In vitro Evaluation of the Relationship between Gray Scales in Digital Intraoral Radiographs and Hounsfield Units in CT Scans
Identifieur interne : 003027 ( Pmc/Corpus ); précédent : 003026; suivant : 003028In vitro Evaluation of the Relationship between Gray Scales in Digital Intraoral Radiographs and Hounsfield Units in CT Scans
Auteurs : L. Khojastepour ; S. Mohammadzadeh ; M. Jazayeri ; M. OmidiSource :
- Journal of Biomedical Physics & Engineering [ 2251-7200 ] ; 2017.
Abstract
Jaw bone quality plays an essential role in treatment planning and prognosis of dental implants. Regarding several available methods for bone density measurements, they are not routinely used before implant surgery due to hard accessibility.
An in vitro investigation of correlation between average gray scale in direct digital radiographs and Hounsfield units in CT-Scan provides a feasible method for evaluating alveolar bone quality prior to implant surgery.
26 sheep’s mandibles in which a square shape ROI marked by gutta percha, were prepared. Three direct digital radiographs (CCD sensor) from every specimen were taken using 80, 100 and 200 milli-seconds. Then, the average gray levels for ROIs were calculated using a costume-made software. Next, the specimens were scanned using a 16-slice spiral CT and the Hounsfield Unit of each ROI was calculated. Pearson analysis measured the correlation between Hounsfield units and average gray levels.
There was a positive correlation between Hounsfield unit and average gray level in the radiographs and the correlation was better in higher exposure times.
It is possible to estimate Hounsfield unit and bone density in the jaw bones using average gray scale in a digital radiograph. This approach is easy, simple and available and also results in lower patient exposure comparing other bone densitometric analysis methods.
Url:
PubMed: 29082220
PubMed Central: 5654135
Links to Exploration step
PMC:5654135Le document en format XML
<record><TEI><teiHeader><fileDesc><titleStmt><title xml:lang="en">In vitro Evaluation of the Relationship between Gray Scales in Digital Intraoral Radiographs and Hounsfield Units in CT Scans
</title><author><name sortKey="Khojastepour, L" sort="Khojastepour, L" uniqKey="Khojastepour L" first="L." last="Khojastepour">L. Khojastepour</name><affiliation><nlm:aff id="aff1">Professor of Oral and Maxillofacial Radiology (M.Sc.), Department of Radiology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran</nlm:aff></affiliation></author><author><name sortKey="Mohammadzadeh, S" sort="Mohammadzadeh, S" uniqKey="Mohammadzadeh S" first="S." last="Mohammadzadeh">S. Mohammadzadeh</name><affiliation><nlm:aff id="aff2">Specialist in Periodontology (M.Sc.), Department of Periodontics, School of Dentistry, Bushehr University of Medical Sciences, Bushehr, Iran</nlm:aff></affiliation></author><author><name sortKey="Jazayeri, M" sort="Jazayeri, M" uniqKey="Jazayeri M" first="M." last="Jazayeri">M. Jazayeri</name><affiliation><nlm:aff id="aff3">Specialist in Oral and Maxillofacial Radiology (M.Sc.), Private Clinic of Oral and Maxillofacial Radiology, Khoramabad, Iran</nlm:aff></affiliation></author><author><name sortKey="Omidi, M" sort="Omidi, M" uniqKey="Omidi M" first="M." last="Omidi">M. Omidi</name><affiliation><nlm:aff>NONE</nlm:aff></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">PMC</idno><idno type="pmid">29082220</idno><idno type="pmc">5654135</idno><idno type="url">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5654135</idno><idno type="RBID">PMC:5654135</idno><date when="2017">2017</date><idno type="wicri:Area/Pmc/Corpus">003027</idno><idno type="wicri:explorRef" wicri:stream="Pmc" wicri:step="Corpus" wicri:corpus="PMC">003027</idno></publicationStmt><sourceDesc><biblStruct><analytic><title xml:lang="en" level="a" type="main">In vitro Evaluation of the Relationship between Gray Scales in Digital Intraoral Radiographs and Hounsfield Units in CT Scans
</title><author><name sortKey="Khojastepour, L" sort="Khojastepour, L" uniqKey="Khojastepour L" first="L." last="Khojastepour">L. Khojastepour</name><affiliation><nlm:aff id="aff1">Professor of Oral and Maxillofacial Radiology (M.Sc.), Department of Radiology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran</nlm:aff></affiliation></author><author><name sortKey="Mohammadzadeh, S" sort="Mohammadzadeh, S" uniqKey="Mohammadzadeh S" first="S." last="Mohammadzadeh">S. Mohammadzadeh</name><affiliation><nlm:aff id="aff2">Specialist in Periodontology (M.Sc.), Department of Periodontics, School of Dentistry, Bushehr University of Medical Sciences, Bushehr, Iran</nlm:aff></affiliation></author><author><name sortKey="Jazayeri, M" sort="Jazayeri, M" uniqKey="Jazayeri M" first="M." last="Jazayeri">M. Jazayeri</name><affiliation><nlm:aff id="aff3">Specialist in Oral and Maxillofacial Radiology (M.Sc.), Private Clinic of Oral and Maxillofacial Radiology, Khoramabad, Iran</nlm:aff></affiliation></author><author><name sortKey="Omidi, M" sort="Omidi, M" uniqKey="Omidi M" first="M." last="Omidi">M. Omidi</name><affiliation><nlm:aff>NONE</nlm:aff></affiliation></author></analytic><series><title level="j">Journal of Biomedical Physics & Engineering</title><idno type="eISSN">2251-7200</idno><imprint><date when="2017">2017</date></imprint></series></biblStruct></sourceDesc></fileDesc><profileDesc><textClass></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en"><sec id="st1"><title>Background:</title><p>Jaw bone quality plays an essential role in treatment planning and prognosis of dental implants. Regarding several available methods for bone density measurements, they are not routinely used before implant surgery due to hard accessibility.
</p></sec><sec id="st2"><title>Objective: </title><p>An in vitro investigation of correlation between average gray scale in direct digital radiographs and Hounsfield units in CT-Scan provides a feasible method for evaluating alveolar bone quality prior to implant surgery.
</p></sec><sec id="st3"><title>Methods: </title><p>26 sheep’s mandibles in which a square shape ROI marked by gutta percha, were prepared. Three direct digital radiographs (CCD sensor) from every specimen were taken using 80, 100 and 200 milli-seconds. Then, the average gray levels for ROIs were calculated using a costume-made software. Next, the specimens were scanned using a 16-slice spiral CT and the Hounsfield Unit of each ROI was calculated. Pearson analysis measured the correlation between Hounsfield units and average gray levels.
</p></sec><sec id="st4"><title>Results:</title><p>There was a positive correlation between Hounsfield unit and average gray level in the radiographs and the correlation was better in higher exposure times.
</p></sec><sec id="st5"><title>Conclusion:</title><p>It is possible to estimate Hounsfield unit and bone density in the jaw bones using average gray scale in a digital radiograph. This approach is easy, simple and available and also results in lower patient exposure comparing other bone densitometric analysis methods.
</p></sec></div></front><back><div1 type="bibliography"><listBibl><biblStruct><analytic><author><name sortKey="Compston, J" uniqKey="Compston J">J Compston</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Fyhrie, Dp" uniqKey="Fyhrie D">DP Fyhrie</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Licata, A" uniqKey="Licata A">A Licata</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sievanen, H" uniqKey="Sievanen H">H Sievanen</name></author><author><name sortKey="Kannus, P" uniqKey="Kannus P">P Kannus</name></author><author><name sortKey="Jarvinen, Tl" uniqKey="Jarvinen T">TL Jarvinen</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Minkin, C" uniqKey="Minkin C">C Minkin</name></author><author><name sortKey="Marinho, Vc" uniqKey="Marinho V">VC Marinho</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sakka, S" uniqKey="Sakka S">S Sakka</name></author><author><name sortKey="Coulthard, P" uniqKey="Coulthard P">P Coulthard</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Santiago, Rc" uniqKey="Santiago R">RC Santiago</name></author><author><name sortKey="De Paula, Fo" uniqKey="De Paula F">FO de Paula</name></author><author><name sortKey="Fraga, Mr" uniqKey="Fraga M">MR Fraga</name></author><author><name sortKey="Picorelli Assis, Nm" uniqKey="Picorelli Assis N">NM Picorelli Assis</name></author><author><name sortKey="Vitral, Rw" uniqKey="Vitral R">RW Vitral</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Misch, Ce" uniqKey="Misch C">CE Misch</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Johansson, P" uniqKey="Johansson P">P Johansson</name></author><author><name sortKey="Strid, K" uniqKey="Strid K">K Strid</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Scarfe, Wc" uniqKey="Scarfe W">WC Scarfe</name></author><author><name sortKey="Farman, Ag" uniqKey="Farman A">AG Farman</name></author><author><name sortKey="Sukovic, P" uniqKey="Sukovic P">P Sukovic</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Nackaerts, O" uniqKey="Nackaerts O">O Nackaerts</name></author><author><name sortKey="Maes, F" uniqKey="Maes F">F Maes</name></author><author><name sortKey="Yan, H" uniqKey="Yan H">H Yan</name></author><author><name sortKey="Couto Souza, P" uniqKey="Couto Souza P">P Couto Souza</name></author><author><name sortKey="Pauwels, R" uniqKey="Pauwels R">R Pauwels</name></author><author><name sortKey="Jacobs, R" uniqKey="Jacobs R">R Jacobs</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Naitoh, M" uniqKey="Naitoh M">M Naitoh</name></author><author><name sortKey="Aimiya, H" uniqKey="Aimiya H">H Aimiya</name></author><author><name sortKey="Hirukawa, A" uniqKey="Hirukawa A">A Hirukawa</name></author><author><name sortKey="Ariji, E" uniqKey="Ariji E">E Ariji</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Merheb, J" uniqKey="Merheb J">J Merheb</name></author><author><name sortKey="Van Assche, N" uniqKey="Van Assche N">N Van Assche</name></author><author><name sortKey="Coucke, W" uniqKey="Coucke W">W Coucke</name></author><author><name sortKey="Jacobs, R" uniqKey="Jacobs R">R Jacobs</name></author><author><name sortKey="Naert, I" uniqKey="Naert I">I Naert</name></author><author><name sortKey="Quirynen, M" uniqKey="Quirynen M">M Quirynen</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Gomes, Pp" uniqKey="Gomes P">PP Gomes</name></author><author><name sortKey="Guimaraes Filho, R" uniqKey="Guimaraes Filho R">R Guimaraes Filho</name></author><author><name sortKey="Mazzonetto, R" uniqKey="Mazzonetto R">R Mazzonetto</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Trisi, P" uniqKey="Trisi P">P Trisi</name></author><author><name sortKey="Todisco, M" uniqKey="Todisco M">M Todisco</name></author><author><name sortKey="Consolo, U" uniqKey="Consolo U">U Consolo</name></author><author><name sortKey="Travaglini, D" uniqKey="Travaglini D">D Travaglini</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kayipmaz, S" uniqKey="Kayipmaz S">S Kayipmaz</name></author><author><name sortKey="Sezgin, Os" uniqKey="Sezgin O">OS Sezgin</name></author><author><name sortKey="Saricaoglu, St" uniqKey="Saricaoglu S">ST Saricaoglu</name></author><author><name sortKey="Can, G" uniqKey="Can G">G Can</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Ulusu, T" uniqKey="Ulusu T">T Ulusu</name></author><author><name sortKey="Bodur, H" uniqKey="Bodur H">H Bodur</name></author><author><name sortKey="Odabas, Me" uniqKey="Odabas M">ME Odabas</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kamburoglu, K" uniqKey="Kamburoglu K">K Kamburoglu</name></author><author><name sortKey="Senel, B" uniqKey="Senel B">B Senel</name></author><author><name sortKey="Yuksel, Sp" uniqKey="Yuksel S">SP Yuksel</name></author><author><name sortKey="Ozen, T" uniqKey="Ozen T">T Ozen</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Senel, B" uniqKey="Senel B">B Senel</name></author><author><name sortKey="Kamburoglu, K" uniqKey="Kamburoglu K">K Kamburoglu</name></author><author><name sortKey="Ucok, O" uniqKey="Ucok O">O Ucok</name></author><author><name sortKey="Yuksel, Sp" uniqKey="Yuksel S">SP Yuksel</name></author><author><name sortKey="Ozen, T" uniqKey="Ozen T">T Ozen</name></author><author><name sortKey="Avsever, H" uniqKey="Avsever H">H Avsever</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Schropp, L" uniqKey="Schropp L">L Schropp</name></author><author><name sortKey="Alyass, Ns" uniqKey="Alyass N">NS Alyass</name></author><author><name sortKey="Wenzel, A" uniqKey="Wenzel A">A Wenzel</name></author><author><name sortKey="Stavropoulos, A" uniqKey="Stavropoulos A">A Stavropoulos</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Turkyilmaz, I" uniqKey="Turkyilmaz I">I Turkyilmaz</name></author><author><name sortKey="Mcglumphy, Ea" uniqKey="Mcglumphy E">EA McGlumphy</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Morea, C" uniqKey="Morea C">C Morea</name></author><author><name sortKey="Dominguez, Gc" uniqKey="Dominguez G">GC Dominguez</name></author><author><name sortKey="Coutinho, A" uniqKey="Coutinho A">A Coutinho</name></author><author><name sortKey="Chilvarquer, I" uniqKey="Chilvarquer I">I Chilvarquer</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Gu, L" uniqKey="Gu L">L Gu</name></author><author><name sortKey="Yu, Ly" uniqKey="Yu L">LY Yu</name></author><author><name sortKey="Zhou, Y" uniqKey="Zhou Y">Y Zhou</name></author><author><name sortKey="Xie, C" uniqKey="Xie C">C Xie</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Norton, Mr" uniqKey="Norton M">MR Norton</name></author><author><name sortKey="Gamble, C" uniqKey="Gamble C">C Gamble</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Shapurian, T" uniqKey="Shapurian T">T Shapurian</name></author><author><name sortKey="Damoulis, Pd" uniqKey="Damoulis P">PD Damoulis</name></author><author><name sortKey="Reiser, Gm" uniqKey="Reiser G">GM Reiser</name></author><author><name sortKey="Griffin, Tj" uniqKey="Griffin T">TJ Griffin</name></author><author><name sortKey="Rand, Wm" uniqKey="Rand W">WM Rand</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Mah, P" uniqKey="Mah P">P Mah</name></author><author><name sortKey="Reeves, Te" uniqKey="Reeves T">TE Reeves</name></author><author><name sortKey="Mcdavid, Wd" uniqKey="Mcdavid W">WD McDavid</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Nomura, Y" uniqKey="Nomura Y">Y Nomura</name></author><author><name sortKey="Watanabe, H" uniqKey="Watanabe H">H Watanabe</name></author><author><name sortKey="Honda, E" uniqKey="Honda E">E Honda</name></author><author><name sortKey="Kurabayashi, T" uniqKey="Kurabayashi T">T Kurabayashi</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Miles, Da" uniqKey="Miles D">DA Miles</name></author><author><name sortKey="Danforth, Ra" uniqKey="Danforth R">RA Danforth</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Nackaerts, O" uniqKey="Nackaerts O">O Nackaerts</name></author><author><name sortKey="Jacobs, R" uniqKey="Jacobs R">R Jacobs</name></author><author><name sortKey="Horner, K" uniqKey="Horner K">K Horner</name></author><author><name sortKey="Zhao, F" uniqKey="Zhao F">F Zhao</name></author><author><name sortKey="Lindh, C" uniqKey="Lindh C">C Lindh</name></author><author><name sortKey="Karayianni, K" uniqKey="Karayianni K">K Karayianni</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sakakura, Ce" uniqKey="Sakakura C">CE Sakakura</name></author><author><name sortKey="Giro, G" uniqKey="Giro G">G Giro</name></author><author><name sortKey="Goncalves, D" uniqKey="Goncalves D">D Goncalves</name></author><author><name sortKey="Pereira, Rm" uniqKey="Pereira R">RM Pereira</name></author><author><name sortKey="Orrico, Sr" uniqKey="Orrico S">SR Orrico</name></author><author><name sortKey="Marcantonio, E Jr" uniqKey="Marcantonio E">E Jr Marcantonio</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">J Biomed Phys Eng</journal-id><journal-id journal-id-type="iso-abbrev">J Biomed Phys Eng</journal-id><journal-title-group><journal-title>Journal of Biomedical Physics & Engineering</journal-title></journal-title-group><issn pub-type="epub">2251-7200</issn><publisher><publisher-name>Journal of Biomedical Physics and Engineering</publisher-name><publisher-loc>Iran</publisher-loc></publisher></journal-meta><article-meta><article-id pub-id-type="pmid">29082220</article-id><article-id pub-id-type="pmc">5654135</article-id><article-id pub-id-type="publisher-id">JBPE-7-3</article-id><article-categories><subj-group subj-group-type="heading"><subject>Original Article</subject></subj-group></article-categories><title-group><article-title>In vitro Evaluation of the Relationship between Gray Scales in Digital Intraoral Radiographs and Hounsfield Units in CT Scans
</article-title></title-group><contrib-group><contrib contrib-type="author"><name><surname>Khojastepour</surname><given-names>L.</given-names></name><xref ref-type="aff" rid="aff1">1</xref></contrib><contrib contrib-type="author"><name><surname>Mohammadzadeh</surname><given-names>S.</given-names></name><xref ref-type="aff" rid="aff2">2</xref></contrib><contrib contrib-type="author"><name><surname>Jazayeri</surname><given-names>M.</given-names></name><xref ref-type="aff" rid="aff3">3</xref></contrib><contrib contrib-type="author"><name><surname>Omidi</surname><given-names>M.</given-names></name><xref ref-type="aff" rid="aff4">4*</xref></contrib></contrib-group><aff id="aff1"><label>1</label>Professor of Oral and Maxillofacial Radiology (M.Sc.), Department of Radiology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran</aff><aff id="aff2"><label>2</label>Specialist in Periodontology (M.Sc.), Department of Periodontics, School of Dentistry, Bushehr University of Medical Sciences, Bushehr, Iran</aff><aff id="aff3"><label>3</label>Specialist in Oral and Maxillofacial Radiology (M.Sc.), Private Clinic of Oral and Maxillofacial Radiology, Khoramabad, Iran</aff><aff id="aff4"><label>4</label>Assistant Professor of Oral and Maxillofacial Radiology (M.Sc), Department of Radiology, School of Dentistry, Shiraz University of Medical Sciences, International Branch, Shiraz, Iran</aff><author-notes><corresp id="cor1"><bold>*Corresponding author:</bold>M. Omidi,
Assistant Professor of Oral and Maxillofacial Radiology (M.Sc), Department of Radiology, School of Dentistry, Shiraz University of Medical Sciences, International Branch, Shiraz, Iran
</corresp><corresp id="cor2">E-mail : <email>mahsaomidi@yahoo.com</email></corresp></author-notes><pub-date pub-type="collection"><month>9</month><year>2017</year></pub-date><pub-date pub-type="epub"><day>01</day><month>9</month><year>2017</year></pub-date><volume>7</volume><issue>3</issue><fpage>289</fpage><lpage>298</lpage><history><date date-type="accepted"><day>7</day><month>9</month><year>2015</year></date><date date-type="received"><day>12</day><month>8</month><year>2015</year></date></history><permissions><copyright-statement>Copyright: © Journal of Biomedical Physics and Engineering</copyright-statement><license license-type="open-access" xlink:href="http://creativecommons.org/licenses/by-nc-sa/3.0"><license-p>This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</license-p></license></permissions><abstract><sec id="st1"><title>Background:</title><p>Jaw bone quality plays an essential role in treatment planning and prognosis of dental implants. Regarding several available methods for bone density measurements, they are not routinely used before implant surgery due to hard accessibility.
</p></sec><sec id="st2"><title>Objective: </title><p>An in vitro investigation of correlation between average gray scale in direct digital radiographs and Hounsfield units in CT-Scan provides a feasible method for evaluating alveolar bone quality prior to implant surgery.
</p></sec><sec id="st3"><title>Methods: </title><p>26 sheep’s mandibles in which a square shape ROI marked by gutta percha, were prepared. Three direct digital radiographs (CCD sensor) from every specimen were taken using 80, 100 and 200 milli-seconds. Then, the average gray levels for ROIs were calculated using a costume-made software. Next, the specimens were scanned using a 16-slice spiral CT and the Hounsfield Unit of each ROI was calculated. Pearson analysis measured the correlation between Hounsfield units and average gray levels.
</p></sec><sec id="st4"><title>Results:</title><p>There was a positive correlation between Hounsfield unit and average gray level in the radiographs and the correlation was better in higher exposure times.
</p></sec><sec id="st5"><title>Conclusion:</title><p>It is possible to estimate Hounsfield unit and bone density in the jaw bones using average gray scale in a digital radiograph. This approach is easy, simple and available and also results in lower patient exposure comparing other bone densitometric analysis methods.
</p></sec></abstract><kwd-group><kwd>Hounsfield Units </kwd><kwd> Gray Level </kwd><kwd> Bone Density </kwd><kwd> Implant</kwd></kwd-group></article-meta></front><body><sec sec-type="Introduction" id="sec1-1"><title>Introduction</title><p>The term “bone quality” has been extensively used in the literature to describe different aspects of bone characteristics with variable definitions depending on the context.
Among inseparable factors which influence bone quality is the trabecular bone [<xref rid="ref1" ref-type="bibr">1</xref>-<xref rid="ref4" ref-type="bibr">4</xref>]. The trabecular bone
is the primary anatomical and functional unit of cancellous bone. Cortical bone helps attain primary implant stability. The role of cancellous bone, however, is also significant as cancellous
bone has a higher bone turnover rate than cortical bone [<xref rid="ref5" ref-type="bibr">5</xref>]. Besides, a dental implant is mainly in contact with cancellous part of the bone [<xref rid="ref6" ref-type="bibr">6</xref>].
Accordingly, osseointegration process and healing at the implant bone surface is influenced by cancellous bone [<xref rid="ref5" ref-type="bibr">5</xref>]. </p><p>Knowledge of bone density in various areas of maxilla and mandible might help a clinician to understand and correlate observed clinical phenomenon. A close relationship exists between bone density
and anchorage potential as well as the rate of tooth movement in orthodontic [<xref rid="ref6" ref-type="bibr">6</xref>,<xref rid="ref7" ref-type="bibr">7</xref>]. </p><p>The studies reveal that high percentage of dentists merely use panoramic images for planning implant treatment and less than 10% take advantage of CT. However, American Academy of Oral and Maxillofacial Radiology has made it an instruction to use a 3D imaging such as CT in order to examine implant location [<xref rid="ref8" ref-type="bibr">8</xref>]. </p><p>The practical and substantial assessment of bone quality often depends on subjective procedures. These usually include the tactile impression while drilling to prepare the implant site and visual evaluation of CT and topographic images. There are some methods that are able to objectively assess bone quality for example cutting resistance analysis (CRA) which measures clinical bone torque threshold where bone implant contact is destroyed. The major limitation of CRA is that it does not give any information on bone quality until osteotomy site is prepared [<xref rid="ref9" ref-type="bibr">9</xref>]. </p><p>Recently, the use of cone-beam (CBCT) in dentistry has increased, because CBCT is associated with benefits such as increased patient comfort, lower radiation doses and lower operation costs compared to conventional CT [<xref rid="ref10" ref-type="bibr">10</xref>]. However, Nackaerts et al. [<xref rid="ref11" ref-type="bibr">11</xref>] demonstrated that density profiles of conventional CT showed stable HU values, whereas intensity values in CBCT images are not reliable because the values are influenced by the device used, imaging parameters and positioning. Accordingly, Naitoh et al. [<xref rid="ref12" ref-type="bibr">12</xref>] found that the trabecular bone volume per total tissue volume obtained using CBCT images was closely correlated with HU values generated from conventional CT images.
</p><p>Beam attenuation coefficient can be determined on a CT image. Measured quantities are represented by Hounsfield units (HU) which are also called CT numbers. HU also ranges from -1000 (air) to +3000 (enamel), each corresponding to different levels of beam attenuation [<xref rid="ref8" ref-type="bibr">8</xref>]. </p><p>Misch has classified bone density under 4 categories of D1, D2, D3 and D4 in edentulous maxillary and mandibular areas. D1 is compact cortical bone. D2 is attributed to nonporous compact cortical bone on the crest and body of bone including large trabecular bone. D3 consists of thinner porous cortical crest and a fine trabecular bone near implant. Most often, no cortical bone can be found in the crest for the density of D4 and fine trabecular bone forms nearly all the size of the bone next to the implant (<xref ref-type="table" rid="T1">Table 1</xref>). Bone density may be determined by touching the area through surgery based on edentulous situation or radiographic evaluation [<xref rid="ref8" ref-type="bibr">8</xref>]. </p><table-wrap id="T1" position="float"><label>Table 1</label><caption><p>Bone density classification and Hounsfield number</p></caption><table frame="hsides" rules="groups" width="100%"><thead><tr><th style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #650000 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">Bone Density at CT Image</th><th style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #650000 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">Misch’s Classification</th></tr></thead><tbody><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">Hounsfield Number >1250</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">D1</td></tr><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">850-1250</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">D2</td></tr><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">350-850</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">D3</td></tr><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">150-350</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">D4</td></tr><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">Hounsfield Number < 150</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">D5</td></tr></tbody></table></table-wrap><p>Panoramic or periapical radiography cannot be used to determine bone density, because lateral cortical plates will make the density of trabecular bone an ambiguous criterion. Moreover, minor changes from D2 to D3 cannot be evaluated by such modes of radiography. Therefore, initial treatment plans usually begin with such modes of radiography and are followed by density evaluation method on the implant location. Bone density range can be more accurately determined by tomography methods of radiography, especially CT.
</p><p>Generally speaking, the higher the CT number, the more compact the tissue. There are software utilities that are able to place the implant on CT image electronically and then, Hounsfield number would evaluate implant location [<xref rid="ref8" ref-type="bibr">8</xref>]. </p><p>Merheb et al. [<xref rid="ref13" ref-type="bibr">13</xref>] showed that a significant linear relationship existed between damping values and HU values at implant insertion and suggested that preoperative evaluation of cortical thickness and trabecular bone HU appeared to be the most reliable method for predicting implant stability.
</p><p>In the present study, we tried to examine the animal samples by CT-Scan, as the most accurate and repeatable diagnostic method for bone density testing, and to study digital images of samples in order to investigate the relationship between these two measurement methods and also to translate the Hounsfield unit measured by CT-Scan into Gray Scale code. Clearly, the priority for this study was not to suggest a very accurate method of bone density testing but to offer a simple, inexpensive, fast, available and applicable method with an acceptable precision to be used at clinic.
</p></sec><sec sec-type="Material and Methods" id="sec1-2"><title>Material and Methods</title><p>This research was carried out on 26 samples of mandibles of sheep. All soft tissues were removed from the mandible. Gutta-percha cones were used to form a square window (1×1cm) on buccal
surface to enable precise selection of the areas on each sample (<xref ref-type="fig" rid="JBPE-7-289-g001.tif">Figure 1</xref>). The samples were put into a container of melted wax for covering all the surface of samples with a thin layer of wax. This was done to simulate soft tissue and to avoid direct contact of air with the bone in order to postpone decay. Wax layers were used with various thicknesses within the range of 10-20 mm.
</p><fig id="JBPE-7-289-g001.tif" position="float"><label>Figure1</label><caption><p>Gutta-percha cones were used to form a square window (1×1cm) on buccal surface of mandibles.
</p></caption><graphic xlink:href="JBPE-7-289-g001"></graphic></fig><p>In the first step, the digital radiographs were performed with CCD sensor (size 2; sensor model: SUNY) at tube voltage of 70 KVP, Cone 12 cm, mA=8, Time: 80, 100, 200 milliseconds. The sensor was placed on the lingual surface and the tube was placed on the buccal side of mandible with 10 cm distance to the object. Images were recorded in BMP format.
</p><p>In the next step, CT scans were performed using a spiral CT machine (Light Speed Ultra16; General Electric, Milwaukee, WI, USA). Then, one-millimeter slices were prepared. The scanner was calibrated a day before it was used for the first sample according to manufacturer’s guidelines.
</p><p>For evaluation of radiographic images, the pixels inside the square were read by our developed software for this purpose in MATLAB environment and assigned a number according to the gray scale level. Finally, the average gray level was calculated for the square. The assessment calculates the attenuation by the buccal, lingual cortices, cancellous bone and wax layer, altogether. Results were recorded for three times of 80, 100 and 200 milliseconds.
</p><p>HU was measured in two different methods. (A) One method was to measure HU in three different slices at 2mm intervals (<xref ref-type="fig" rid="JBPE-7-289-g002.tif">Figure 2</xref>); B) the other way was to estimate HU on one slice in the middle of the selected area and to consider it as mean HU (<xref ref-type="fig" rid="JBPE-7-289-g003.tif">Figure 3</xref>). </p><fig id="JBPE-7-289-g002.tif" position="float"><label>Figure2</label><caption><p>Measuring HU in three different slices at 2mm intervals
</p></caption><graphic xlink:href="JBPE-7-289-g002"></graphic></fig><fig id="JBPE-7-289-g003.tif" position="float"><label>Figure3</label><caption><p>Measuring HU in one slice in the middle of the selected area
</p></caption><graphic xlink:href="JBPE-7-289-g003"></graphic></fig><p>In the first analysis (A) which included the mean average of three spots, the squares (formed by gutta-percha cones) were analyzed for every sample and the average gray scale was calculated. Therefore, the impacts of the buccal and lingual cortical plates as well as the cancellous area are considered in the calculation of HU. Then, Pearson’s correlation test was applied to analyze the data.
</p><p>Coronal cross sections were used for the estimation of HU (<xref ref-type="fig" rid="JBPE-7-289-g004.tif">Figure 4</xref>). In the next step, only one slice is selected from the middle of the square, instead of 3 cross-sectional slices, and the calculated HU was recorded. Afterwards, Pearson’s Correlation Coefficient was calculated for the new data.
</p><fig id="JBPE-7-289-g004.tif" position="float"><label>Figure4</label><caption><p>A spot is allotted to coronal plate (which was selected earlier on the lateral view) and then CT software gives the HU for this spot.
</p></caption><graphic xlink:href="JBPE-7-289-g004"></graphic></fig></sec><sec sec-type="Results" id="sec1-3"><title>Results</title><p>The correlation coefficients between HU and Average Gray Level obtained via various measurements is listed in <xref ref-type="table" rid="T2">Table 2</xref>. </p><table-wrap id="T2" position="float"><label>Table 2</label><caption><p>Correlation coefficients between HU & Average Gray Level obtained via various measurements</p></caption><table frame="hsides" rules="groups" width="100%"><thead><tr><th style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #650000 1.0pt;" align="left" colspan="1" rowspan="1" valign="top"></th><th style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #650000 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">Pearson correlation between HU & Average Gray Level</th></tr></thead><tbody><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">26 selected areas (average mean of 3 slices); 80 milliseconds (A)</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">0.577 <xref ref-type="table-fn" rid="t2f1">*</xref></td></tr><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">26 selected areas (average mean of 3 slices); 100 milliseconds (A)</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">0.656 <xref ref-type="table-fn" rid="t2f2">**</xref></td></tr><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">26 selected areas (average mean of 3 slices); 200 milliseconds (A)</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">0.695 <xref ref-type="table-fn" rid="t2f2">**</xref></td></tr><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">26 selected areas (1 slice); 80 milliseconds (B)</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">0.660 <xref ref-type="table-fn" rid="t2f2">**</xref></td></tr><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">26 selected areas (1 slice); 100 milliseconds (B)</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">0.759 <xref ref-type="table-fn" rid="t2f2">**</xref></td></tr><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">26 selected areas (1 slice); 200 milliseconds (B)</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">0.777 <xref ref-type="table-fn" rid="t2f2">**</xref></td></tr><tr><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">Correlation Coefficient between two methods of HU calculation</td><td style="color:#000000;border-top:none;border-left:none;border-right:none 1.0pt;border-bottom:solid #A30F63 1.0pt;" align="left" colspan="1" rowspan="1" valign="top">0.949 <xref ref-type="table-fn" rid="t2f2">**</xref></td></tr></tbody></table><table-wrap-foot><fn id="t2f1"><label>*</label><p>Correlation is significant at the 0.05 level (2-tailed)
</p></fn><fn id="t2f2"><label>**</label><p>Correlation is significant at the 0.01 level (2-tailed)
</p></fn></table-wrap-foot></table-wrap><p>Pearson’s statistical test revealed that there was a positive correlation between HU and Average Gray Scale in all cases and as it can be observed in <xref ref-type="table" rid="T2">Table 2</xref>, the correlation increases when radiation time increases.
</p></sec><sec sec-type="Discussion" id="sec1-4"><title>Discussion</title><p>Since available human samples were not sufficient to carry out this study and regarding ethical concerns, we decided to use sheep mandible as a holding media for performing CT. The sheep mandible is similar to human mandible in format size and structure and unavailability of sufficient human mandible, the mandible of sheep has been used in several in-vitro experiments on osteotomies and rigid internal fixation as well as dental implantology [<xref rid="ref14" ref-type="bibr">14</xref>,<xref rid="ref15" ref-type="bibr">15</xref>]. </p><p>We used wax on surface of the bone because a wax layer attenuates X-Ray to some extent, just like soft tissue. Dental wax [<xref rid="ref16" ref-type="bibr">16</xref>,<xref rid="ref17" ref-type="bibr">17</xref>] and different acrylic [<xref rid="ref18" ref-type="bibr">18</xref>,<xref rid="ref19" ref-type="bibr">19</xref>] are among the most frequent materials which have been used for simulating soft tissues during in- vitro studies. Recently, Schropp et al. examined the validity of wax and acrylic resin as soft-tissue simulation. They concluded that for in vitro radiographic studies, the radiographic density of average human cheek could be simulated by 13-17 mm thickness of dental wax or 14.5 mm thickness of acrylic resin [<xref rid="ref20" ref-type="bibr">20</xref>]. </p><p>We used Coronal cross section for the estimation of HU because the mandibular buccal and lingual cortical plates as well as interstitial cancellous space can affect separately in the calculation of HU. Turkyilmaz et al. [<xref rid="ref21" ref-type="bibr">21</xref>] used this method (investigation of HU in coronal views) to calculate HU in order to study the spots between HU and the highest torque as well as frequency augmentation.
</p><p>The increase of correlation coefficient has a linear correlation with the increase of radiation time since, as the radiation time increases, the effect of soft tissue on the image decreases. Hence, the graphic data are mostly indicative of hard tissue situation.
</p><p>Other factors affecting the correlation between the data are KVP and the distance between x-ray tube and the sample.
</p><p>Kvp and its effects have not been addressed in this study because of its complexity as well as time limitation; however, RVG machine used in this study also suffered from the limitation in selecting Kvp. Clearly, the higher the Kvp is (but within the acceptable range in dentistry), the higher its penetration power will be, and the lesser amount of its energy will be absorbed by the soft tissue. Consequently, the increase of kVp will probably result in increased relationship between gray level and HU.
</p><p>The factor of distance should also be investigated as the distance between the X-ray source and the object because as the changes are trivial (about 2 cm as compared to 30-40 cm), its effect can be negligible based on the inverse-square law. However, the absence of a significant correlation between Gray Scale and HU might be attributed to the changes in this factor.
</p><p>As the X-ray scatters and the image gets more opaque, the soft tissue inevitably affects the results and this, in turn, reduces the correlation among the data. The researchers are suggested to increase kVp in the future studies in order to reduce the influence of soft tissue.
</p><p>To the best of authors’ knowledge, no exact similar studies have been conducted to analyze the relationship between HU in CT and Gray Scale in direct digital radiography; however, some studies resemble ours which will be briefly discussed here.
</p><p>Our findings were also in agreement with the findings of Morea et al. (2010). They evaluated quantitative variations of in-vitro mineral density by varying the exposure time of direct digital radiographs using a computer-assisted densitometric image analysis (CADIA) program. They suggested that as radiation time increased, CADIA calculated more accurate results; however, the radiation time should not be increased too much (more than relative film latitude), because the data would be lost [<xref rid="ref22" ref-type="bibr">22</xref>]. </p><p>GUL et al. [<xref rid="ref23" ref-type="bibr">23</xref>] (2008) investigated the relationship between optical density in Panoramic scanning images and HU of the same areas in CT scan. They suggested a linear relationship between these two measurement methods which is in agreement with the results yielded by the current study.
</p><p>Norton and Gamble (2001) proposed an image-based bone density classification that used grey-scale values (HU) from CT. They demonstrated that an objective scale of bone density based on the Houndsfield scale, could be established and there was a strong correlation between bone density value and subjective quality score as well as between the bone density score and the region of the mouth. They reported the mean bone density from CT was 682 HU for 139 sites. They recorded the mean bone densities in the anterior mandible, the posterior mandible, the anterior maxilla, the posterior maxilla were 970, 669, 696 and 417 HU, respectively [<xref rid="ref24" ref-type="bibr">24</xref>]. </p><p> Shapurian et al. (2006) reported that the average bone density values in the anterior mandible, the anterior maxilla, the posterior maxilla, the posterior mandible were 559, 517, 333 and 321 HU for 219 implant sites, respectively [<xref rid="ref25" ref-type="bibr">25</xref>]. Since the Hounsfield scale varies according to the scanner used, the determination of HU is not helpful for pre-operative evaluation of bone density.
</p><p>Mah et al. (2008) carried out an in-vitro study to investigate the relationship between Gray Scale in CBCT and HU and the results showed that the method could be a simple method for estimating HU through Gray Scale obtained by CBCT [<xref rid="ref26" ref-type="bibr">26</xref>]. A study conducted by Nomura et al. (2010) revealed that there was a high correlation between the voxel values of CBCT and the CT numbers of multi-slice CT [<xref rid="ref27" ref-type="bibr">27</xref>]. </p><p>Miles and Danforth concluded that CBCT grey levels were inaccurate to rely upon for decisions on implant placement. The values assigned to the voxels (volume elements) are relative HU and cannot be used precisely to estimate bone density [<xref rid="ref28" ref-type="bibr">28</xref>]. </p><p>Nackaerts et al. demonstrated that density profiles of conventional CT showed stable HU values whereas intensity values in CBCT images are not reliable because the values are influenced by the device used, imaging parameters and positioning [<xref rid="ref29" ref-type="bibr">29</xref>]. So, it seems that HU of CT images are more reliable than CBCT.
</p><p>Sakakura et al. (2006) took advantage of Direct Digital Imaging and Gray Scale analysis by software. These results also verify Gray Scale estimation and its application for estimating bone quality; however, standardization or application of a more accurate method for establishing the relationship of Gray Scale numbers has not been used [<xref rid="ref30" ref-type="bibr">30</xref>]. </p></sec><sec sec-type="Conclusion" id="sec1-5"><title>Conclusion</title><p>The findings reveal that HU or bone density of the mandible can be approximately estimated through the average gray levels of digital intra-oral radiographs, and as the radiation time increases (to the extent that the data is not lost and the measurement accuracy is not reduced), the correlation and calculation accuracy will increase. Moreover, in spots where there is no completely distinguishable opaque structure other than the trabecula of the cancellous bone (such as edentulous areas), mean Gray Scale measurement can more essentially show bone density or HU of the area.
</p><p>There is a remarkable reduction of X-ray radiation dose in this method compared to other common bone density measurement methods. It is more reasonable for the risk groups whose bone density is diagnosed to be insufficient by this method, to try more accurate tests for evaluating osteoporosis or other systemic diseases.
</p><p>Finally, this method is assessed to be effective, convenient and useful for obtaining a relative and acceptable measurement of bone quality prior to implantation.
</p></sec></body><back><ack><title>Acknowledgement</title><p>The authors would like to thank the Vice-chancellor of Shiraz University of Medical Science for supporting this research (Grant no. 1323). This article is based on a thesis by Dr. Mohammad Jazayeri, under supervision of Dr. Leila Khojastepour.
</p><p><bold>Conflict of Interest:</bold>None.</p></ack><ref-list><title>References</title><ref id="ref1"><label>1</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Compston</surname><given-names>J</given-names></name></person-group><article-title>Bone quality: what is it and how is it measured?</article-title><source><italic> Arquivos Brasileiros de Endocrinologia & Metabologia</italic></source><year> 2006</year><volume>50</volume><fpage>579</fpage><lpage>85</lpage><pub-id pub-id-type="doi">10.1590/S0004-27302006000400003</pub-id><pub-id pub-id-type="pmid">17117283</pub-id></element-citation></ref><ref id="ref2"><label>2</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Fyhrie</surname><given-names>DP</given-names></name></person-group><article-title>Summary--Measuring “bone quality”</article-title><source><italic> J Musculoskelet Neuronal Interact</italic></source><year> 2005</year><volume>5</volume><fpage>318</fpage><lpage>20</lpage><pub-id pub-id-type="pmid">16340121</pub-id></element-citation></ref><ref id="ref3"><label>3</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Licata</surname><given-names>A</given-names></name></person-group><article-title>Bone density vs bone quality: what’s a clinician to do?</article-title><source><italic> Cleve Clin J Med</italic></source><year> 2009</year><volume>76</volume><fpage>331</fpage><lpage>6</lpage><pub-id pub-id-type="doi">10.3949/ccjm.76a.08041</pub-id><pub-id pub-id-type="pmid">19487553</pub-id></element-citation></ref><ref id="ref4"><label>4</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Sievanen</surname><given-names>H</given-names></name><name><surname>Kannus</surname><given-names>P</given-names></name><name><surname>Jarvinen</surname><given-names>TL</given-names></name></person-group><article-title>Bone quality: an empty term</article-title><source><italic> PLoS Med</italic></source><year> 2007</year><volume>4</volume><fpage>e27</fpage><pub-id pub-id-type="doi">10.1371/journal.pmed.0040027</pub-id><pub-id pub-id-type="pmid">17341126</pub-id></element-citation></ref><ref id="ref5"><label>5</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Minkin</surname><given-names>C</given-names></name><name><surname>Marinho</surname><given-names>VC</given-names></name></person-group><article-title>Role of the osteoclast at the bone-implant interface</article-title><source><italic> Adv Dent Res</italic></source><year> 1999</year><volume>13</volume><fpage>49</fpage><lpage>56</lpage><pub-id pub-id-type="doi">10.1177/08959374990130011401</pub-id><pub-id pub-id-type="pmid">11276746</pub-id></element-citation></ref><ref id="ref6"><label>6</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Sakka</surname><given-names>S</given-names></name><name><surname>Coulthard</surname><given-names>P</given-names></name></person-group><article-title>Bone quality: a reality for the process of osseointegration</article-title><source><italic> Implant Dent</italic></source><year> 2009</year><volume>18</volume><issue>6</issue><fpage>480</fpage><lpage>5</lpage><pub-id pub-id-type="doi">10.1097/ID.0b013e3181bb840d</pub-id><pub-id pub-id-type="pmid">20009601</pub-id></element-citation></ref><ref id="ref7"><label>7</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Santiago</surname><given-names>RC</given-names></name><name><surname>de Paula</surname><given-names>FO</given-names></name><name><surname>Fraga</surname><given-names>MR</given-names></name><name><surname>Picorelli Assis</surname><given-names>NM</given-names></name><name><surname>Vitral</surname><given-names>RW</given-names></name></person-group><article-title>Correlation between miniscrew stability and bone mineral density in orthodontic patients</article-title><source><italic> Am J Orthod Dentofacial Orthop</italic></source><year> 2009</year><volume>136</volume><fpage>243</fpage><lpage>50</lpage><pub-id pub-id-type="doi">10.1016/j.ajodo.2007.08.031</pub-id><pub-id pub-id-type="pmid">19651355</pub-id></element-citation></ref><ref id="ref8"><label>8</label><element-citation publication-type="book"><person-group person-group-type="author"><name><surname>Misch</surname><given-names>CE</given-names></name></person-group><source>Bone density: a key determinant for treatment planning. Contemporary implant dentistry</source><year>2007</year><edition>3rd ed</edition><publisher-loc>St Louis</publisher-loc><publisher-name> Mosby</publisher-name><fpage>130</fpage><lpage>146</lpage></element-citation></ref><ref id="ref9"><label>9</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Johansson</surname><given-names>P</given-names></name><name><surname>Strid</surname><given-names>K</given-names></name></person-group><article-title>Assessment of bone quality from cutting resistance during implant surgery</article-title><source><italic> International Journal of Oral and Maxillofacial Implants</italic></source><year> 1994</year><volume>9</volume><fpage>279</fpage><lpage>88</lpage></element-citation></ref><ref id="ref10"><label>10</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Scarfe</surname><given-names>WC</given-names></name><name><surname>Farman</surname><given-names>AG</given-names></name><name><surname>Sukovic</surname><given-names>P</given-names></name></person-group><article-title>Clinical applications of cone-beam computed tomography in dental practice</article-title><source><italic> J Can Dent Assoc</italic></source><year> 2006</year><volume>72</volume><fpage>75</fpage><lpage>80</lpage><pub-id pub-id-type="pmid">16480609</pub-id></element-citation></ref><ref id="ref11"><label>11</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Nackaerts</surname><given-names>O</given-names></name><name><surname>Maes</surname><given-names>F</given-names></name><name><surname>Yan</surname><given-names>H</given-names></name><name><surname>Couto Souza</surname><given-names>P</given-names></name><name><surname>Pauwels</surname><given-names>R</given-names></name><name><surname>Jacobs</surname><given-names>R</given-names></name></person-group><article-title>Analysis of intensity variability in multislice and cone beam computed tomography</article-title><source><italic> Clin Oral Implants Res</italic></source><year> 2011</year><volume>22</volume><fpage>873</fpage><lpage>9</lpage><pub-id pub-id-type="pmid">21244502</pub-id></element-citation></ref><ref id="ref12"><label>12</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Naitoh</surname><given-names>M</given-names></name><name><surname>Aimiya</surname><given-names>H</given-names></name><name><surname>Hirukawa</surname><given-names>A</given-names></name><name><surname>Ariji</surname><given-names>E</given-names></name></person-group><article-title>Morphometric analysis of mandibular trabecular bone using cone beam computed tomography: an in vitro study</article-title><source><italic> Int J Oral Maxillofac Implants</italic></source><year> 2010</year><volume>25</volume><fpage>1093</fpage><lpage>8</lpage><pub-id pub-id-type="pmid">21197484</pub-id></element-citation></ref><ref id="ref13"><label>13</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Merheb</surname><given-names>J</given-names></name><name><surname>Van Assche</surname><given-names>N</given-names></name><name><surname>Coucke</surname><given-names>W</given-names></name><name><surname>Jacobs</surname><given-names>R</given-names></name><name><surname>Naert</surname><given-names>I</given-names></name><name><surname>Quirynen</surname><given-names>M</given-names></name></person-group><article-title>Relationship between cortical bone thickness or computerized tomography-derived bone density values and implant stability</article-title><source><italic> Clin Oral Implants Res</italic></source><year> 2010</year><volume>21</volume><fpage>612</fpage><lpage>7</lpage><pub-id pub-id-type="doi">10.1111/j.1600-0501.2009.01880.x</pub-id><pub-id pub-id-type="pmid">20666788</pub-id></element-citation></ref><ref id="ref14"><label>14</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Gomes</surname><given-names>PP</given-names></name><name><surname>Guimaraes Filho</surname><given-names>R</given-names></name><name><surname>Mazzonetto</surname><given-names>R</given-names></name></person-group><article-title>Evaluation of the bending strength of rigid internal fixation with absorbable and metallic screws in mandibular ramus sagittal split osteotomy: in vitro study</article-title><source><italic> Pesqui Odontol Bras</italic></source><year> 2003</year><volume>17</volume><fpage>267</fpage><lpage>72</lpage><pub-id pub-id-type="pmid">14762506</pub-id></element-citation></ref><ref id="ref15"><label>15</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Trisi</surname><given-names>P</given-names></name><name><surname>Todisco</surname><given-names>M</given-names></name><name><surname>Consolo</surname><given-names>U</given-names></name><name><surname>Travaglini</surname><given-names>D</given-names></name></person-group><article-title>High versus low implant insertion torque: a histologic, histomorphometric, and biomechanical study in the sheep mandible</article-title><source><italic> Int J Oral Maxillofac Implants</italic></source><year> 2011</year><volume>26</volume><fpage>837</fpage><lpage>49</lpage><pub-id pub-id-type="pmid">21841994</pub-id></element-citation></ref><ref id="ref16"><label>16</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Kayipmaz</surname><given-names>S</given-names></name><name><surname>Sezgin</surname><given-names>OS</given-names></name><name><surname>Saricaoglu</surname><given-names>ST</given-names></name><name><surname>Can</surname><given-names>G</given-names></name></person-group><article-title>An in vitro comparison of diagnostic abilities of conventional radiography, storage phosphor, and cone beam computed tomography to determine occlusal and approximal caries</article-title><source><italic> Eur J Radiol</italic></source><year> 2011</year><volume>80</volume><fpage>478</fpage><lpage>82</lpage><pub-id pub-id-type="doi">10.1016/j.ejrad.2010.09.011</pub-id><pub-id pub-id-type="pmid">20934291</pub-id></element-citation></ref><ref id="ref17"><label>17</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Ulusu</surname><given-names>T</given-names></name><name><surname>Bodur</surname><given-names>H</given-names></name><name><surname>Odabas</surname><given-names>ME</given-names></name></person-group><article-title>In vitro comparison of digital and conventional bitewing radiographs for the detection of approximal caries in primary teeth exposed and viewed by a new wireless handheld unit</article-title><source><italic> Dentomaxillofac Radiol</italic></source><year> 2010</year><volume>39</volume><fpage>91</fpage><lpage>4</lpage><comment>[<ext-link ext-link-type="uri" xlink:href="http://www.ncbi.nlm.nih.gov/pmc/articles/3520193">PMC Free Article</ext-link>]</comment><pub-id pub-id-type="doi">10.1259/dmfr/15182314</pub-id><pub-id pub-id-type="pmid">20100920</pub-id></element-citation></ref><ref id="ref18"><label>18</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Kamburoglu</surname><given-names>K</given-names></name><name><surname>Senel</surname><given-names>B</given-names></name><name><surname>Yuksel</surname><given-names>SP</given-names></name><name><surname>Ozen</surname><given-names>T</given-names></name></person-group><article-title>A comparison of the diagnostic accuracy of in vivo and in vitro photostimulable phosphor digital images in the detection of occlusal caries lesions</article-title><source><italic> Dentomaxillofac Radiol</italic></source><year> 2010</year><volume>39</volume><fpage>17</fpage><lpage>22</lpage><comment>[<ext-link ext-link-type="uri" xlink:href="http://www.ncbi.nlm.nih.gov/pmc/articles/3520404">PMC Free Article</ext-link>]</comment><pub-id pub-id-type="doi">10.1259/dmfr/91657756</pub-id><pub-id pub-id-type="pmid">20089739</pub-id></element-citation></ref><ref id="ref19"><label>19</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Senel</surname><given-names>B</given-names></name><name><surname>Kamburoglu</surname><given-names>K</given-names></name><name><surname>Ucok</surname><given-names>O</given-names></name><name><surname>Yuksel</surname><given-names>SP</given-names></name><name><surname>Ozen</surname><given-names>T</given-names></name><name><surname>Avsever</surname><given-names>H</given-names></name></person-group><article-title>Diagnostic accuracy of different imaging modalities in detection of proximal caries</article-title><source><italic> Dentomaxillofac Radiol</italic></source><year> 2010</year><volume>39</volume><fpage>501</fpage><lpage>11</lpage><comment>[<ext-link ext-link-type="uri" xlink:href="http://www.ncbi.nlm.nih.gov/pmc/articles/3520212">PMC Free Article</ext-link>]</comment><pub-id pub-id-type="doi">10.1259/dmfr/28628723</pub-id><pub-id pub-id-type="pmid">21062944</pub-id></element-citation></ref><ref id="ref20"><label>20</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Schropp</surname><given-names>L</given-names></name><name><surname>Alyass</surname><given-names>NS</given-names></name><name><surname>Wenzel</surname><given-names>A</given-names></name><name><surname>Stavropoulos</surname><given-names>A</given-names></name></person-group><article-title>Validity of wax and acrylic as soft-tissue simulation materials used in in vitro radiographic studies</article-title><source><italic> Dentomaxillofac Radiol</italic></source><year> 2012</year><volume>41</volume><fpage>686</fpage><lpage>90</lpage><comment>[<ext-link ext-link-type="uri" xlink:href="http://www.ncbi.nlm.nih.gov/pmc/articles/3528195">PMC Free Article</ext-link>]</comment><pub-id pub-id-type="doi">10.1259/dmfr/33467269</pub-id><pub-id pub-id-type="pmid">22933536</pub-id></element-citation></ref><ref id="ref21"><label>21</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Turkyilmaz</surname><given-names>I</given-names></name><name><surname>McGlumphy</surname><given-names>EA</given-names></name></person-group><article-title>Influence of bone density on implant stability parameters and implant success: a retrospective clinical study</article-title><source><italic> BMC Oral Health</italic></source><year> 2008</year><volume>8</volume><fpage>32</fpage><comment>[<ext-link ext-link-type="uri" xlink:href="http://www.ncbi.nlm.nih.gov/pmc/articles/2614413">PMC Free Article</ext-link>]</comment><pub-id pub-id-type="doi">10.1186/1472-6831-8-32</pub-id><pub-id pub-id-type="pmid">19025637</pub-id></element-citation></ref><ref id="ref22"><label>22</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Morea</surname><given-names>C</given-names></name><name><surname>Dominguez</surname><given-names>GC</given-names></name><name><surname>Coutinho</surname><given-names>A</given-names></name><name><surname>Chilvarquer</surname><given-names>I</given-names></name></person-group><article-title>Quantitative analysis of bone density in direct digital radiographs evaluated by means of computerized analysis of digital images</article-title><source><italic> Dentomaxillofac Radiol</italic></source><year> 2010</year><volume>39</volume><fpage>356</fpage><lpage>61</lpage><comment>[<ext-link ext-link-type="uri" xlink:href="http://www.ncbi.nlm.nih.gov/pmc/articles/3520242">PMC Free Article</ext-link>]</comment><pub-id pub-id-type="doi">10.1259/dmfr/13093703</pub-id><pub-id pub-id-type="pmid">20729185</pub-id></element-citation></ref><ref id="ref23"><label>23</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Gu</surname><given-names>L</given-names></name><name><surname>Yu</surname><given-names>LY</given-names></name><name><surname>Zhou</surname><given-names>Y</given-names></name><name><surname>Xie</surname><given-names>C</given-names></name></person-group><article-title>Application of the bone quality of pre-implanted mandible through optical density measurement</article-title><source><italic> Shanghai Kou Qiang Yi Xue</italic></source><year> 2008</year><volume>17</volume><fpage>479</fpage><lpage>82</lpage><pub-id pub-id-type="pmid">18989587</pub-id></element-citation></ref><ref id="ref24"><label>24</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Norton</surname><given-names>MR</given-names></name><name><surname>Gamble</surname><given-names>C</given-names></name></person-group><article-title>Bone classification: an objective scale of bone density using the computerized tomography scan</article-title><source><italic> Clin Oral Implants Res</italic></source><year> 2001</year><volume>12</volume><fpage>79</fpage><lpage>84</lpage><pub-id pub-id-type="doi">10.1034/j.1600-0501.2001.012001079.x</pub-id><pub-id pub-id-type="pmid">11168274</pub-id></element-citation></ref><ref id="ref25"><label>25</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Shapurian</surname><given-names>T</given-names></name><name><surname>Damoulis</surname><given-names>PD</given-names></name><name><surname>Reiser</surname><given-names>GM</given-names></name><name><surname>Griffin</surname><given-names>TJ</given-names></name><name><surname>Rand</surname><given-names>WM</given-names></name></person-group><article-title>Quantitative evaluation of bone density using the Hounsfield index</article-title><source><italic> Int J Oral Maxillofac Implants</italic></source><year> 2006</year><volume>21</volume><fpage>290</fpage><lpage>7</lpage><pub-id pub-id-type="pmid">16634501</pub-id></element-citation></ref><ref id="ref26"><label>26</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Mah</surname><given-names>P</given-names></name><name><surname>Reeves</surname><given-names>TE</given-names></name><name><surname>McDavid</surname><given-names>WD</given-names></name></person-group><article-title>Deriving Hounsfield units using grey levels in cone beam computed tomography</article-title><source><italic> Dentomaxillofac Radiol</italic></source><year> 2010</year><volume>39</volume><fpage>323</fpage><lpage>35</lpage><comment>[<ext-link ext-link-type="uri" xlink:href="http://www.ncbi.nlm.nih.gov/pmc/articles/3520236">PMC Free Article</ext-link>]</comment><pub-id pub-id-type="doi">10.1259/dmfr/19603304</pub-id><pub-id pub-id-type="pmid">20729181</pub-id></element-citation></ref><ref id="ref27"><label>27</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Nomura</surname><given-names>Y</given-names></name><name><surname>Watanabe</surname><given-names>H</given-names></name><name><surname>Honda</surname><given-names>E</given-names></name><name><surname>Kurabayashi</surname><given-names>T</given-names></name></person-group><article-title>Reliability of voxel values from cone-beam computed tomography for dental use in evaluating bone mineral density</article-title><source><italic> Clin Oral Implants Res</italic></source><year> 2010</year><volume>21</volume><fpage>558</fpage><lpage>62</lpage><pub-id pub-id-type="doi">10.1111/j.1600-0501.2009.01896.x</pub-id><pub-id pub-id-type="pmid">20443807</pub-id></element-citation></ref><ref id="ref28"><label>28</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Miles</surname><given-names>DA</given-names></name><name><surname>Danforth</surname><given-names>RA</given-names></name></person-group><article-title>A clinician’s guide to understanding cone beam volumetric imaging (CBVI)</article-title><source><italic>Peer-Reviwed Publication-Academy of Dental Therapeutics and Stomatology 2008</italic></source><year>2007</year></element-citation></ref><ref id="ref29"><label>29</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Nackaerts</surname><given-names>O</given-names></name><name><surname>Jacobs</surname><given-names>R</given-names></name><name><surname>Horner</surname><given-names>K</given-names></name><name><surname>Zhao</surname><given-names>F</given-names></name><name><surname>Lindh</surname><given-names>C</given-names></name><name><surname>Karayianni</surname><given-names>K</given-names></name><etal></etal></person-group><article-title>Bone density measurements in intra-oral radiographs</article-title><source><italic> Clin Oral Investig</italic></source><year> 2007</year><volume>11</volume><fpage>225</fpage><lpage>9</lpage><pub-id pub-id-type="doi">10.1007/s00784-007-0107-2</pub-id><pub-id pub-id-type="pmid">17668257</pub-id></element-citation></ref><ref id="ref30"><label>30</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Sakakura</surname><given-names>CE</given-names></name><name><surname>Giro</surname><given-names>G</given-names></name><name><surname>Goncalves</surname><given-names>D</given-names></name><name><surname>Pereira</surname><given-names>RM</given-names></name><name><surname>Orrico</surname><given-names>SR</given-names></name><name><surname>Marcantonio</surname><given-names>E Jr</given-names></name></person-group><article-title>Radiographic assessment of bone density around integrated titanium implants after ovariectomy in rats</article-title><source><italic> Clin Oral Implants Res</italic></source><year> 2006</year><volume>17</volume><fpage>134</fpage><lpage>8</lpage><pub-id pub-id-type="doi">10.1111/j.1600-0501.2005.01224.x</pub-id><pub-id pub-id-type="pmid">16584408</pub-id></element-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 003027 | SxmlIndent | more
Ou
HfdSelect -h $EXPLOR_AREA/Data/Pmc/Corpus/biblio.hfd -nk 003027 | 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= PMC:5654135
|texte= In vitro Evaluation of the Relationship between Gray Scales in Digital Intraoral Radiographs and Hounsfield Units in CT Scans
}}
Pour générer des pages wiki
HfdIndexSelect -h $EXPLOR_AREA/Data/Pmc/Corpus/RBID.i -Sk "pubmed:29082220" \
| HfdSelect -Kh $EXPLOR_AREA/Data/Pmc/Corpus/biblio.hfd \
| NlmPubMed2Wicri -a EdenteV2
| This area was generated with Dilib version V0.6.32. |  |