M Tanaka</name></author><author><name sortKey="Ogimoto, T" uniqKey="Ogimoto T">T Ogimoto</name></author><author><name sortKey="Koyano, K" uniqKey="Koyano K">K Koyano</name></author><author><name sortKey="Ogawa, T" uniqKey="Ogawa T">T Ogawa</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Mycroft, Rh" uniqKey="Mycroft R">RH Mycroft</name></author><author><name sortKey="Mitchell, Dc" uniqKey="Mitchell D">DC Mitchell</name></author><author><name sortKey="Kay, J" uniqKey="Kay J">J Kay</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Bradley, Jc" uniqKey="Bradley J">JC Bradley</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Akazawa, H" uniqKey="Akazawa H">H Akazawa</name></author><author><name sortKey="Sakurai, K" uniqKey="Sakurai K">K Sakurai</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Ashton, H" uniqKey="Ashton H">H Ashton</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kim, Sh" uniqKey="Kim S">SH Kim</name></author><author><name sortKey="Park, Sh" uniqKey="Park S">SH Park</name></author><author><name sortKey="Jun, Jw" uniqKey="Jun J">JW Jun</name></author><author><name sortKey="Kim, Dh" uniqKey="Kim D">DH Kim</name></author><author><name sortKey="Shin, Jw" uniqKey="Shin J">JW Shin</name></author><author><name sortKey="Han, Jy" uniqKey="Han J">JY Han</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Aspenberg, P" uniqKey="Aspenberg P">P Aspenberg</name></author><author><name sortKey="Van Der Vis, H" uniqKey="Van Der Vis H">H van der Vis</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Hill, Ee" uniqKey="Hill E">EE Hill</name></author><author><name sortKey="Breeding, Lc" uniqKey="Breeding L">LC Breeding</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Jain, A" uniqKey="Jain A">A Jain</name></author><author><name sortKey="V, V" uniqKey="V V">V V</name></author><author><name sortKey="Bharathi, Rm" uniqKey="Bharathi R">RM Bharathi</name></author><author><name sortKey="Patil, V" uniqKey="Patil V">V Patil</name></author><author><name sortKey="Alur, J" uniqKey="Alur J">J Alur</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Neumann, Jk" uniqKey="Neumann J">JK Neumann</name></author><author><name sortKey="Mccarty, Ga" uniqKey="Mccarty G">GA McCarty</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Liebenberg, Wh" uniqKey="Liebenberg W">WH Liebenberg</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Maezawa, N" uniqKey="Maezawa N">N Maezawa</name></author><author><name sortKey="Shiota, M" uniqKey="Shiota M">M Shiota</name></author><author><name sortKey="Kasugai, S" uniqKey="Kasugai S">S Kasugai</name></author><author><name sortKey="Wakabayashi, N" uniqKey="Wakabayashi N">N Wakabayashi</name></author></analytic></biblStruct></listBibl></div1></back></TEI><pmc article-type="research-article"><pmc-dir>properties open_access</pmc-dir>
<front><journal-meta><journal-id journal-id-type="nlm-ta">PLoS One</journal-id><journal-id journal-id-type="iso-abbrev">PLoS ONE</journal-id><journal-id journal-id-type="publisher-id">plos</journal-id><journal-id journal-id-type="pmc">plosone</journal-id><journal-title-group><journal-title>PLoS ONE</journal-title></journal-title-group><issn pub-type="epub">1932-6203</issn><publisher><publisher-name>Public Library of Science</publisher-name><publisher-loc>San Francisco, CA USA</publisher-loc></publisher></journal-meta><article-meta><article-id pub-id-type="pmid">26161878</article-id><article-id pub-id-type="pmc">4498620</article-id><article-id pub-id-type="doi">10.1371/journal.pone.0132552</article-id><article-id pub-id-type="publisher-id">PONE-D-15-00665</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title>Shape Optimization for Additive Manufacturing of Removable Partial Dentures - A New Paradigm for Prosthetic CAD/CAM</article-title><alt-title alt-title-type="running-head">Denture Base Optimization and CAD/CAM Fabrication</alt-title></title-group><contrib-group><contrib contrib-type="author" equal-contrib="yes"><name><surname>Chen</surname><given-names>Junning</given-names></name><xref ref-type="aff" rid="aff001"><sup>1</sup></xref></contrib><contrib contrib-type="author" equal-contrib="yes"><name><surname>Ahmad</surname><given-names>Rohana</given-names></name><xref ref-type="aff" rid="aff002"><sup>2</sup></xref></contrib><contrib contrib-type="author" equal-contrib="yes"><name><surname>Suenaga</surname><given-names>Hanako</given-names></name><xref ref-type="aff" rid="aff003"><sup>3</sup></xref></contrib><contrib contrib-type="author" equal-contrib="yes"><name><surname>Li</surname><given-names>Wei</given-names></name><xref ref-type="aff" rid="aff001"><sup>1</sup></xref></contrib><contrib contrib-type="author" equal-contrib="yes"><name><surname>Sasaki</surname><given-names>Keiichi</given-names></name><xref ref-type="aff" rid="aff004"><sup>4</sup></xref></contrib><contrib contrib-type="author" equal-contrib="yes"><name><surname>Swain</surname><given-names>Michael</given-names></name><xref ref-type="aff" rid="aff005"><sup>5</sup></xref></contrib><contrib contrib-type="author" equal-contrib="yes"><name><surname>Li</surname><given-names>Qing</given-names></name><xref ref-type="aff" rid="aff001"><sup>1</sup></xref><xref rid="cor001" ref-type="corresp">*</xref></contrib></contrib-group><aff id="aff001"><label>1</label><addr-line>School of Aerospace, Mechanical and Mechatronic Engineering, the University of Sydney, Sydney, NSW 2006, Australia</addr-line></aff><aff id="aff002"><label>2</label><addr-line>Unit of Prosthodontics, Faculty of Dentistry, Shah Alam & Integrative Pharmacogenomics Institute (iPROMISE), Universiti Teknologi MARA, Bandar Puncak Alam, Selangor, 42300, Malaysia</addr-line></aff><aff id="aff003"><label>3</label><addr-line>Division of Preventive Dentistry, Tohoku University Graduate School of Dentistry, 4–1 Seiryo-machi, Aoba-ku, Sendai, 980–8575, Japan</addr-line></aff><aff id="aff004"><label>4</label><addr-line>Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, 4–1 Seiryo-machi, Aoba-ku, Sendai, 980–8575, Japan</addr-line></aff><aff id="aff005"><label>5</label><addr-line>Faculty of Dentistry, The University of Sydney, Sydney, NSW 2006, Australia</addr-line></aff><contrib-group><contrib contrib-type="editor"><name><surname>Matsumoto</surname><given-names>Takuya</given-names></name><role>Editor</role><xref ref-type="aff" rid="edit1"></xref></contrib></contrib-group><aff id="edit1"><addr-line>Department of Biomaterials, JAPAN</addr-line></aff><author-notes><fn fn-type="conflict" id="coi001"><p><bold>Competing Interests: </bold>The authors have declared that no competing interests exist.</p></fn><fn fn-type="con" id="contrib001"><p>Conceived and designed the experiments: JC RA HS WL MS QL KS. Performed the experiments: JC HS WL. Analyzed the data: JC RA HS WL. Contributed reagents/materials/analysis tools: JC RA HS WL MS QL KS. Wrote the paper: JC RA HS WL MS QL KS.</p></fn><corresp id="cor001">* E-mail: <email>qing.li@sydney.edu.au</email></corresp></author-notes><pub-date pub-type="epub"><day>10</day><month>7</month><year>2015</year></pub-date><pub-date pub-type="collection"><year>2015</year></pub-date><volume>10</volume><issue>7</issue><elocation-id>e0132552</elocation-id><history><date date-type="received"><day>19</day><month>1</month><year>2015</year></date><date date-type="accepted"><day>17</day><month>6</month><year>2015</year></date></history><permissions><copyright-year>2015</copyright-year><copyright-holder>Chen et al</copyright-holder><license xlink:href="http://creativecommons.org/licenses/by/4.0/"><license-p>This is an open access article distributed under the terms of the <ext-link ext-link-type="uri" xlink:href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution License</ext-link>, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited</license-p></license></permissions><self-uri content-type="pdf" xlink:type="simple" xlink:href="pone.0132552.pdf"></self-uri><abstract><p>With ever-growing aging population and demand for denture treatments, pressure-induced mucosa lesion and residual ridge resorption remain main sources of clinical complications. Conventional denture design and fabrication are challenged for its labor and experience intensity, urgently necessitating an automatic procedure. This study aims to develop a fully automatic procedure enabling shape optimization and additive manufacturing of removable partial dentures (RPD), to maximize the uniformity of contact pressure distribution on the mucosa, thereby reducing associated clinical complications. A 3D heterogeneous finite element (FE) model was constructed from CT scan, and the critical tissue of mucosa was modeled as a hyperelastic material from <italic>in vivo</italic> clinical data. A contact shape optimization algorithm was developed based on the bi-directional evolutionary structural optimization (BESO) technique. Both initial and optimized dentures were prototyped by 3D printing technology and evaluated with <italic>in vitro</italic> tests. Through the optimization, the peak contact pressure was reduced by 70%, and the uniformity was improved by 63%. <italic>In vitro</italic> tests verified the effectiveness of this procedure, and the hydrostatic pressure induced in the mucosa is well below clinical pressure-pain thresholds (PPT), potentially lessening risk of residual ridge resorption. This proposed computational optimization and additive fabrication procedure provides a novel method for fast denture design and adjustment at low cost, with quantitative guidelines and computer aided design and manufacturing (CAD/CAM) for a specific patient. The integration of digitalized modeling, computational optimization, and free-form fabrication enables more efficient clinical adaptation. The customized optimal denture design is expected to minimize pain/discomfort and potentially reduce long-term residual ridge resorption.</p></abstract><funding-group><funding-statement>This work was supported by the Australian Research Council Discovery Scheme, grant number DP1095140 (<ext-link ext-link-type="uri" xlink:href="http://www.arc.gov.au/ncgp/dp/dp_default.htm">http://www.arc.gov.au/ncgp/dp/dp_default.htm</ext-link>), and the Australian Research Council Fellowship Scheme, grant number FT120100947 (<ext-link ext-link-type="uri" xlink:href="http://www.arc.gov.au/ncgp/futurefel/future_default.htm">http://www.arc.gov.au/ncgp/futurefel/future_default.htm</ext-link>).</funding-statement></funding-group><counts><fig-count count="6"></fig-count><table-count count="1"></table-count><page-count count="17"></page-count></counts><custom-meta-group><custom-meta id="data-availability"><meta-name>Data Availability</meta-name><meta-value>All data are available as Supporting Information.</meta-value></custom-meta></custom-meta-group></article-meta><notes><title>Data Availability</title><p>All data are available as Supporting Information.</p></notes></front><body><sec sec-type="intro" id="sec001"><title>Introduction</title><p>Denture treatments have been widely applied in dental practice to restore oral function of the edentulous group [<xref rid="pone.0132552.ref001" ref-type="bibr">1</xref>]. In all cases of tissue-borne, tooth-tissue-borne, and implant-retained dentures, the oral mucosa plays a critical role in distributing occlusal loads from the denture to the underlying bony ridge during mastication [<xref rid="pone.0132552.ref002" ref-type="bibr">2</xref>–<xref rid="pone.0132552.ref005" ref-type="bibr">5</xref>]. The contact pressure developed over this highly vascular tissue indicates one of the most important etiological factors causing the clinical complications [<xref rid="pone.0132552.ref005" ref-type="bibr">5</xref>–<xref rid="pone.0132552.ref008" ref-type="bibr">8</xref>] and highly correlated with prognosis [<xref rid="pone.0132552.ref009" ref-type="bibr">9</xref>]. Excessive contact pressure under the denture disturbs local blood supply to the underlying bone, triggering nerve pain and discomfort in patients [<xref rid="pone.0132552.ref009" ref-type="bibr">9</xref>–<xref rid="pone.0132552.ref011" ref-type="bibr">11</xref>], thus compromising their quality of life [<xref rid="pone.0132552.ref012" ref-type="bibr">12</xref>]. In more severe cases, subsequent residual ridge bone resorption may develop [<xref rid="pone.0132552.ref013" ref-type="bibr">13</xref>, <xref rid="pone.0132552.ref014" ref-type="bibr">14</xref>].</p><p>Contact pressure distribution can be affected by the anatomy and physiological responses of both residual mucosa and underlying jaw bone [<xref rid="pone.0132552.ref002" ref-type="bibr">2</xref>–<xref rid="pone.0132552.ref004" ref-type="bibr">4</xref>, <xref rid="pone.0132552.ref006" ref-type="bibr">6</xref>, <xref rid="pone.0132552.ref007" ref-type="bibr">7</xref>, <xref rid="pone.0132552.ref015" ref-type="bibr">15</xref>], leading to distinctive patterns in the individual patients. Conventional denture fabrication using final cast models [<xref rid="pone.0132552.ref016" ref-type="bibr">16</xref>–<xref rid="pone.0132552.ref019" ref-type="bibr">19</xref>] is unable to take into account either the nonlinear soft tissue responses or the heterogeneous jaw bone with local variations, and the fabricated denture base reflects only surface morphology of residual ridge. Meanwhile, this labor-intensive process may result in variable adaptive accuracies with different fabrication techniques and experience levels [<xref rid="pone.0132552.ref016" ref-type="bibr">16</xref>].</p><p>The finite element (FE) method has demonstrated its compelling advantages for biomechanical analysis and surgical planning [<xref rid="pone.0132552.ref020" ref-type="bibr">20</xref>–<xref rid="pone.0132552.ref022" ref-type="bibr">22</xref>]. When combined with clinical computed tomography (CT), precise 3D morphologies can be modeled properly with both anatomical and physiological features of an individual patient [<xref rid="pone.0132552.ref001" ref-type="bibr">1</xref>]. Increasing computational power enables to more realistically modelling tissue behavior, including complex nonlinear biomaterial responses [<xref rid="pone.0132552.ref020" ref-type="bibr">20</xref>]. Furthermore, computational design allows optimizing the shape of an engineering structure, and has been applied for addressing design issues involving sophisticated contact conditions [<xref rid="pone.0132552.ref023" ref-type="bibr">23</xref>–<xref rid="pone.0132552.ref026" ref-type="bibr">26</xref>]. Following the success achieved in engineering, the denture base can potentially be modified and adjusted pre-fabrication and pre-clinical try-in to avoid possible excessive contact pressure over the underlying mucosa to minimize potential clinical complications [<xref rid="pone.0132552.ref027" ref-type="bibr">27</xref>]. This computational approach also facilitates various digitalized additive manufacturing, forming a CAD/CAM procedure for ensuring controllable consistency and standardized accuracy [<xref rid="pone.0132552.ref028" ref-type="bibr">28</xref>–<xref rid="pone.0132552.ref030" ref-type="bibr">30</xref>].</p><p>This study aims to develop a fully automatic computational algorithm for denture base design in a patient-specific removable partial denture (RPD) by increasing the uniformity of contact pressure, followed by additive prototyping and <italic>in vitro</italic> verification. A 3D heterogeneous FE model of the patient’s mandible with teeth and RPD is first created based on clinical CT data, with the mucosa modeled as a nonlinear (hyperelastic) material in response to mastication. Both initial and optimized dentures were prototyped by 3D printing technology, which were subsequently tested with pressure sensitive silicone and films, to verify the effectiveness of the proposed procedure <italic>in vitro</italic>. Both pressure-induced pain and hydrostatic pressure in the mucosa are examined with the initial and optimal contact surfaces against clinical data reported in literature. From biomedical perspective, this study develops a novel procedure by the integration of FE based automatic design optimization and additive fabrication (3D printing). From a clinical perspective, this novel technique automates patient-specific denture fitting with quantitative guidelines for denture adjustment and correction in a more efficient way. From a patient perspective, the optimized denture would potentially minimize pain/discomfort and reduce long-term residual ridge resorption, thereby maximizing intervals between further adjustments of denture.</p></sec><sec sec-type="materials|methods" id="sec002"><title>Materials and Methods</title><sec id="sec003"><title>Patient data acquisition and modeling</title><p>The research protocols and a patient consent form were approved by the research ethics committee at both the Tohoku University Graduate School of Dentistry and Sendai Kousei Hospital. For this study, a written patient consent form was provided and signed by the participant for utilizing the image data. The specific subject was a female at early 60s, and her left mandible with partially edentulous area was reconstructed up to the midsagittal plane from the clinical CT scans with a resolution of 0.3 mm per pixel, for the region of interest and computational efficiency, in ScanIP Ver. 4.3 (Simpleware Ltd, Exeter UK) [<xref rid="pone.0132552.ref031" ref-type="bibr">31</xref>]. The geometric models were then created by using non-uniform rational B-splines (NURBS) in the 3D parametric modeling software Rhinoceros 3.0 (Robert McNeel & Associates, Seattle USA) (<xref rid="pone.0132552.g001" ref-type="fig">Fig 1a</xref>). The experimental RPD was made with a titanium frame, a scanning resin denture base, and radiopaque artificial teeth, for the scanning purpose, and modeled for virtual insertion through the surface contour registration between the rest seats on the abutment teeth and the rest of RPD components in Rhinoceros (<xref rid="pone.0132552.g001" ref-type="fig">Fig 1b</xref>). This initial model provides a baseline for the base contact without mastication prior to optimization.</p><fig id="pone.0132552.g001" orientation="portrait" position="float"><object-id pub-id-type="doi">10.1371/journal.pone.0132552.g001</object-id><label>Fig 1</label><caption><p>The model was created based on patient-specific clinical data, a) two sets of CBCT data were reconstructed to form masks (Set 1: white—teeth, orange—bone, transparent pink—mucosa, grey—teeth; Set 2: grey—artificial teeth, transparent cyan—denture base, blue—denture frame); b) both models are solidified by using NURBS and assembled; c) assignment of heterogeneous material property of the bone based on HU value; d) the nodes highlighted in red on the denture base are allowed to be modified during bi-directional evolutionary shape optimization (BESO), and the orange ones are fixed to maintain the denture functionality.</p></caption><graphic xlink:href="pone.0132552.g001"></graphic></fig><p>The FE model was meshed in ABAQUS 6.9.2 (Dassault Systèmes, Waltham USA), with a mesh convergence test to ensure sufficient numerical accuracy [<xref rid="pone.0132552.ref032" ref-type="bibr">32</xref>, <xref rid="pone.0132552.ref033" ref-type="bibr">33</xref>]. The final mesh contains 186 213 degrees of freedom (D.O.F.) with 328 066 tetrahedral elements in the hybrid formulation (C3D4H) to preserve the smoothness of the contact surfaces in the nonlinear analysis.</p></sec><sec id="sec004"><title>Material assignment and loading scenario</title><p>The common assumptions of linear elastic and homogenous materials [<xref rid="pone.0132552.ref034" ref-type="bibr">34</xref>, <xref rid="pone.0132552.ref035" ref-type="bibr">35</xref>] may not adequately replicate complex tissue responses [<xref rid="pone.0132552.ref020" ref-type="bibr">20</xref>]. In this study the mandibular bone was more realistically characterized as a heterogeneous material based on the HU values [<xref rid="pone.0132552.ref036" ref-type="bibr">36</xref>], reflecting the variation of localized modulus and load deflection [<xref rid="pone.0132552.ref034" ref-type="bibr">34</xref>, <xref rid="pone.0132552.ref037" ref-type="bibr">37</xref>], as well as soft tissue response on the surface [<xref rid="pone.0132552.ref020" ref-type="bibr">20</xref>]. The apparent bone density <italic>ρ</italic><sub><italic>app</italic></sub> is interpolated linearly against the HU value as in <xref rid="pone.0132552.e002" ref-type="disp-formula">Eq (1)</xref>, with the thresholds of 1.86 g/cm<sup>3</sup> and 0.72 g/cm<sup>3</sup> for cortical and cancellous bones [<xref rid="pone.0132552.ref038" ref-type="bibr">38</xref>] (the resultant bone density contour in <xref rid="pone.0132552.g001" ref-type="fig">Fig 1c</xref>). <xref rid="pone.0132552.e003" ref-type="disp-formula">Eq (2)</xref> was adopted here to correlate the Young’s modulus <italic>E</italic> to the apparent density <italic>ρ</italic><sub><italic>app</italic></sub> [<xref rid="pone.0132552.ref039" ref-type="bibr">39</xref>], and a User Defined Field (USDFLD) subroutine was employed to assign heterogeneous material properties in ABAQUS, where the rate-dependent term, <inline-formula id="pone.0132552.e001"><alternatives><graphic xlink:href="pone.0132552.e001.jpg" id="pone.0132552.e001g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M1"><mml:msubsup><mml:mrow><mml:mover accent="true"><mml:mrow><mml:mi>ε</mml:mi></mml:mrow><mml:mo>˙</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mn>0.06</mml:mn></mml:mrow></mml:msubsup></mml:math></alternatives></inline-formula>, was assumed to be approaching 1 as the low speed loading in the normal chewing activities. For the simplification of the simulation, the isotropy of the mandibular bone is assumed [<xref rid="pone.0132552.ref034" ref-type="bibr">34</xref>, <xref rid="pone.0132552.ref036" ref-type="bibr">36</xref>, <xref rid="pone.0132552.ref037" ref-type="bibr">37</xref>, <xref rid="pone.0132552.ref040" ref-type="bibr">40</xref>], as its directional difference is much less significant compared to its heterogeneity and the soft tissue mucosa.</p><disp-formula id="pone.0132552.e002"><alternatives><graphic xlink:href="pone.0132552.e002.jpg" id="pone.0132552.e002g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M2"><mml:mrow><mml:msub><mml:mi>ρ</mml:mi><mml:mrow><mml:mi>a</mml:mi><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:msub><mml:mi>ρ</mml:mi><mml:mrow><mml:mtext>min</mml:mtext></mml:mrow></mml:msub><mml:mo>+</mml:mo><mml:mo stretchy="false">(</mml:mo><mml:msub><mml:mi>ρ</mml:mi><mml:mrow><mml:mtext>max</mml:mtext></mml:mrow></mml:msub><mml:mo>−</mml:mo><mml:msub><mml:mi>ρ</mml:mi><mml:mrow><mml:mtext>min</mml:mtext></mml:mrow></mml:msub><mml:mo stretchy="false">)</mml:mo><mml:mo>×</mml:mo><mml:mfrac><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>H</mml:mi><mml:mi>U</mml:mi><mml:mo>−</mml:mo><mml:mi>H</mml:mi><mml:msub><mml:mi>U</mml:mi><mml:mrow><mml:mtext>min</mml:mtext></mml:mrow></mml:msub><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>H</mml:mi><mml:msub><mml:mi>U</mml:mi><mml:mrow><mml:mtext>max</mml:mtext></mml:mrow></mml:msub><mml:mo>−</mml:mo><mml:mi>H</mml:mi><mml:msub><mml:mi>U</mml:mi><mml:mrow><mml:mtext>min</mml:mtext></mml:mrow></mml:msub><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mfrac></mml:mrow></mml:math></alternatives><label>(1)</label></disp-formula><disp-formula id="pone.0132552.e003"><alternatives><graphic xlink:href="pone.0132552.e003.jpg" id="pone.0132552.e003g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M3"><mml:mrow><mml:mi>E</mml:mi><mml:mo>=</mml:mo><mml:mn>3790</mml:mn><mml:msubsup><mml:mover accent="true"><mml:mi>ε</mml:mi><mml:mo>˙</mml:mo></mml:mover><mml:mi>e</mml:mi><mml:mrow><mml:mn>0.06</mml:mn></mml:mrow></mml:msubsup><mml:msubsup><mml:mi>ρ</mml:mi><mml:mrow><mml:mi>a</mml:mi><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msubsup></mml:mrow></mml:math></alternatives><label>(2)</label></disp-formula><disp-formula id="pone.0132552.e004"><alternatives><graphic xlink:href="pone.0132552.e004.jpg" id="pone.0132552.e004g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M4"><mml:mrow><mml:msub><mml:mi>U</mml:mi><mml:mi>ε</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:munderover><mml:mstyle mathsize="140%" displaystyle="true"><mml:mo>∑</mml:mo></mml:mstyle><mml:mrow><mml:mi>i</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn></mml:mrow><mml:mi>M</mml:mi></mml:munderover><mml:mfrac><mml:mrow><mml:mn>2</mml:mn><mml:msub><mml:mi>μ</mml:mi><mml:mi>i</mml:mi></mml:msub></mml:mrow><mml:mrow><mml:msubsup><mml:mi>α</mml:mi><mml:mi>i</mml:mi><mml:mn>2</mml:mn></mml:msubsup></mml:mrow></mml:mfrac><mml:mo stretchy="false">(</mml:mo><mml:msubsup><mml:mover accent="true"><mml:mi>λ</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mn>1</mml:mn><mml:mrow><mml:msub><mml:mi>α</mml:mi><mml:mi>i</mml:mi></mml:msub></mml:mrow></mml:msubsup><mml:mo>+</mml:mo><mml:msubsup><mml:mover accent="true"><mml:mi>λ</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mn>2</mml:mn><mml:mrow><mml:msub><mml:mi>α</mml:mi><mml:mi>i</mml:mi></mml:msub></mml:mrow></mml:msubsup><mml:mo>+</mml:mo><mml:msubsup><mml:mover accent="true"><mml:mi>λ</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mn>3</mml:mn><mml:mrow><mml:msub><mml:mi>α</mml:mi><mml:mi>i</mml:mi></mml:msub></mml:mrow></mml:msubsup><mml:mo>−</mml:mo><mml:mn>3</mml:mn><mml:mo stretchy="false">)</mml:mo><mml:mo>+</mml:mo><mml:munderover><mml:mstyle mathsize="140%" displaystyle="true"><mml:mo>∑</mml:mo></mml:mstyle><mml:mrow><mml:mi>i</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn></mml:mrow><mml:mi>N</mml:mi></mml:munderover><mml:mfrac><mml:mn>1</mml:mn><mml:mrow><mml:msub><mml:mi>D</mml:mi><mml:mi>i</mml:mi></mml:msub></mml:mrow></mml:mfrac><mml:msup><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:msup><mml:mi>J</mml:mi><mml:mrow><mml:mi>ε</mml:mi><mml:mi>l</mml:mi></mml:mrow></mml:msup><mml:mo>−</mml:mo><mml:mn>1</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mi>i</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math></alternatives><label>(3)</label></disp-formula><p>A hyperelastic constitutive material model was adopted for the mucosa to better represent its nonlinear response under mechanical loading [<xref rid="pone.0132552.ref003" ref-type="bibr">3</xref>, <xref rid="pone.0132552.ref041" ref-type="bibr">41</xref>, <xref rid="pone.0132552.ref042" ref-type="bibr">42</xref>]. This material model depends upon the strain energy (<italic>U</italic><sub><italic>ε</italic></sub>) stored per unit volume as a function of the instantaneous volume strain (<italic>J</italic><sup><italic>εl</italic></sup>) at a point of the material, and was derived from the clinical data [<xref rid="pone.0132552.ref042" ref-type="bibr">42</xref>] via the least-squares fitting. The third order Ogden strain energy constitutive model equation [<xref rid="pone.0132552.ref043" ref-type="bibr">43</xref>] was determined to provide the closest match (<xref rid="pone.0132552.e004" ref-type="disp-formula">Eq 3</xref>) with the least complexity, where <inline-formula id="pone.0132552.e005"><alternatives><graphic xlink:href="pone.0132552.e005.jpg" id="pone.0132552.e005g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M5"><mml:msub><mml:mrow><mml:mover accent="true"><mml:mrow><mml:mi>λ</mml:mi></mml:mrow><mml:mo>-</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mi>i</mml:mi></mml:mrow></mml:msub></mml:math></alternatives></inline-formula> are the deviatoric principal stretches obtained from the principal stretches, <italic>M</italic> (= 3 in this case) is the order of this fitting equation. <xref rid="pone.0132552.t001" ref-type="table">Table 1</xref> summarizes all the material properties, including <italic>μ</italic><sub><italic>i</italic></sub>, <italic>α</italic><sub><italic>i</italic></sub>, and <italic>D</italic><sub><italic>i</italic></sub> for the hyperelastic model [<xref rid="pone.0132552.ref001" ref-type="bibr">1</xref>, <xref rid="pone.0132552.ref034" ref-type="bibr">34</xref>, <xref rid="pone.0132552.ref035" ref-type="bibr">35</xref>].</p><table-wrap id="pone.0132552.t001" orientation="portrait" position="float"><object-id pub-id-type="doi">10.1371/journal.pone.0132552.t001</object-id><label>Table 1</label><caption><title>Material properties of the denture and mandible.</title></caption><alternatives><graphic id="pone.0132552.t001g" xlink:href="pone.0132552.t001"></graphic><table frame="hsides" rules="groups"><colgroup span="1"><col align="left" valign="middle" span="1"></col><col align="left" valign="middle" span="1"></col><col align="left" valign="middle" span="1"></col><col align="left" valign="middle" span="1"></col><col align="left" valign="middle" span="1"></col></colgroup><thead><tr><th align="left" rowspan="1" colspan="1">Material</th><th colspan="2" align="center" rowspan="1">Young Modulus (MPa)</th><th colspan="2" align="center" rowspan="1">Poisson Ratio</th></tr></thead><tbody><tr><td align="left" rowspan="1" colspan="1"><bold>Bone</bold></td><td colspan="2" align="center" rowspan="1">Heterogeneous</td><td colspan="2" align="center" rowspan="1">0.30</td></tr><tr><td align="left" rowspan="1" colspan="1"><bold>Denture Frame (Titanium)</bold></td><td colspan="2" align="center" rowspan="1">110 000</td><td colspan="2" align="center" rowspan="1">0.35</td></tr><tr><td align="left" rowspan="1" colspan="1"><bold>Denture Base (Acrylic)</bold></td><td colspan="2" align="center" rowspan="1">2 650</td><td colspan="2" align="center" rowspan="1">0.30</td></tr><tr><td align="left" rowspan="1" colspan="1"><bold>Artificial Tooth (Porcelain)</bold></td><td colspan="2" align="center" rowspan="1">140 000</td><td colspan="2" align="center" rowspan="1">0.28</td></tr><tr><td align="left" rowspan="1" colspan="1"><bold>Tooth</bold></td><td colspan="2" align="center" rowspan="1">84 100</td><td colspan="2" align="center" rowspan="1">0.20</td></tr><tr><td align="left" rowspan="1" colspan="1"><bold>Mucosa</bold></td><td colspan="2" align="center" rowspan="1"><bold>Hyperelastic</bold></td><td colspan="2" align="center" rowspan="1">0.47</td></tr><tr><td rowspan="4" align="left" colspan="1"><bold><italic>(Ogden 3<sup>rd</sup>)</italic></bold></td><td align="left" rowspan="1" colspan="1"><italic>i</italic></td><td align="left" rowspan="1" colspan="1"><italic>μ<sub>i</sub></italic></td><td align="left" rowspan="1" colspan="1"><italic>α<sub>i</sub></italic></td><td align="left" rowspan="1" colspan="1"><italic>D<sub>i</sub></italic></td></tr><tr><td align="left" rowspan="1" colspan="1">1</td><td align="left" rowspan="1" colspan="1">3.26E-02</td><td align="left" rowspan="1" colspan="1">8.41</td><td align="left" rowspan="1" colspan="1">12.47</td></tr><tr><td align="left" rowspan="1" colspan="1">2</td><td align="left" rowspan="1" colspan="1">7.88E-04</td><td align="left" rowspan="1" colspan="1">25.00</td><td align="left" rowspan="1" colspan="1">0</td></tr><tr><td align="left" rowspan="1" colspan="1">3</td><td align="left" rowspan="1" colspan="1">1.03E-03</td><td align="left" rowspan="1" colspan="1">-18.94</td><td align="left" rowspan="1" colspan="1">0</td></tr></tbody></table></alternatives></table-wrap><p>In this study, the unilateral biting is considered as the critical activity in mastication. To simulate this loading scenario, a localized masticatory force was applied in the vicinity of the first molar approximately along the tooth axis with a magnitude of 130 N [<xref rid="pone.0132552.ref040" ref-type="bibr">40</xref>, <xref rid="pone.0132552.ref044" ref-type="bibr">44</xref>]. Different masticatory activities (e.g. grinding) with various loading patterns may affect the optimization outcome, but their effects are less significant compared to the direct biting because of the magnitudes [<xref rid="pone.0132552.ref023" ref-type="bibr">23</xref>]. The boundary conditions were prescribed to the distal condyle with full kinematic constraints and the sagittal plane with symmetric constraints [<xref rid="pone.0132552.ref045" ref-type="bibr">45</xref>, <xref rid="pone.0132552.ref046" ref-type="bibr">46</xref>]. A perfect clasp fitting was assumed for this simulation to reduce computational load with a focus on the mucosa-denture interface. The Augmented Lagrangian algorithm was adopted to simulate the denture-mucosa contact, with a low frictional coefficient assumed at 0.1 to mimic typical lubrication in the oral environment [<xref rid="pone.0132552.ref047" ref-type="bibr">47</xref>, <xref rid="pone.0132552.ref048" ref-type="bibr">48</xref>, <xref rid="pone.0132552.ref049" ref-type="bibr">49</xref>].</p></sec><sec id="sec005"><title>Bi-directional evolutionary structural optimization (BESO)</title><p>The BESO algorithm is a heuristic and non-gradient approach [<xref rid="pone.0132552.ref023" ref-type="bibr">23</xref>] making adjustment to a structure by progressively adding material to where it is most needed, and removing material from where it is most redundant in a concurrent manner. Conventional element-based BESO [<xref rid="pone.0132552.ref023" ref-type="bibr">23</xref>, <xref rid="pone.0132552.ref050" ref-type="bibr">50</xref>] leads to non-smooth zigzag boundaries, and hence it is modified significantly here by using a cloud of surface nodes, rather than individual elements, as the design domain. This preserves a functional shape for a realistic contact. The surface mesh in <xref rid="pone.0132552.g001" ref-type="fig">Fig 1d</xref> indicates the boundary nodes in the design domain, where two groups of such nodes are highlighted in red (i.e. free-to-move nodes and capable of being optimized) and orange (constrained to maintain the functionality of a denture).</p><p>The clinical expectation is to avoid undesirable contact stress concentrations over the entire contact profile (denoted as <italic>g</italic>(<italic>x</italic>,<italic>y</italic>,<italic>z</italic>) in <xref rid="pone.0132552.e008" ref-type="disp-formula">Eq (4)</xref>). This can be achieved by reducing the overall deviation (<italic>F</italic> in <xref rid="pone.0132552.e008" ref-type="disp-formula">Eq (4)</xref>) of the contact pressure, which reduces the magnitude of the upper extremes and improves the effectiveness of the lower extremes. <italic>N</italic> denotes the total number of nodes in the design domain; <italic>σ</italic><sub><italic>i</italic></sub> is the nodal contact pressure, and <inline-formula id="pone.0132552.e006"><alternatives><graphic xlink:href="pone.0132552.e006.jpg" id="pone.0132552.e006g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M6"><mml:mover accent="true"><mml:mrow><mml:mi>σ</mml:mi></mml:mrow><mml:mo>-</mml:mo></mml:mover></mml:math></alternatives></inline-formula> is the average contact pressure in each iteration (<italic>k =</italic> 1,2,<italic>…K</italic>). The optimization criterion is considered convergent when the average change of objective function over 5 contiguous iterations is less than 1% (Eq (<xref rid="pone.0132552.e009" ref-type="disp-formula">5</xref>)). The interfacial contact surface <italic>g</italic> is modified by implementing nodal movement <bold><italic>δ</italic></bold> as <xref rid="pone.0132552.e010" ref-type="disp-formula">Eq (6)</xref>, and an adaptive modification rate (<inline-formula id="pone.0132552.e007"><alternatives><graphic xlink:href="pone.0132552.e007.jpg" id="pone.0132552.e007g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M7"><mml:mrow><mml:mi>M</mml:mi><mml:msubsup><mml:mi>R</mml:mi><mml:mrow><mml:mi>A</mml:mi><mml:mi>d</mml:mi><mml:mi>a</mml:mi><mml:mi>p</mml:mi><mml:mi>t</mml:mi><mml:mi>i</mml:mi><mml:mi>v</mml:mi><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>k</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula>) controlled by the maximum contact pressure ratio as defined in <xref rid="pone.0132552.e011" ref-type="disp-formula">Eq (7)</xref>, where the initial modification rate is set to <italic>MR</italic><sup>(0)</sup> = 1% herein and the subsequent modification rate is defined by the ratio between the iterative maximum and the initial maximum contact pressures. The whole contact-based BESO procedure is depicted in the flowchart shown in <xref rid="pone.0132552.g002" ref-type="fig">Fig 2</xref>.</p><fig id="pone.0132552.g002" orientation="portrait" position="float"><object-id pub-id-type="doi">10.1371/journal.pone.0132552.g002</object-id><label>Fig 2</label><caption><title>The flow chart illustrates the contact-based BESO procedure for optimization of denture contact surface.</title></caption><graphic xlink:href="pone.0132552.g002"></graphic></fig><disp-formula id="pone.0132552.e008"><alternatives><graphic xlink:href="pone.0132552.e008.jpg" id="pone.0132552.e008g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M8"><mml:mrow><mml:mtext>min</mml:mtext><mml:mi>F</mml:mi><mml:mo>=</mml:mo><mml:mtext> </mml:mtext><mml:msup><mml:mi>f</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>k</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msup><mml:mrow><mml:mo>[</mml:mo><mml:mrow><mml:mi>g</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>x</mml:mi><mml:mo>,</mml:mo><mml:mi>y</mml:mi><mml:mo>,</mml:mo><mml:mi>z</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>]</mml:mo></mml:mrow><mml:mo>=</mml:mo><mml:msqrt><mml:mrow><mml:mfrac><mml:mn>1</mml:mn><mml:mi>N</mml:mi></mml:mfrac><mml:mstyle displaystyle="true"><mml:munderover><mml:mo>∑</mml:mo><mml:mrow><mml:mi>i</mml:mi><mml:mo>=</mml:mo><mml:mn>0</mml:mn></mml:mrow><mml:mi>N</mml:mi></mml:munderover><mml:mrow><mml:msup><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:msub><mml:mi>σ</mml:mi><mml:mi>i</mml:mi></mml:msub><mml:mo>−</mml:mo><mml:msup><mml:mover accent="true"><mml:mi>σ</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>k</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msup><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:mstyle></mml:mrow></mml:msqrt></mml:mrow></mml:math></alternatives><label>(4)</label></disp-formula><disp-formula id="pone.0132552.e009"><alternatives><graphic xlink:href="pone.0132552.e009.jpg" id="pone.0132552.e009g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M9"><mml:mrow><mml:mtext> </mml:mtext><mml:mi>τ</mml:mi><mml:mo>=</mml:mo><mml:mfrac><mml:mrow><mml:munderover><mml:mrow><mml:mtext>max</mml:mtext></mml:mrow><mml:mrow><mml:mi>k</mml:mi><mml:mo>=</mml:mo><mml:mi>K</mml:mi><mml:mo>−</mml:mo><mml:mn>4</mml:mn></mml:mrow><mml:mi>K</mml:mi></mml:munderover><mml:msup><mml:mi>f</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>k</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msup><mml:mrow><mml:mo>[</mml:mo><mml:mrow><mml:mi>g</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>x</mml:mi><mml:mo>,</mml:mo><mml:mi>y</mml:mi><mml:mo>,</mml:mo><mml:mi>z</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>]</mml:mo></mml:mrow><mml:mo>−</mml:mo><mml:munderover><mml:mrow><mml:mtext>min</mml:mtext></mml:mrow><mml:mrow><mml:mi>k</mml:mi><mml:mo>=</mml:mo><mml:mi>K</mml:mi><mml:mo>−</mml:mo><mml:mn>4</mml:mn></mml:mrow><mml:mi>K</mml:mi></mml:munderover><mml:msup><mml:mi>f</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>k</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msup><mml:mrow><mml:mo>[</mml:mo><mml:mrow><mml:mi>g</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>x</mml:mi><mml:mo>,</mml:mo><mml:mi>y</mml:mi><mml:mo>,</mml:mo><mml:mi>z</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>]</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mfrac><mml:mn>1</mml:mn><mml:mn>5</mml:mn></mml:mfrac><mml:mstyle displaystyle="true"><mml:munderover><mml:mo>∑</mml:mo><mml:mrow><mml:mi>k</mml:mi><mml:mo>=</mml:mo><mml:mi>K</mml:mi><mml:mo>−</mml:mo><mml:mn>4</mml:mn></mml:mrow><mml:mi>K</mml:mi></mml:munderover><mml:mrow><mml:msup><mml:mi>f</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>k</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msup><mml:mrow><mml:mo>[</mml:mo><mml:mrow><mml:mi>g</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>x</mml:mi><mml:mo>,</mml:mo><mml:mi>y</mml:mi><mml:mo>,</mml:mo><mml:mi>z</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>]</mml:mo></mml:mrow></mml:mrow></mml:mstyle></mml:mrow></mml:mfrac><mml:mo>≤</mml:mo><mml:mn>1</mml:mn><mml:mi>%</mml:mi></mml:mrow></mml:math></alternatives><label>(5)</label></disp-formula><disp-formula id="pone.0132552.e010"><alternatives><graphic xlink:href="pone.0132552.e010.jpg" id="pone.0132552.e010g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M10"><mml:mrow><mml:msub><mml:mstyle mathvariant="bold-italic" mathsize="normal"><mml:mi>δ</mml:mi></mml:mstyle><mml:mi>i</mml:mi></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mi>x</mml:mi><mml:mo>,</mml:mo><mml:mi>y</mml:mi><mml:mo>,</mml:mo><mml:mi>z</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mo>=</mml:mo><mml:mo>−</mml:mo><mml:mi>M</mml:mi><mml:mi>R</mml:mi><mml:mo>⋅</mml:mo><mml:mo stretchy="false">(</mml:mo><mml:mfrac><mml:mrow><mml:msub><mml:mi>σ</mml:mi><mml:mi>i</mml:mi></mml:msub><mml:mo>−</mml:mo><mml:mover accent="true"><mml:mi>σ</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:mrow><mml:mover accent="true"><mml:mi>σ</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:mfrac><mml:mo stretchy="false">)</mml:mo><mml:msub><mml:mrow><mml:mover><mml:mstyle mathvariant="bold" mathsize="normal"><mml:mi>n</mml:mi></mml:mstyle><mml:mo>˜</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>x</mml:mi><mml:mo>,</mml:mo><mml:mi>y</mml:mi><mml:mo>,</mml:mo><mml:mi>z</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msub></mml:mrow></mml:math></alternatives><label>(6)</label></disp-formula><disp-formula id="pone.0132552.e011"><alternatives><graphic xlink:href="pone.0132552.e011.jpg" id="pone.0132552.e011g" position="anchor" mimetype="image" orientation="portrait"></graphic><mml:math id="M11"><mml:mrow><mml:mtext> </mml:mtext><mml:mi>M</mml:mi><mml:msubsup><mml:mi>R</mml:mi><mml:mrow><mml:mi>A</mml:mi><mml:mi>d</mml:mi><mml:mi>a</mml:mi><mml:mi>p</mml:mi><mml:mi>t</mml:mi><mml:mi>i</mml:mi><mml:mi>v</mml:mi><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>k</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mi>M</mml:mi><mml:msubsup><mml:mi>R</mml:mi><mml:mrow></mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mn>0</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msubsup><mml:mrow><mml:mo>[</mml:mo><mml:mrow><mml:mfrac><mml:mrow><mml:msubsup><mml:mi>σ</mml:mi><mml:mrow><mml:mtext>max</mml:mtext></mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>k</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msubsup></mml:mrow><mml:mrow><mml:msubsup><mml:mi>σ</mml:mi><mml:mrow><mml:mtext>max</mml:mtext></mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mn>0</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:mfrac></mml:mrow><mml:mo>]</mml:mo></mml:mrow></mml:mrow></mml:math></alternatives><label>(7)</label></disp-formula></sec><sec id="sec006"><title>Design prototype and <italic>in vitro</italic> test</title><p>Computerized additive manufacturing has novel potential in prosthetic fabrication [<xref rid="pone.0132552.ref051" ref-type="bibr">51</xref>], but few reports are currently available in dentistry. In this study, the patient jaw model and both the initial and optimized RPDs were prototyped using 3D printing to demonstrate the integration of CAD with CAM. The mandible was printed with a stereolithography machine (Projet HD 3000; 3D Systems, South Carolina, USA) with 16 μm building layer thickness in Shore 90D polyurethane. The mucosa layer was molded onto the rigid bone model, with Shore 15AF polyurethane. As limited by the printable materials commercially available, the metal frames of both dentures were fabricated with stainless steel 316 GP1 by direct metal laser sintering (EOSINT M 270; EOS, Michigan, USA) at 20 μm per building layer. The artificial teeth and denture base were also over-molded with Shore 30D polyurethane.</p><p>The prototypes were tested <italic>in vitro</italic> to explore the outcomes of the proposed CAD/CAM procedure with a universal testing machine (Instron 3360; Instron, Victoria, Australia). Two <italic>in vitro</italic> experimental methods were used to examine the contact between the denture base of RPD prototypes and the mandibular residual ridge model. The first was to apply white silicone (Fit Checker II; GC Corporation, New South Wales, Australia) for checking the fit, and the second was using a pressure sensitive film (model 4LW; Fuji Film, New South Wales, Australia) to examining the pressure distribution.</p></sec></sec><sec sec-type="results" id="sec007"><title>Results</title><sec id="sec008"><title>Optimization convergence</title><p>Both the maximum contact pressure (MAX) and standard deviation (SD) are plotted in <xref rid="pone.0132552.g003" ref-type="fig">Fig 3a</xref> against the iteration number of the BESO computational design (Details are included in the <xref rid="pone.0132552.s001" ref-type="supplementary-material">S1 Table</xref>). Our algorithm and parameters demonstrated a balance between optimization efficiency and robustness of convergence. Through a smooth convergence trend, the optimization reduces the maximum pressure from 209.2 kPa to 65.6 kPa (by 70%), and improves the uniformity from ± 50.3 kPa to ± 18.4 kPa (by 63%). The computational time for 100 iterations of BESO contact optimization is about a day.</p><fig id="pone.0132552.g003" orientation="portrait" position="float"><object-id pub-id-type="doi">10.1371/journal.pone.0132552.g003</object-id><label>Fig 3</label><caption><p>Convergence history, a) the maximum contact pressure and the deviation of contact pressure (i.e. the objective function <xref rid="pone.0132552.e009" ref-type="disp-formula">Eq (5)</xref>); b) the contact area and the load transferred from denture base during the optimization.</p></caption><graphic xlink:href="pone.0132552.g003"></graphic></fig><p>The variation of the effective contact area and the total load transferred from the denture base to mucosa tissue are plotted in <xref rid="pone.0132552.g003" ref-type="fig">Fig 3b</xref>. An uprising trend shows the increasing effectiveness in the contact surface within a fixed design boundary, and some proportion of the load is shifted from the denture base onto the supportive abutment teeth (premolars) via the clasps and rests.</p></sec><sec id="sec009"><title>Denture modification and contact pressure</title><p><xref rid="pone.0132552.g004" ref-type="fig">Fig 4a</xref> shows the optimal denture shape with the maximum material addition of 382 μm thick and the maximum removal of 224 μm deep. To reduce the cantilever effect of the initial design, more material is added to the mesial end of the denture base, whereas the thickness is reduced at the distal end. The buccal side of the denture is optimized to share more load in this specific patient case for better efficiency. <xref rid="pone.0132552.g004" ref-type="fig">Fig 4b</xref> shows the contours of contact pressures on the denture base before and after the optimization, which clearly exhibit the reduction of pressure concentration severity and improvement in its uniformity. Not only the mesial area, but also the edges of the denture base achieve the improved contact conditions, allowing more effective and smoother load transfer from denture base to mucosa.</p><fig id="pone.0132552.g004" orientation="portrait" position="float"><object-id pub-id-type="doi">10.1371/journal.pone.0132552.g004</object-id><label>Fig 4</label><caption><p>Optimization outcomes, a) the modification made to the denture base through the BESO shape optimization with an adaptive modification rate; the maximum material deposition and removal are 382 and 224 um; b) the contact pressure contours on the initial denture base (left) and the optimized denture base (right).</p></caption><graphic xlink:href="pone.0132552.g004"></graphic></fig></sec><sec id="sec010"><title><italic>In vitro</italic> loading test</title><p><xref rid="pone.0132552.g005" ref-type="fig">Fig 5a</xref> shows the prototyped mandible (upper) alone and with the optimal denture (lower). <xref rid="pone.0132552.g005" ref-type="fig">Fig 5b</xref> illustrates the loading setup for the <italic>in vitro</italic> test, in which the pressure film was inserted between the mandibular residual ridge model and the denture base prototype. The fitting outcomes of white silicone are shown in <xref rid="pone.0132552.g005" ref-type="fig">Fig 5c</xref>, and a tight contact in this test squeezed silicone out to create a blank area (black dash line) under loading. Under the initial denture, a medium layer of silicone indicated insufficient load bearing on the mesial end, as highlighted by the yellow triangles. Through the optimization, the supportive contact area was expanded in the mesial direction, while some distal areas became less effective, indicated by the blue triangles, in these models. Consistent trends were observed with the pressure sensitive film test in <xref rid="pone.0132552.g005" ref-type="fig">Fig 5d</xref>. The initial denture led to stress concentration at the distal end, and this load was re-distributed towards the mesial direction under the optimized denture. It is noted that although <italic>in vivo</italic> mechanical behavior cannot be quantified precisely through these <italic>in vitro</italic> models, the <italic>in vitro</italic> tests provide meaningful assessment of the optimization outcomes without being influenced by physiological factors.</p><fig id="pone.0132552.g005" orientation="portrait" position="float"><object-id pub-id-type="doi">10.1371/journal.pone.0132552.g005</object-id><label>Fig 5</label><caption><p>Prototypes and <italic>in vitro</italic> test, a) the subject jaw model (upper) and the optimized denture (lower); b) <italic>in vitro</italic> loading test performed under Instron, with a pressure sensitive firm between the denture and the jaw; c) the fitting white silicone test; d) the pressure sensitive film test.</p></caption><graphic xlink:href="pone.0132552.g005"></graphic></fig></sec></sec><sec sec-type="conclusions" id="sec011"><title>Discussion</title><sec id="sec012"><title>Pressure-pain threshold (PPT)</title><p>The oral mucosa, being a supportive tissue, is found to be mechanically and physiologically responsive to functional pressure during mastication. Previous research has revealed that high contact pressure can trigger pain in the oral mucosa, and a short term concern lies in discomfort and painful sensation for denture users, which is also associated with denture-related stomatitis [<xref rid="pone.0132552.ref052" ref-type="bibr">52</xref>–<xref rid="pone.0132552.ref054" ref-type="bibr">54</xref>]. A pressure-pain threshold (PPT) was defined as the lowest pressure that causes pain [<xref rid="pone.0132552.ref055" ref-type="bibr">55</xref>, <xref rid="pone.0132552.ref056" ref-type="bibr">56</xref>]; and <xref rid="pone.0132552.g006" ref-type="fig">Fig 6a</xref> compares the clinical PPT data with both averages and standard deviations reported in the literature [<xref rid="pone.0132552.ref003" ref-type="bibr">3</xref>, <xref rid="pone.0132552.ref010" ref-type="bibr">10</xref>, <xref rid="pone.0132552.ref011" ref-type="bibr">11</xref>, <xref rid="pone.0132552.ref041" ref-type="bibr">41</xref>, <xref rid="pone.0132552.ref042" ref-type="bibr">42</xref>, <xref rid="pone.0132552.ref052" ref-type="bibr">52</xref>, <xref rid="pone.0132552.ref055" ref-type="bibr">55</xref>–<xref rid="pone.0132552.ref060" ref-type="bibr">60</xref>] along with our FE modeling results (Details are included in the <xref rid="pone.0132552.s002" ref-type="supplementary-material">S2 Table</xref>). Although the initial FE denture model (baseline) provides a ‘perfect’ morphological match to the mucosa, the maximum contact pressure (209.2 kPa) lies in the mid-range of PPTs. After the optimization, the maximum contact pressure is reduced by nearly 70% (65.6 kPa), which falls well below most PPTs (<italic>p</italic> < 0.01, ANOVA[<xref rid="pone.0132552.ref061" ref-type="bibr">61</xref>], standard deviation <sub>(FE)</sub> = 0).</p><fig id="pone.0132552.g006" orientation="portrait" position="float"><object-id pub-id-type="doi">10.1371/journal.pone.0132552.g006</object-id><label>Fig 6</label><caption><p>Clinical implications, a) the maximum contact pressures induced by both initial and optimized dentures are compared with the clinical pressure-pain thresholds (PPTs) over the distal region of the mandible. The maximum contact pressure (*) under the optimized denture is significantly lower than the PPTs available from literature (<italic>p</italic> < 0.01). b) Hydrostatic pressure induced by the denture insertion through the optimization procedure, indicating the reduction of disturbance severity to the blood circulation.</p></caption><graphic xlink:href="pone.0132552.g006"></graphic></fig></sec><sec id="sec013"><title>Residual ridge resorption (RRR)</title><p>Apart from the immediate pain and discomfort, the long term concern is the consequential residual ridge resorption (RRR), caused by raised interstitial fluid pressure (IFP) or known as hydrostatic pressure inside the mucosa [<xref rid="pone.0132552.ref005" ref-type="bibr">5</xref>, <xref rid="pone.0132552.ref007" ref-type="bibr">7</xref>, <xref rid="pone.0132552.ref008" ref-type="bibr">8</xref>]. The aging edentulous mandible is mainly supported by the periosteal plexus of blood vessels; therefore it is very sensitive to a diminished level of circulation under occlusal load, causing reduced nutrient supply to and metabolite removal from the supporting mandibular bone [<xref rid="pone.0132552.ref062" ref-type="bibr">62</xref>]. Experimental observations have shown that 50 kPa pressure can reduce the blood flow rate to only 21% within 5 seconds, and further reduction to 15% after 30 seconds [<xref rid="pone.0132552.ref063" ref-type="bibr">63</xref>]. The continuously loaded epithelial cells and surrounding tissues, undergo an inflammatory response, contributing to a variation in permeability of the mucosal tissue, and further compromising circulation [<xref rid="pone.0132552.ref041" ref-type="bibr">41</xref>, <xref rid="pone.0132552.ref064" ref-type="bibr">64</xref>]. More recent studies have shown that hydrostatic pressure controls osteogenesis and osteoclastogenesis [<xref rid="pone.0132552.ref065" ref-type="bibr">65</xref>, <xref rid="pone.0132552.ref066" ref-type="bibr">66</xref>], and RRR has been observed at high hydrostatic pressure regions under certain types of dentures [<xref rid="pone.0132552.ref004" ref-type="bibr">4</xref>].</p><p><xref rid="pone.0132552.g006" ref-type="fig">Fig 6b</xref> shows the hydrostatic pressure distribution on the mucosa through the optimization process (Details are included in the <xref rid="pone.0132552.s003" ref-type="supplementary-material">S3 Table</xref>). The maximum hydrostatic pressure was 29.5 kPa for the initial denture, and it decreased to 19.6 kPa (33.5% reduction) after the optimization, where the green-red color (medium to severe disturbance) disappears. More importantly, the distribution has become more uniform on the residual ridge along both mesial-distal and lingual-buccal directions, indicated by the expanded light blue (low disturbance) regions. The magnitude of the hydrostatic pressure indicates the severity of induced disturbance to local blood circulation, showing that the initial high disturbance along the lingual side is eased and more evenly disturbed over the entire optimized contact surface.</p></sec><sec id="sec014"><title>Clinical implications and limitations</title><p>The proposed automatic optimization and fabrication procedure provides an alternative to the conventional manual denture fabrication and fitting, and its advantages can be stated as follows. First, the computerized approaches consider intimate interaction with the oral mucosa and jaw bone, including their anatomical and physiological variations. Early studies have shown that bone is a heterogeneous material with local biomechanical property variations, affecting load transfer and strain [<xref rid="pone.0132552.ref001" ref-type="bibr">1</xref>, <xref rid="pone.0132552.ref006" ref-type="bibr">6</xref>]. The soft tissue also influences the denture masticatory load distribution in a non-linear manner [<xref rid="pone.0132552.ref003" ref-type="bibr">3</xref>–<xref rid="pone.0132552.ref005" ref-type="bibr">5</xref>]. Second, this automatic procedure demonstrated considerable potential in reducing laboratory cost and dependence on clinical skills and experience for individual patient treatment. Despite the proven effectiveness and clinical predictability, the conventional method is facing severe challenges from the ever-growing aging population and demand for denture treatments with shortage of dentists and dental laboratory staff for its labor-intensive nature [<xref rid="pone.0132552.ref067" ref-type="bibr">67</xref>]. These disadvantages are being gradually expunged, such as the need for a minimum of 4 or 5 treatment visits with additional post-insertion follow-ups, high laboratory expenses and time cost [<xref rid="pone.0132552.ref028" ref-type="bibr">28</xref>]. The proposed computer based optimization and additive fabrication procedure may ameliorate these downsides with customized optimal treatment and reduced cost through a computationally automatic process of scan-design-manufacturing. This approach may also benefit the patients with hypersensitive gag reflexes [<xref rid="pone.0132552.ref068" ref-type="bibr">68</xref>, <xref rid="pone.0132552.ref069" ref-type="bibr">69</xref>], who are likely to vomit during impression making in the conventional method. Third, computer based approaches allow offering a consistent accuracy and reliable reproducibility with quantitative guidelines, while the conventional clinical denture fabrication, adjustment and correction are often performed manually [<xref rid="pone.0132552.ref070" ref-type="bibr">70</xref>], with heavy reliance on techniques and experience available [<xref rid="pone.0132552.ref016" ref-type="bibr">16</xref>]. Lastly, this optimization algorithm can benefit patients in both short-term and long-term perspectives, as shown in reduction of immediate pain/discomfort and potential residual ridge resorption, as well as fewer recall visits for denture adjustment.</p><p>There are a few assumptions and limitations in this study. Following the clinical protocol and radiation dosage available, the applied scanning resolution may affect modeling accuracy. The supporting tooth was considered a rigid body without differentiating its individual hard tissues (dentin and enamel), for their less significant differences comparing to the oral mucosa. The other important soft tissue, periodontal ligament, was not included in this study, for its slight thickness beyond the differentiable CT range, and the associated tooth mobility requires further investigation [<xref rid="pone.0132552.ref071" ref-type="bibr">71</xref>]. It would be interesting to explore the effects of different patients (e.g. loading sites, magnitudes, multiple loads, sulcus depth and width, anatomical abnormalities, etc.) and prosthetic conditions (clasp/rest/guide plane design, denture material), for yielding statistical effectiveness of the proposed methods. It is also significant to take into account the consequential bone apposition and resorption activities, but these are beyond the scope of this study.</p><p>As the limitations to our prototypes, there is a certain manufacturing tolerance and materials currently available, leading to differences between the real human oral tissues and the printable model. The in-vitro tests were performed on such prototype models and the results of the contact conditions could only serve as a purpose of demonstrating the integration of CAD/CAM system and effectiveness of the optimization algorithm. Nevertheless, this study showcased a feasible new approach from diagnosed scan, computational modeling and design to additive manufacturing for prosthetic dentistry, thereby providing new technological potential for other dental prosthetic treatments in the future.</p></sec></sec><sec sec-type="conclusions" id="sec015"><title>Conclusions</title><p>This study proposed a fully automatic design optimization and additive fabrication procedure for RPD. The bi-directional evolutionary structural optimization (BESO) technique removes material from the high contact pressure region to lessen the peak contact stress and adds material to under-loaded regions to enhance loading-bearing capacity. The optimized denture base is able to deliver a more evenly distributed contact pressure and reduce the peak pressure, making them well below PPTs. More importantly, the overloaded region was largely reduced via the optimization and a lower hydrostatic pressure was generated, thereby reducing risk of associated long term bone resorption. This proposed computational optimization and additive fabrication procedure demonstrates considerable promise for other dental prostheses, thereby providing quantitative guidelines and computer aided design and manufacturing (CAD/CAM) in the dental clinic for an individual patient.</p></sec><sec sec-type="supplementary-material" id="sec016"><title>Supporting Information</title><supplementary-material content-type="local-data" id="pone.0132552.s001"><label>S1 Table</label><caption><title>Optimization Convergence History through 100 Iterations.</title><p>(PDF)</p></caption><media xlink:href="pone.0132552.s001.pdf"><caption><p>Click here for additional data file.</p></caption></media></supplementary-material><supplementary-material content-type="local-data" id="pone.0132552.s002"><label>S2 Table</label><caption><title>Summary of Literature Pressure-Pain Threshold Data and Comparison of FEA Results before and after Optimization.</title><p>(PDF)</p></caption><media xlink:href="pone.0132552.s002.pdf"><caption><p>Click here for additional data file.</p></caption></media></supplementary-material><supplementary-material content-type="local-data" id="pone.0132552.s003"><label>S3 Table</label><caption><title>Change of Hydrostatic Pressure in the Oral Mucosa through Optimization.</title><p>(PDF)</p></caption><media xlink:href="pone.0132552.s003.pdf"><caption><p>Click here for additional data file.</p></caption></media></supplementary-material></sec></body><back><ref-list><title>References</title><ref id="pone.0132552.ref001"><label>1</label><mixed-citation publication-type="journal"><name><surname>Field</surname><given-names>C</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>, <name><surname>Li</surname><given-names>W</given-names></name>, <name><surname>Thompson</surname><given-names>M</given-names></name>, <name><surname>Swain</surname><given-names>M</given-names></name>. <article-title>Prediction of mandibular bone remodelling induced by fixed partial dentures</article-title>. <source>J Biomech</source><year>2010</year>; <volume>43</volume>: <fpage>1771</fpage>–<lpage>1779</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/j.jbiomech.2010.02.016">10.1016/j.jbiomech.2010.02.016</ext-link></comment><pub-id pub-id-type="pmid">20227698</pub-id></mixed-citation></ref><ref id="pone.0132552.ref002"><label>2</label><mixed-citation publication-type="journal"><name><surname>Kydd</surname><given-names>WL</given-names></name>, <name><surname>Daly</surname><given-names>CH</given-names></name>, <name><surname>Nansen</surname><given-names>D</given-names></name>. <article-title>Variation in the response to mechanical stress of human soft tissues as related to age</article-title>. <source>J Prosthet Dent</source><year>1974</year>; <volume>32</volume>: <fpage>493</fpage>–<lpage>500</lpage>. <pub-id pub-id-type="pmid">4531483</pub-id></mixed-citation></ref><ref id="pone.0132552.ref003"><label>3</label><mixed-citation publication-type="journal"><name><surname>Sawada</surname><given-names>A</given-names></name>, <name><surname>Wakabayashi</surname><given-names>N</given-names></name>, <name><surname>Ona</surname><given-names>M</given-names></name>, <name><surname>Suzuki</surname><given-names>T</given-names></name>. <article-title>Viscoelasticity of Human Oral Mucosa: Implications for Masticatory Biomechanics</article-title>. <source>J Dent Res</source><year>2011</year>; <volume>90</volume>: <fpage>590</fpage>–<lpage>595</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1177/0022034510396881">10.1177/0022034510396881</ext-link></comment><pub-id pub-id-type="pmid">21321067</pub-id></mixed-citation></ref><ref id="pone.0132552.ref004"><label>4</label><mixed-citation publication-type="journal"><name><surname>Ahmad</surname><given-names>R</given-names></name>, <name><surname>Chen</surname><given-names>J</given-names></name>, <name><surname>Abu-Hassan</surname><given-names>MI</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>, <name><surname>Swain</surname><given-names>MV</given-names></name>. <article-title>Investigation of Mucosa-Induced Residual Ridge Resorption between Implant-retained Overdenture and Complete Denture</article-title>. <source>Int J Oral Maxillofac Implants</source><year>2015</year>; <volume>30</volume>: <fpage>657</fpage>–<lpage>666</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.11607/jomi.3844">10.11607/jomi.3844</ext-link></comment><pub-id pub-id-type="pmid">26009917</pub-id></mixed-citation></ref><ref id="pone.0132552.ref005"><label>5</label><mixed-citation publication-type="journal"><name><surname>Mori</surname><given-names>S</given-names></name>, <name><surname>Sato</surname><given-names>T</given-names></name>, <name><surname>Hara</surname><given-names>T</given-names></name>, <name><surname>Nakashima</surname><given-names>K</given-names></name>, <name><surname>Minagi</surname><given-names>S</given-names></name>. <article-title>Effect of continuous pressure on histopathological changes in denture-supporting tissues</article-title>. <source>J Oral Rehabil</source><year>1997</year>; <volume>24</volume>: <fpage>37</fpage>–<lpage>46</lpage>. <pub-id pub-id-type="pmid">9049918</pub-id></mixed-citation></ref><ref id="pone.0132552.ref006"><label>6</label><mixed-citation publication-type="journal"><name><surname>Sato</surname><given-names>T</given-names></name>, <name><surname>Hara</surname><given-names>T</given-names></name>, <name><surname>Mori</surname><given-names>S</given-names></name>, <name><surname>Shirai</surname><given-names>H</given-names></name>, <name><surname>Minagi</surname><given-names>S</given-names></name>. <article-title>Threshold for bone resorption induced by continuous and intermittent pressure in the rat hard palate</article-title>. <source>J Dent Res</source><year>1998</year>; <volume>77</volume>: <fpage>387</fpage>–<lpage>392</lpage>. <pub-id pub-id-type="pmid">9465171</pub-id></mixed-citation></ref><ref id="pone.0132552.ref007"><label>7</label><mixed-citation publication-type="journal"><name><surname>Imai</surname><given-names>Y</given-names></name>, <name><surname>Sato</surname><given-names>T</given-names></name>, <name><surname>Mori</surname><given-names>S</given-names></name>, <name><surname>Okamoto</surname><given-names>M</given-names></name>. <article-title>A histomorphometric analysis on bone dynamics in denture supporting tissue under continuous pressure</article-title>. <source>J Oral Rehabil</source><year>2002</year>; <volume>29</volume>: <fpage>72</fpage>–<lpage>9</lpage>. <pub-id pub-id-type="pmid">11844035</pub-id></mixed-citation></ref><ref id="pone.0132552.ref008"><label>8</label><mixed-citation publication-type="journal"><name><surname>Blum</surname><given-names>IR</given-names></name>, <name><surname>McCord</surname><given-names>JF</given-names></name>. <article-title>A clinical investigation of the morphological changes in the posterior mandible when implant-retained overdentures are used</article-title>. <source>Clin Oral Implants Res</source><year>2004</year>; <volume>15</volume>: <fpage>700</fpage>–<lpage>8</lpage>. <pub-id pub-id-type="pmid">15533131</pub-id></mixed-citation></ref><ref id="pone.0132552.ref009"><label>9</label><mixed-citation publication-type="journal"><name><surname>Carlsson</surname><given-names>GE</given-names></name>. <article-title>Responses of jawbone to pressure</article-title>. <source>Gerodontology</source><year>2004</year>; <volume>21</volume>: <fpage>65</fpage>–<lpage>70</lpage>. <pub-id pub-id-type="pmid">15185985</pub-id></mixed-citation></ref><ref id="pone.0132552.ref010"><label>10</label><mixed-citation publication-type="journal"><name><surname>Suzuki</surname><given-names>Y</given-names></name>, <name><surname>Katoh</surname><given-names>M</given-names></name>, <name><surname>Sato</surname><given-names>J</given-names></name>, <name><surname>Morokuma</surname><given-names>M</given-names></name>, <name><surname>Hosoi</surname><given-names>MA</given-names></name>, <name><surname>Ohkubo</surname><given-names>C</given-names></name>. <article-title>Pressure pain threshold of mucosa after tooth extraction under removable denture bases</article-title>. <source>Eur J Prosthodont Restor Dent</source><year>2011</year>; <volume>19</volume>: <fpage>184</fpage>–<lpage>6</lpage>. <pub-id pub-id-type="pmid">22645806</pub-id></mixed-citation></ref><ref id="pone.0132552.ref011"><label>11</label><mixed-citation publication-type="journal"><name><surname>Ogawa</surname><given-names>T</given-names></name>, <name><surname>Ogimoto</surname><given-names>T</given-names></name>, <name><surname>Sumiyoshi</surname><given-names>K</given-names></name>, <name><surname>Koyano</surname><given-names>K</given-names></name>. <article-title>Pressure-pain threshold of oral mucosa and its region-specific modulation by pre-loading</article-title>. <source>J Oral Rehabil</source><year>2003</year>; <volume>30</volume>: <fpage>1062</fpage>–<lpage>1069</lpage>. <pub-id pub-id-type="pmid">14641669</pub-id></mixed-citation></ref><ref id="pone.0132552.ref012"><label>12</label><mixed-citation publication-type="journal"><name><surname>Bae</surname><given-names>KH</given-names></name>, <name><surname>Kim</surname><given-names>C</given-names></name>, <name><surname>Paik</surname><given-names>DI</given-names></name>, <name><surname>Kim</surname><given-names>JB</given-names></name>. <article-title>A comparison of oral health related quality of life between complete and partial removable denture-wearing older adults in Korea</article-title>. <source>J Oral Rehabil</source><year>2006</year>; <volume>33</volume>: <fpage>317</fpage>–<lpage>322</lpage>. <pub-id pub-id-type="pmid">16629888</pub-id></mixed-citation></ref><ref id="pone.0132552.ref013"><label>13</label><mixed-citation publication-type="journal"><name><surname>Wright</surname><given-names>PS</given-names></name>, <name><surname>Glantz</surname><given-names>PO</given-names></name>, <name><surname>Randow</surname><given-names>K</given-names></name>, <name><surname>Watson</surname><given-names>RM</given-names></name>. <article-title>The effects of fixed and removable implant-stabilised prostheses on posterior mandibular residual ridge resorption</article-title>. <source>Clin Oral Implants Res</source><year>2002</year>; <volume>13</volume>: <fpage>169</fpage>–<lpage>174</lpage>. <pub-id pub-id-type="pmid">11952737</pub-id></mixed-citation></ref><ref id="pone.0132552.ref014"><label>14</label><mixed-citation publication-type="journal"><name><surname>Maruo</surname><given-names>Y</given-names></name>, <name><surname>Nishigawa</surname><given-names>G</given-names></name>, <name><surname>Irie</surname><given-names>M</given-names></name>, <name><surname>Oka</surname><given-names>M</given-names></name>, <name><surname>Hara</surname><given-names>T</given-names></name>, <name><surname>Suzuki</surname><given-names>K</given-names></name>, <etal>et al</etal><article-title>Stress distribution prevents ischaemia and bone resorption in residual ridge</article-title>. <source>Arch Oral Biol</source><year>2010</year>; <volume>55</volume>: <fpage>873</fpage>–<lpage>878</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/j.archoralbio.2010.07.022">10.1016/j.archoralbio.2010.07.022</ext-link></comment><pub-id pub-id-type="pmid">20801425</pub-id></mixed-citation></ref><ref id="pone.0132552.ref015"><label>15</label><mixed-citation publication-type="journal"><name><surname>Bail</surname><given-names>M</given-names></name>, <name><surname>Meister</surname><given-names>LMB</given-names></name>, <name><surname>Campagnoli</surname><given-names>EB</given-names></name>, <name><surname>Jorge</surname><given-names>JH</given-names></name>, <name><surname>Ban</surname><given-names>MdCI</given-names></name>, <name><surname>Sanchez-Ayala</surname><given-names>A</given-names></name>, <etal>et al</etal><article-title>Histopathological Changes by the Use of Soft Reline Materials: A Rat Model Study</article-title>. <source>PLoS One</source><year>2014</year>; <volume>9</volume>: <fpage>e100293</fpage><comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1371/journal.pone.0100293">10.1371/journal.pone.0100293</ext-link></comment><pub-id pub-id-type="pmid">24963657</pub-id></mixed-citation></ref><ref id="pone.0132552.ref016"><label>16</label><mixed-citation publication-type="journal"><name><surname>Lee</surname><given-names>C-J</given-names></name>, <name><surname>Bok</surname><given-names>S-B</given-names></name>, <name><surname>Bae</surname><given-names>J-Y</given-names></name>, <name><surname>Lee</surname><given-names>H-H</given-names></name>. <article-title>Comparative adaptation accuracy of acrylic denture bases evaluated by two different methods</article-title>. <source>Dent Mater J</source><year>2010</year>; <volume>29</volume>: <fpage>411</fpage>–<lpage>417</lpage>. <pub-id pub-id-type="pmid">20675954</pub-id></mixed-citation></ref><ref id="pone.0132552.ref017"><label>17</label><mixed-citation publication-type="journal"><name><surname>Rodrigues</surname><given-names>RCS</given-names></name>, <name><surname>Faria</surname><given-names>ACL</given-names></name>, <name><surname>Macedo</surname><given-names>AP</given-names></name>, <name><surname>de Mattos</surname><given-names>MdGC</given-names></name>, <name><surname>Ribeiro</surname><given-names>RF</given-names></name>. <article-title>Retention and stress distribution in distal extension removable partial dentures with and without implant association</article-title>. <source>J Prosthodont Res</source><year>2013</year>; <volume>57</volume>: <fpage>24</fpage>–<lpage>9</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/j.jpor.2012.07.001">10.1016/j.jpor.2012.07.001</ext-link></comment><pub-id pub-id-type="pmid">23200090</pub-id></mixed-citation></ref><ref id="pone.0132552.ref018"><label>18</label><mixed-citation publication-type="journal"><name><surname>Hyde</surname><given-names>TP</given-names></name>, <name><surname>Craddock</surname><given-names>HL</given-names></name>, <name><surname>Blance</surname><given-names>A</given-names></name>, <name><surname>Brunton</surname><given-names>PA</given-names></name>. <article-title>A cross-over Randomised Controlled Trial of selective pressure impressions for lower complete dentures</article-title>. <source>J Dent</source><year>2010</year>; <volume>38</volume>: <fpage>853</fpage>–<lpage>858</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/j.jdent.2010.07.003">10.1016/j.jdent.2010.07.003</ext-link></comment><pub-id pub-id-type="pmid">20637826</pub-id></mixed-citation></ref><ref id="pone.0132552.ref019"><label>19</label><mixed-citation publication-type="journal"><name><surname>Lawson</surname><given-names>WA</given-names></name>. <article-title>Current concepts and practice in complete dentures—impressions—principles and practice</article-title>. <source>J Dent</source><year>1978</year>; <volume>6</volume>: <fpage>43</fpage>–<lpage>58</lpage>. <pub-id pub-id-type="pmid">350925</pub-id></mixed-citation></ref><ref id="pone.0132552.ref020"><label>20</label><mixed-citation publication-type="journal"><name><surname>Kanbara</surname><given-names>R</given-names></name>, <name><surname>Nakamura</surname><given-names>Y</given-names></name>, <name><surname>Ochiai</surname><given-names>KT</given-names></name>, <name><surname>Kawai</surname><given-names>T</given-names></name>, <name><surname>Tanaka</surname><given-names>Y</given-names></name>. <article-title>Three-dimensional finite element stress analysis: The technique and methodology of non-linear property simulation and soft tissue loading behavior for different partial denture designs</article-title>. <source>Dent Mater J</source><year>2012</year>; <volume>31</volume>: <fpage>297</fpage>–<lpage>308</lpage>. <pub-id pub-id-type="pmid">22447065</pub-id></mixed-citation></ref><ref id="pone.0132552.ref021"><label>21</label><mixed-citation publication-type="journal"><name><surname>Archangelo</surname><given-names>CM</given-names></name>, <name><surname>Rocha</surname><given-names>EP</given-names></name>, <name><surname>Pereira</surname><given-names>JA</given-names></name>, <name><surname>Martin Junior</surname><given-names>M</given-names></name>, <name><surname>Anchieta</surname><given-names>RB</given-names></name>, <name><surname>Freitas Junior</surname><given-names>AC</given-names></name>. <article-title>Periodontal ligament influence on the stress distribution in a removable partial denture supported by implant: a finite element analysis</article-title>. <source>J Appl Oral Sci</source><year>2012</year>; <volume>20</volume>: <fpage>362</fpage>–<lpage>368</lpage>. <pub-id pub-id-type="pmid">22858705</pub-id></mixed-citation></ref><ref id="pone.0132552.ref022"><label>22</label><mixed-citation publication-type="journal"><name><surname>Muraki</surname><given-names>H</given-names></name>, <name><surname>Wakabayashi</surname><given-names>N</given-names></name>, <name><surname>Park</surname><given-names>I</given-names></name>, <name><surname>Ohyama</surname><given-names>T</given-names></name>. <article-title>Finite element contact stress analysis of the RPD abutment tooth and periodontal ligament</article-title>. <source>J Dent</source><year>2004</year>; <volume>32</volume>: <fpage>659</fpage>–<lpage>665</lpage>. <pub-id pub-id-type="pmid">15476961</pub-id></mixed-citation></ref><ref id="pone.0132552.ref023"><label>23</label><mixed-citation publication-type="journal"><name><surname>Li</surname><given-names>W</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>, <name><surname>Steven</surname><given-names>GP</given-names></name>, <name><surname>Xie</surname><given-names>YM</given-names></name>. <article-title>An evolutionary approach to elastic contact optimization of frame structures</article-title>. <source>Finite Elem Anal Des</source><year>2003</year>; <volume>40</volume>: <fpage>61</fpage>–<lpage>81</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref024"><label>24</label><mixed-citation publication-type="journal"><name><surname>Li</surname><given-names>W</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>, <name><surname>Steven</surname><given-names>GP</given-names></name>, <name><surname>Xie</surname><given-names>YM</given-names></name>. <article-title>An evolutionary shape optimization for elastic contact problems subject to multiple load cases</article-title>. <source>Comput Method Appl M</source><year>2005</year>; <volume>194</volume>: <fpage>3394</fpage>–<lpage>3415</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref025"><label>25</label><mixed-citation publication-type="journal"><name><surname>Li</surname><given-names>W</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>, <name><surname>Steven</surname><given-names>GP</given-names></name>, <name><surname>Xie</surname><given-names>YM</given-names></name>. <article-title>An evolutionary shape optimization procedure for contact problems in mechanical designs</article-title>. <source>P I Mech Eng C-J Mec</source><year>2003</year>; <volume>217</volume>: <fpage>435</fpage>–<lpage>446</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref026"><label>26</label><mixed-citation publication-type="journal"><name><surname>Li</surname><given-names>Q</given-names></name>, <name><surname>Steven</surname><given-names>GP</given-names></name>, <name><surname>Querin</surname><given-names>OM</given-names></name>, <name><surname>Xie</surname><given-names>YM</given-names></name>. <article-title>Stress based optimization of torsional shafts using an evolutionary procedure</article-title>. <source>Int J Solids Struct</source><year>2001</year>; <volume>38</volume>: <fpage>5661</fpage>–<lpage>5677</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref027"><label>27</label><mixed-citation publication-type="journal"><name><surname>Chang</surname><given-names>CC</given-names></name>, <name><surname>Lee</surname><given-names>MY</given-names></name>, <name><surname>Wang</surname><given-names>SH</given-names></name>. <article-title>Digital denture manufacturing-An integrated technologies of abrasive computer tomography, CNC machining and rapid prototyping</article-title>. <source>Int J Adv Manuf Tech</source><year>2006</year>; <volume>31</volume>: <fpage>41</fpage>–<lpage>49</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref028"><label>28</label><mixed-citation publication-type="journal"><name><surname>Bidra</surname><given-names>AS</given-names></name>, <name><surname>Taylor</surname><given-names>TD</given-names></name>, <name><surname>Agar</surname><given-names>JR</given-names></name>. <article-title>Computer-adided technology for fabricating complete dentures: systematic review of historical background, current status, and future perspectives</article-title>. <source>J Prosthet Dent</source><year>2013</year>; <volume>109</volume>: <fpage>361</fpage>–<lpage>366</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/S0022-3913(13)60318-2">10.1016/S0022-3913(13)60318-2</ext-link></comment><pub-id pub-id-type="pmid">23763779</pub-id></mixed-citation></ref><ref id="pone.0132552.ref029"><label>29</label><mixed-citation publication-type="journal"><name><surname>Butscher</surname><given-names>A</given-names></name>, <name><surname>Bohner</surname><given-names>M</given-names></name>, <name><surname>Doebelin</surname><given-names>N</given-names></name>, <name><surname>Hofmann</surname><given-names>S</given-names></name>, <name><surname>Mueller</surname><given-names>R</given-names></name>. <article-title>New depowdering-friendly designs for three-dimensional printing of calcium phosphate bone substitutes</article-title>. <source>Acta Biomater</source><year>2013</year>; <volume>9</volume>: <fpage>9149</fpage>–<lpage>9158</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/j.actbio.2013.07.019">10.1016/j.actbio.2013.07.019</ext-link></comment><pub-id pub-id-type="pmid">23891808</pub-id></mixed-citation></ref><ref id="pone.0132552.ref030"><label>30</label><mixed-citation publication-type="journal"><name><surname>Farzadi</surname><given-names>A</given-names></name>, <name><surname>Solati-Hashjin</surname><given-names>M</given-names></name>, <name><surname>Asadi-Eydivand</surname><given-names>M</given-names></name>, <name><surname>Abu Osman</surname><given-names>NA</given-names></name>. <article-title>Effect of Layer Thickness and Printing Orientation on Mechanical Properties and Dimensional Accuracy of 3D Printed Porous Samples for Bone Tissue Engineering</article-title>. <source>PLoS One</source><year>2014</year>; <volume>9</volume>: <fpage>e108252</fpage><comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1371/journal.pone.0108252">10.1371/journal.pone.0108252</ext-link></comment><pub-id pub-id-type="pmid">25233468</pub-id></mixed-citation></ref><ref id="pone.0132552.ref031"><label>31</label><mixed-citation publication-type="journal"><name><surname>Chen</surname><given-names>J</given-names></name>, <name><surname>Li</surname><given-names>W</given-names></name>, <name><surname>Swain</surname><given-names>MV</given-names></name>, <name><surname>Ali Darendeliler</surname><given-names>M</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>. <article-title>A periodontal ligament driven remodeling algorithm for orthodontic tooth movement</article-title>. <source>J Biomech</source><year>2014</year>; <volume>47</volume>: <fpage>1689</fpage>–<lpage>1695</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/j.jbiomech.2014.02.030">10.1016/j.jbiomech.2014.02.030</ext-link></comment><pub-id pub-id-type="pmid">24703301</pub-id></mixed-citation></ref><ref id="pone.0132552.ref032"><label>32</label><mixed-citation publication-type="journal"><name><surname>Li</surname><given-names>W</given-names></name>, <name><surname>Swain</surname><given-names>MV</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>, <name><surname>Ironside</surname><given-names>J</given-names></name>, <name><surname>Steven</surname><given-names>GP</given-names></name>. <article-title>Fibre reinforced composite dental bridge. Part II: numerical investigation</article-title>. <source>Biomaterials</source><year>2004</year>; <volume>25</volume>: <fpage>4995</fpage>–<lpage>5001</lpage>. <pub-id pub-id-type="pmid">15109861</pub-id></mixed-citation></ref><ref id="pone.0132552.ref033"><label>33</label><mixed-citation publication-type="journal"><name><surname>Li</surname><given-names>W</given-names></name>, <name><surname>Swain</surname><given-names>MV</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>, <name><surname>Steven</surname><given-names>GP</given-names></name>. <article-title>Towards automated 3D finite element modeling of direct fiber reinforced composite dental bridge</article-title>. <source>J Biomed Mater Res-B: Applied Biomaterials</source><year>2005</year>; <volume>74B</volume>: <fpage>520</fpage>–<lpage>528</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref034"><label>34</label><mixed-citation publication-type="journal"><name><surname>Chen</surname><given-names>J</given-names></name>, <name><surname>Rungsiyakull</surname><given-names>C</given-names></name>, <name><surname>Li</surname><given-names>W</given-names></name>, <name><surname>Chen</surname><given-names>Y</given-names></name>, <name><surname>Swain</surname><given-names>M</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>. <article-title>Multiscale design of surface morphological gradient for osseointegration</article-title>. <source>J Mech Behav Biomed Mater</source><year>2013</year>; <volume>20</volume>: <fpage>387</fpage>–<lpage>97</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/j.jmbbm.2012.08.019">10.1016/j.jmbbm.2012.08.019</ext-link></comment><pub-id pub-id-type="pmid">23523124</pub-id></mixed-citation></ref><ref id="pone.0132552.ref035"><label>35</label><mixed-citation publication-type="journal"><name><surname>Sato</surname><given-names>Y</given-names></name>, <name><surname>Abe</surname><given-names>Y</given-names></name>, <name><surname>Okane</surname><given-names>H</given-names></name>, <name><surname>Tsuga</surname><given-names>K</given-names></name>. <article-title>Finite element analysis of stress relaxation in soft denture liner</article-title>. <source>J Oral Rehabil</source><year>2000</year>; <volume>27</volume>: <fpage>660</fpage>–<lpage>663</lpage>. <pub-id pub-id-type="pmid">10931260</pub-id></mixed-citation></ref><ref id="pone.0132552.ref036"><label>36</label><mixed-citation publication-type="journal"><name><surname>Kupczik</surname><given-names>K</given-names></name>, <name><surname>Chattah</surname><given-names>NLT</given-names></name>. <article-title>The Adaptive Significance of Enamel Loss in the Mandibular Incisors of Cercopithecine Primates (Mammalia: Cercopithecidae): A Finite Element Modelling Study</article-title>. <source>PLoS One</source><year>2014</year>; <volume>9</volume>: <fpage>e97677</fpage><comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1371/journal.pone.0097677">10.1371/journal.pone.0097677</ext-link></comment><pub-id pub-id-type="pmid">24831704</pub-id></mixed-citation></ref><ref id="pone.0132552.ref037"><label>37</label><mixed-citation publication-type="journal"><name><surname>Karim</surname><given-names>L</given-names></name>, <name><surname>Vashishth</surname><given-names>D</given-names></name>. <article-title>Heterogeneous Glycation of Cancellous Bone and Its Association with Bone Quality and Fragility</article-title>. <source>PLoS One</source><year>2012</year>; <volume>7</volume>: <fpage>e35047</fpage><comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1371/journal.pone.0035047">10.1371/journal.pone.0035047</ext-link></comment><pub-id pub-id-type="pmid">22514706</pub-id></mixed-citation></ref><ref id="pone.0132552.ref038"><label>38</label><mixed-citation publication-type="journal"><name><surname>Zaw</surname><given-names>K</given-names></name>, <name><surname>Liu</surname><given-names>GR</given-names></name>, <name><surname>Deng</surname><given-names>B</given-names></name>, <name><surname>Tan</surname><given-names>KBC</given-names></name>. <article-title>Rapid identification of elastic modulus of the interface tissue on dental implants surfaces using reduced-basis method and a neural network</article-title>. <source>J Biomech</source><year>2009</year>; <volume>42</volume>: <fpage>634</fpage>–<lpage>641</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/j.jbiomech.2008.12.001">10.1016/j.jbiomech.2008.12.001</ext-link></comment><pub-id pub-id-type="pmid">19171345</pub-id></mixed-citation></ref><ref id="pone.0132552.ref039"><label>39</label><mixed-citation publication-type="journal"><name><surname>Carter</surname><given-names>DR</given-names></name>, <name><surname>Hayes</surname><given-names>WC</given-names></name>. <article-title>Compressive Behaviour of Bone as a 2-Phase Porous Structure</article-title>. <source>JBone Joint Surg-Am</source><year>1977</year>; <volume>59</volume>: <fpage>954</fpage>–<lpage>962</lpage>.<pub-id pub-id-type="pmid">561786</pub-id></mixed-citation></ref><ref id="pone.0132552.ref040"><label>40</label><mixed-citation publication-type="journal"><name><surname>Sarrafpour</surname><given-names>B</given-names></name>, <name><surname>Swain</surname><given-names>M</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>, <name><surname>Zoellner</surname><given-names>H</given-names></name>. <article-title>Tooth eruption results from bone remodelling driven by bite forces sensed by soft tissue dental follicles: a finite element analysis</article-title>. <source>PLoS ONE</source><year>2013</year>; <volume>8</volume>: <fpage>e58803</fpage><comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1371/journal.pone.0058803">10.1371/journal.pone.0058803</ext-link></comment><pub-id pub-id-type="pmid">23554928</pub-id></mixed-citation></ref><ref id="pone.0132552.ref041"><label>41</label><mixed-citation publication-type="journal"><name><surname>Kydd</surname><given-names>WL</given-names></name>, <name><surname>Daly</surname><given-names>CH</given-names></name>. <article-title>The biologic and mechanical effects of stress on oral mucosa</article-title>. <source>J Prosthet Dent</source><year>1982</year>; <volume>47</volume>: <fpage>317</fpage>–<lpage>29</lpage>. <pub-id pub-id-type="pmid">7038105</pub-id></mixed-citation></ref><ref id="pone.0132552.ref042"><label>42</label><mixed-citation publication-type="journal"><name><surname>Kishi</surname><given-names>M</given-names></name>. <article-title>Experimental studies on the relation between area and displacement of loading surfaces in connection with displaceability in the mucosa of edentulous alveolar ridge under pressure</article-title>. <source>Shika gakuho. Dental science reports</source><year>1972</year>; <volume>72</volume>: <fpage>1043</fpage>–<lpage>1071</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref043"><label>43</label><mixed-citation publication-type="journal"><name><surname>Bergomi</surname><given-names>M</given-names></name>, <name><surname>Cugnoni</surname><given-names>J</given-names></name>, <name><surname>Galli</surname><given-names>M</given-names></name>, <name><surname>Botsis</surname><given-names>J</given-names></name>, <name><surname>Belser</surname><given-names>UC</given-names></name>, <name><surname>Wiskott</surname><given-names>HWA</given-names></name>. <article-title>Hydro-mechanical coupling in the periodontal ligament: A porohyperelastic finite element model</article-title>. <source>J Biomech</source><year>2011</year>; <volume>44</volume>: <fpage>34</fpage>–<lpage>38</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/j.jbiomech.2010.08.019">10.1016/j.jbiomech.2010.08.019</ext-link></comment><pub-id pub-id-type="pmid">20825940</pub-id></mixed-citation></ref><ref id="pone.0132552.ref044"><label>44</label><mixed-citation publication-type="journal"><name><surname>Itoh</surname><given-names>H</given-names></name>, <name><surname>Caputo</surname><given-names>AA</given-names></name>, <name><surname>Wylie</surname><given-names>R</given-names></name>, <name><surname>Berg</surname><given-names>T</given-names></name>. <article-title>Effects of periodontal support and fixed splinting on load transfer by removable partial dentures</article-title>. <source>J Prosthet Dent</source><year>1998</year>; <volume>79</volume>: <fpage>465</fpage>–<lpage>471</lpage>. <pub-id pub-id-type="pmid">9576324</pub-id></mixed-citation></ref><ref id="pone.0132552.ref045"><label>45</label><mixed-citation publication-type="journal"><name><surname>Hart</surname><given-names>RT</given-names></name>, <name><surname>Hennebel</surname><given-names>VV</given-names></name>, <name><surname>Thongpreda</surname><given-names>N</given-names></name>, <name><surname>Vanbuskirk</surname><given-names>WC</given-names></name>, <name><surname>Anderson</surname><given-names>RC</given-names></name>. <article-title>Modeling the Biomechanics of the Mandible: a 3-Dimensional Finite-Element Study</article-title>. <source>J Biomech</source><year>1992</year>; <volume>25</volume>: <fpage>261</fpage>–<lpage>286</lpage>. <pub-id pub-id-type="pmid">1564061</pub-id></mixed-citation></ref><ref id="pone.0132552.ref046"><label>46</label><mixed-citation publication-type="journal"><name><surname>Korioth</surname><given-names>TWP</given-names></name>, <name><surname>Romilly</surname><given-names>DP</given-names></name>, <name><surname>Hannam</surname><given-names>AG</given-names></name>. <article-title>3-Dimensional Finite Element Stress-Analysis of the Dentate Human Mandible</article-title>. <source>Am J Phys Anthropol</source><year>1992</year>; <volume>88</volume>: <fpage>69</fpage>–<lpage>96</lpage>. <pub-id pub-id-type="pmid">1510115</pub-id></mixed-citation></ref><ref id="pone.0132552.ref047"><label>47</label><mixed-citation publication-type="journal"><name><surname>Prinz</surname><given-names>JF</given-names></name>, <name><surname>de Wijk</surname><given-names>RA</given-names></name>, <name><surname>Huntjens</surname><given-names>L</given-names></name>. <article-title>Load dependency of the coefficient of friction of oral mucosa</article-title>. <source>Food Hydrocoll</source><year>2007</year>; <volume>21</volume>: <fpage>402</fpage>–<lpage>408</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref048"><label>48</label><mixed-citation publication-type="journal"><name><surname>Sajewicz</surname><given-names>E</given-names></name>. <article-title>Effect of saliva viscosity on tribological behaviour of tooth enamel</article-title>. <source>Tribol Int</source><year>2009</year>; <volume>42</volume>: <fpage>327</fpage>–<lpage>332</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref049"><label>49</label><mixed-citation publication-type="journal"><name><surname>Chen</surname><given-names>J</given-names></name>, <name><surname>Suenaga</surname><given-names>H</given-names></name>, <name><surname>Hogg</surname><given-names>M</given-names></name>, <name><surname>Li</surname><given-names>W</given-names></name>, <name><surname>Swain</surname><given-names>M</given-names></name>, <name><surname>Li</surname><given-names>Q</given-names></name>. <article-title>Determination of oral mucosal Poisson's ratio and coefficient of friction from in-vivo contact pressure measurements</article-title>. <source>Comput Method Biomec</source>, <year>2015</year>. In Press.</mixed-citation></ref><ref id="pone.0132552.ref050"><label>50</label><mixed-citation publication-type="journal"><name><surname>Rozvany</surname><given-names>GIN</given-names></name>. <article-title>A critical review of established methods of structural topology optimization</article-title>. <source>Struct Multidiscip O</source><year>2009</year>; <volume>37</volume>: <fpage>217</fpage>–<lpage>237</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref051"><label>51</label><mixed-citation publication-type="journal"><name><surname>Inokoshi</surname><given-names>M</given-names></name>, <name><surname>Kanazawa</surname><given-names>M</given-names></name>, <name><surname>Minakuchi</surname><given-names>S</given-names></name>. <article-title>Evaluation of a complete denture trial method applying rapid prototyping</article-title>. <source>Dent Mater J</source><year>2012</year>; <volume>31</volume>: <fpage>40</fpage>–<lpage>46</lpage>. <pub-id pub-id-type="pmid">22277604</pub-id></mixed-citation></ref><ref id="pone.0132552.ref052"><label>52</label><mixed-citation publication-type="journal"><name><surname>McMillian</surname><given-names>AS</given-names></name>. <article-title>Pain-pressure threshold in human gingivae</article-title>. <source>J Orofac Pain</source><year>1995</year>; <volume>9</volume>: <fpage>44</fpage>–<lpage>50</lpage>. <pub-id pub-id-type="pmid">7581204</pub-id></mixed-citation></ref><ref id="pone.0132552.ref053"><label>53</label><mixed-citation publication-type="journal"><name><surname>Davenpor</surname><given-names>JC</given-names></name>. <article-title>Pressure-pain thresholds in oral cavity in man</article-title>. <source>Arch Oral Biol</source><year>1969</year>; <volume>14</volume>: <fpage>1267-&</fpage><pub-id pub-id-type="pmid">5260890</pub-id></mixed-citation></ref><ref id="pone.0132552.ref054"><label>54</label><mixed-citation publication-type="journal"><name><surname>Kubo</surname><given-names>K</given-names></name>, <name><surname>Kawata</surname><given-names>T</given-names></name>, <name><surname>Suenaga</surname><given-names>H</given-names></name>, <name><surname>Yoda</surname><given-names>N</given-names></name>, <name><surname>Shigemitsu</surname><given-names>R</given-names></name>, <name><surname>Ogawa</surname><given-names>T</given-names></name>, <etal>et al</etal><article-title>Development of <italic>in vivo</italic> measuring system of the pressure distribution under the denture base of removable partial denture</article-title>. <source>J Prosthodont Res</source><year>2009</year>; <volume>53</volume>: <fpage>15</fpage>–<lpage>21</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1016/j.jpor.2008.08.006">10.1016/j.jpor.2008.08.006</ext-link></comment><pub-id pub-id-type="pmid">19318066</pub-id></mixed-citation></ref><ref id="pone.0132552.ref055"><label>55</label><mixed-citation publication-type="journal"><name><surname>Ogimoto</surname><given-names>T</given-names></name>, <name><surname>Ogawa</surname><given-names>T</given-names></name>, <name><surname>Sumiyoshi</surname><given-names>K</given-names></name>, <name><surname>Matsuka</surname><given-names>Y</given-names></name>, <name><surname>Koyano</surname><given-names>K</given-names></name>. <article-title>Pressure-pain threshold determination in the oral mucosa: validity and reliability</article-title>. <source>J Oral Rehabil</source><year>2002</year>; <volume>29</volume>: <fpage>620</fpage>–<lpage>626</lpage>. <pub-id pub-id-type="pmid">12153450</pub-id></mixed-citation></ref><ref id="pone.0132552.ref056"><label>56</label><mixed-citation publication-type="journal"><name><surname>List</surname><given-names>T</given-names></name>, <name><surname>Helkimo</surname><given-names>M</given-names></name>, <name><surname>Karlsson</surname><given-names>R</given-names></name>. <article-title>Influence of pressure rates on the reliability of a pressure threshold meter</article-title>. <source>J Craniomandib Disord</source><year>1991</year>; <volume>5</volume>: <fpage>173</fpage>–<lpage>178</lpage>. <pub-id pub-id-type="pmid">1812145</pub-id></mixed-citation></ref><ref id="pone.0132552.ref057"><label>57</label><mixed-citation publication-type="journal"><name><surname>Scapino</surname><given-names>RP</given-names></name>. <article-title>Biomechanics of Prehensile Oral Mucosa</article-title>. <source>J Morphol</source><year>1967</year>; <volume>122</volume>: <fpage>89</fpage>–<lpage>113</lpage>. <pub-id pub-id-type="pmid">6040566</pub-id></mixed-citation></ref><ref id="pone.0132552.ref058"><label>58</label><mixed-citation publication-type="journal"><name><surname>Wakabayashi</surname><given-names>N</given-names></name>, <name><surname>Suzuki</surname><given-names>T</given-names></name>. <article-title>Patient-specific finite element analysis of viscoelastic masticatory mucosa</article-title>. <source>J Dent Biomech</source><year>2013</year>; <volume>4</volume>.</mixed-citation></ref><ref id="pone.0132552.ref059"><label>59</label><mixed-citation publication-type="journal"><name><surname>Ogawa</surname><given-names>T</given-names></name>, <name><surname>Tanaka</surname><given-names>M</given-names></name>, <name><surname>Ogimoto</surname><given-names>T</given-names></name>, <name><surname>Okushi</surname><given-names>N</given-names></name>, <name><surname>Koyano</surname><given-names>K</given-names></name>, <name><surname>Takeuchi</surname><given-names>K</given-names></name>. <article-title>Mapping, profiling and clustering of pressure pain threshold (PPT) in edentulous oral mucosa</article-title>. <source>J Dent</source><year>2004</year>; <volume>32</volume>: <fpage>219</fpage>–<lpage>228</lpage>. <pub-id pub-id-type="pmid">15001287</pub-id></mixed-citation></ref><ref id="pone.0132552.ref060"><label>60</label><mixed-citation publication-type="journal"><name><surname>Tanaka</surname><given-names>M</given-names></name>, <name><surname>Ogimoto</surname><given-names>T</given-names></name>, <name><surname>Koyano</surname><given-names>K</given-names></name>, <name><surname>Ogawa</surname><given-names>T</given-names></name>. <article-title>Denture wearing and strong bite force reduce pressure pain threshold of edentulous oral mucosa</article-title>. <source>J Oral Rehabil</source><year>2004</year>; <volume>31</volume>: <fpage>873</fpage>–<lpage>878</lpage>. <pub-id pub-id-type="pmid">15369468</pub-id></mixed-citation></ref><ref id="pone.0132552.ref061"><label>61</label><mixed-citation publication-type="journal"><name><surname>Mycroft</surname><given-names>RH</given-names></name>, <name><surname>Mitchell</surname><given-names>DC</given-names></name>, <name><surname>Kay</surname><given-names>J</given-names></name>. <article-title>An evaluation of statistical procedures for comparing an individual's performance with that of a group of controls</article-title>. <source>Cogn Neuropsychol</source><year>2002</year>; <volume>19</volume>: <fpage>291</fpage>–<lpage>299</lpage>. <comment>doi: <ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1080/02643290143000150">10.1080/02643290143000150</ext-link></comment><pub-id pub-id-type="pmid">20957541</pub-id></mixed-citation></ref><ref id="pone.0132552.ref062"><label>62</label><mixed-citation publication-type="journal"><name><surname>Bradley</surname><given-names>JC</given-names></name>. <article-title>The clinical significance of age changes in the vascular supply to the mandible</article-title>. <source>Int J Oral Surg</source><year>1981</year>; <volume>10</volume>: <fpage>71</fpage>–<lpage>76</lpage>. <pub-id pub-id-type="pmid">6807911</pub-id></mixed-citation></ref><ref id="pone.0132552.ref063"><label>63</label><mixed-citation publication-type="journal"><name><surname>Akazawa</surname><given-names>H</given-names></name>, <name><surname>Sakurai</surname><given-names>K</given-names></name>. <article-title>Changes of blood flow in the mucosa underlying a mandibular denture following pressure assumed as a result of light clenching</article-title>. <source>J Oral Rehabil</source><year>2002</year>; <volume>29</volume>: <fpage>336</fpage>–<lpage>340</lpage>. <pub-id pub-id-type="pmid">11966966</pub-id></mixed-citation></ref><ref id="pone.0132552.ref064"><label>64</label><mixed-citation publication-type="journal"><name><surname>Ashton</surname><given-names>H</given-names></name>. <article-title>Effect of increased tissue pressure on blood flow</article-title>. <source>Clin Orthop</source><year>1975</year>: <fpage>15</fpage>–<lpage>26</lpage>.<pub-id pub-id-type="pmid">1192660</pub-id></mixed-citation></ref><ref id="pone.0132552.ref065"><label>65</label><mixed-citation publication-type="journal"><name><surname>Kim</surname><given-names>SH</given-names></name>, <name><surname>Park</surname><given-names>SH</given-names></name>, <name><surname>Jun</surname><given-names>JW</given-names></name>, <name><surname>Kim</surname><given-names>DH</given-names></name>, <name><surname>Shin</surname><given-names>JW</given-names></name>, <name><surname>Han</surname><given-names>JY</given-names></name>, <etal>et al</etal><article-title>Hydrostatic Pressure can Control Osteogenesis and Osteoclastogenesis when Stromal Cells and Osteoclast Precursor Cells are Cocultured</article-title>. <source>Tissue Eng Regen Med</source><year>2010</year>; <volume>7</volume>: <fpage>388</fpage>–<lpage>394</lpage>.</mixed-citation></ref><ref id="pone.0132552.ref066"><label>66</label><mixed-citation publication-type="journal"><name><surname>Aspenberg</surname><given-names>P</given-names></name>, <name><surname>van der Vis</surname><given-names>H</given-names></name>. <article-title>Fluid pressure may cause periprosthetic osteolysis—Particles are not the only thing</article-title>. <source>Acta Orthop Scand</source><year>1998</year>; <volume>69</volume>: <fpage>1</fpage>–<lpage>4</lpage>. <pub-id pub-id-type="pmid">9524506</pub-id></mixed-citation></ref><ref id="pone.0132552.ref067"><label>67</label><mixed-citation publication-type="journal"><name><surname>Hill</surname><given-names>EE</given-names></name>, <name><surname>Breeding</surname><given-names>LC</given-names></name>. <article-title>Who Is Teaching Undergraduate Prosthodontics in US Dental Schools, 2007?</article-title><source>JProsthodont</source><year>2009</year>; <volume>18</volume>: <fpage>195</fpage>–<lpage>198</lpage>.<pub-id pub-id-type="pmid">19178621</pub-id></mixed-citation></ref><ref id="pone.0132552.ref068"><label>68</label><mixed-citation publication-type="journal"><name><surname>Jain</surname><given-names>A</given-names></name>, <name><surname>V</surname><given-names>V</given-names></name>, <name><surname>Bharathi</surname><given-names>RM</given-names></name>, <name><surname>Patil</surname><given-names>V</given-names></name>, <name><surname>Alur</surname><given-names>J</given-names></name>. <article-title>Management of severe gag reflex by an unique approach: palateless dentures</article-title>. <source>JClin Diagn Res</source><year>2013</year>; <volume>7</volume>:<fpage>2394</fpage>–<lpage>5</lpage><pub-id pub-id-type="pmid">24298541</pub-id></mixed-citation></ref><ref id="pone.0132552.ref069"><label>69</label><mixed-citation publication-type="journal"><name><surname>Neumann</surname><given-names>JK</given-names></name>, <name><surname>McCarty</surname><given-names>GA</given-names></name>. <article-title>Behavioral approaches to reduce hypersensitive gag response</article-title>. <source>J Prosthet Dent</source><year>2001</year>; <volume>85</volume>: <fpage>305</fpage>–<lpage>305</lpage>. <pub-id pub-id-type="pmid">11264940</pub-id></mixed-citation></ref><ref id="pone.0132552.ref070"><label>70</label><mixed-citation publication-type="journal"><name><surname>Liebenberg</surname><given-names>WH</given-names></name>. <article-title>Removable partial denture abutment restoration: a case report illustrating a new direct technique</article-title>. <source>Quintessence Int</source><year>1995</year>; <volume>26</volume>: <fpage>175</fpage>–<lpage>9</lpage>. <pub-id pub-id-type="pmid">7568732</pub-id></mixed-citation></ref><ref id="pone.0132552.ref071"><label>71</label><mixed-citation publication-type="journal"><name><surname>Maezawa</surname><given-names>N</given-names></name>, <name><surname>Shiota</surname><given-names>M</given-names></name>, <name><surname>Kasugai</surname><given-names>S</given-names></name>, <name><surname>Wakabayashi</surname><given-names>N</given-names></name>. <article-title>Three-dimensional stress analysis of tooth/impact-retained long-span fixed dentures</article-title>. <source>Int J Oral Maxillofac Implants</source><year>2007</year>; <volume>22</volume>: <fpage>710</fpage>–<lpage>718</lpage>. <pub-id pub-id-type="pmid">17974104</pub-id></mixed-citation></ref></ref-list></back></pmc></record>Pour manipuler ce document sous Unix (Dilib)
EXPLOR_STEP=$WICRI_ROOT/Wicri/Santé/explor/EdenteV2/Data/Pmc/Corpus
HfdSelect -h $EXPLOR_STEP/biblio.hfd -nk 000418 | SxmlIndent | more
Ou
HfdSelect -h $EXPLOR_AREA/Data/Pmc/Corpus/biblio.hfd -nk 000418 | SxmlIndent | more
Pour mettre un lien sur cette page dans le réseau Wicri
{{Explor lien
|wiki= Wicri/Santé
|area= EdenteV2
|flux= Pmc
|étape= Corpus
|type= RBID
|clé=
|texte=
}}
| This area was generated with Dilib version V0.6.32. |  |