锥形束CT转化头颅侧位片定点精确性的研究

Objective In this study, we compared the precision of landmark identification using cephalograms from cone-beam computed tomographic (CBCT) volumes and conventional lateral cephalograms (Ceph). Methods Twenty pre-orthodontic patients were radiographed with conventional Ceph and CBCT techniques. CBCT data was uploaded into InvivoDental software 5.0 to generate cephalograms(CCB). Three observers plotted 23 landmarks using computer displays of CCB and Ceph views during separate sessions. Absolute differences between CCB and Ceph of all observers were measured. The absolute difference between each observer was also measured. ANOVA and paired t tests were used to analyze variability differences. Results The difference of landmark identification between CCB and Ceph were significant at P＜0.05 calculations. 8 landmarks variability was statistically greater than Ceph views. The variability of CCB for each observer was consistently greater than in Ceph. The overall correlation of CCB and Ceph measurements was excellent at 0.99.Conclusions The CCB displays of CBCT volume images provide generally more precise identification than Ceph. More precise location of basion, porion, orbitale, ANS, A point, Gonion and tooth apex overcomes the problem of superimposition of these bilateral landmarks seen in Ceph. Greater variability of certain landmarks is probably related to inadequate definition of the landmarks in the third dimension.     

分光光度法与目测法测量义齿基托树脂色稳定性的比较研究

Objective To explore the relationship between the spectrophotometric and visual methods in evaluating the color stability of denture base resin, and determine the threshold color difference of denture base resin in the spectrophotometric method. Methods Two kinds of denture base resin were respectively fabricated into 33 specimens whose color differences varied from indistinguishable to obvious.Each of the specimens was assessed respectively by 30 human observers and a SP62 spectrophotometer. The results of visual assement were recorded as "indistinguishable change", "light change" or "severe change",while the spectrophotometric color differences ( △ E) were calculated. In each group, a logistic curve was explored to determine the relationship between the color difference ( △ E) and the ratio of "severe change".Results The R squares of logistic curves were 0. 93 and 0. 94 respectively. The threshold color differences in the spectrophotometric method were 2. 87 and 2. 82 respectively. Conclusions A high relevance between the spectrophotometric and visual methods in evaluating the color stability of denture base resin was found.The threshold color differences for different color denture base resins were similar.     

不锈钢方丝口腔内应用后表面摩擦力及表面形态变化的研究

Objective The purpose of this study was to investigate the changes of surface frictional forces and surface topography of used-stainles steel(ss) archwires. Method On the testing mandibular model,we measured the static and kinetic friction between the used and unused archwires at different time points and they were examined in the space closure phase. Surface topography of each type archwire was assessed by scanning electron microscope(SEM). Results The surfacial friction of ss archwires used three months are greater than the unused one (P＜0. 05), while much greater than that used after four and five months (P＜0. 01). SEM: The surfacial smooth finish of ss archwires were reduced with the longer time of use, whereas surface roughness were increased. Conclusion The roughness changes on the ss archwires' surfacial structure suggested us to change the archwires in time or increase the anchorage.     

应用锥形束CT评估腭部种植体的植入部位

Objective To investigate the vertical bone height and the bone density of the palate for implants placement using cone beam CT(CBCT)and to provide references to the safe and stable placement of palatal implants.Methods Three-dimensional reformatting images were reconstructed with the selected CBCT scanning data of 34 patients aged 18 to 35 yeras,by means of EZ implant software.The vertical bone height was measured at 20 interesting sites of palate.Bone density was measured at 10 sites that could support 3.0mm long implants.The data of the vertical bone height and bone density were analyzed by Kmeans cluster analysis.Results According to the cluster analysis results,the 10 sites were classified into 3 clusters.There were statistical differences among these three clusters in bone height and bone density(P＜0.05).The ISD result showed that the greatest mean value of vertical bone height was obtained in cluster 2,followed by cluster 1 and cluster 3;the highest bone density was founded in cluster 3,followed by cluster 1 and cluster 2.Conclusions Evaluation of the sites for palatal implant placement with cone beam CT would be helpful in safe and stable implantation.     

应用锥形束CT评估腭部种植体的植入部位

Objective To investigate the vertical bone height and the bone density of the palate for implants placement using cone beam CT(CBCT)and to provide references to the safe and stable placement of palatal implants.Methods Three-dimensional reformatting images were reconstructed with the selected CBCT scanning data of 34 patients aged 18 to 35 yeras,by means of EZ implant software.The vertical bone height was measured at 20 interesting sites of palate.Bone density was measured at 10 sites that could support 3.0mm long implants.The data of the vertical bone height and bone density were analyzed by Kmeans cluster analysis.Results According to the cluster analysis results,the 10 sites were classified into 3 clusters.There were statistical differences among these three clusters in bone height and bone density(P＜0.05).The ISD result showed that the greatest mean value of vertical bone height was obtained in cluster 2,followed by cluster 1 and cluster 3;the highest bone density was founded in cluster 3,followed by cluster 1 and cluster 2.Conclusions Evaluation of the sites for palatal implant placement with cone beam CT would be helpful in safe and stable implantation.     

应用锥形束CT评估腭部种植体的植入部位

Objective To investigate the vertical bone height and the bone density of the palate for implants placement using cone beam CT(CBCT)and to provide references to the safe and stable placement of palatal implants.Methods Three-dimensional reformatting images were reconstructed with the selected CBCT scanning data of 34 patients aged 18 to 35 yeras,by means of EZ implant software.The vertical bone height was measured at 20 interesting sites of palate.Bone density was measured at 10 sites that could support 3.0mm long implants.The data of the vertical bone height and bone density were analyzed by Kmeans cluster analysis.Results According to the cluster analysis results,the 10 sites were classified into 3 clusters.There were statistical differences among these three clusters in bone height and bone density(P＜0.05).The ISD result showed that the greatest mean value of vertical bone height was obtained in cluster 2,followed by cluster 1 and cluster 3;the highest bone density was founded in cluster 3,followed by cluster 1 and cluster 2.Conclusions Evaluation of the sites for palatal implant placement with cone beam CT would be helpful in safe and stable implantation.     

应用锥形束CT评估腭部种植体的植入部位

Objective To investigate the vertical bone height and the bone density of the palate for implants placement using cone beam CT(CBCT)and to provide references to the safe and stable placement of palatal implants.Methods Three-dimensional reformatting images were reconstructed with the selected CBCT scanning data of 34 patients aged 18 to 35 yeras,by means of EZ implant software.The vertical bone height was measured at 20 interesting sites of palate.Bone density was measured at 10 sites that could support 3.0mm long implants.The data of the vertical bone height and bone density were analyzed by Kmeans cluster analysis.Results According to the cluster analysis results,the 10 sites were classified into 3 clusters.There were statistical differences among these three clusters in bone height and bone density(P＜0.05).The ISD result showed that the greatest mean value of vertical bone height was obtained in cluster 2,followed by cluster 1 and cluster 3;the highest bone density was founded in cluster 3,followed by cluster 1 and cluster 2.Conclusions Evaluation of the sites for palatal implant placement with cone beam CT would be helpful in safe and stable implantation.     

应用锥形束CT评估腭部种植体的植入部位

Objective To investigate the vertical bone height and the bone density of the palate for implants placement using cone beam CT(CBCT)and to provide references to the safe and stable placement of palatal implants.Methods Three-dimensional reformatting images were reconstructed with the selected CBCT scanning data of 34 patients aged 18 to 35 yeras,by means of EZ implant software.The vertical bone height was measured at 20 interesting sites of palate.Bone density was measured at 10 sites that could support 3.0mm long implants.The data of the vertical bone height and bone density were analyzed by Kmeans cluster analysis.Results According to the cluster analysis results,the 10 sites were classified into 3 clusters.There were statistical differences among these three clusters in bone height and bone density(P＜0.05).The ISD result showed that the greatest mean value of vertical bone height was obtained in cluster 2,followed by cluster 1 and cluster 3;the highest bone density was founded in cluster 3,followed by cluster 1 and cluster 2.Conclusions Evaluation of the sites for palatal implant placement with cone beam CT would be helpful in safe and stable implantation.     

应用锥形束CT评估腭部种植体的植入部位

Objective To investigate the vertical bone height and the bone density of the palate for implants placement using cone beam CT(CBCT)and to provide references to the safe and stable placement of palatal implants.Methods Three-dimensional reformatting images were reconstructed with the selected CBCT scanning data of 34 patients aged 18 to 35 yeras,by means of EZ implant software.The vertical bone height was measured at 20 interesting sites of palate.Bone density was measured at 10 sites that could support 3.0mm long implants.The data of the vertical bone height and bone density were analyzed by Kmeans cluster analysis.Results According to the cluster analysis results,the 10 sites were classified into 3 clusters.There were statistical differences among these three clusters in bone height and bone density(P＜0.05).The ISD result showed that the greatest mean value of vertical bone height was obtained in cluster 2,followed by cluster 1 and cluster 3;the highest bone density was founded in cluster 3,followed by cluster 1 and cluster 2.Conclusions Evaluation of the sites for palatal implant placement with cone beam CT would be helpful in safe and stable implantation.     

应用锥形束CT评估腭部种植体的植入部位

Objective To investigate the vertical bone height and the bone density of the palate for implants placement using cone beam CT(CBCT)and to provide references to the safe and stable placement of palatal implants.Methods Three-dimensional reformatting images were reconstructed with the selected CBCT scanning data of 34 patients aged 18 to 35 yeras,by means of EZ implant software.The vertical bone height was measured at 20 interesting sites of palate.Bone density was measured at 10 sites that could support 3.0mm long implants.The data of the vertical bone height and bone density were analyzed by Kmeans cluster analysis.Results According to the cluster analysis results,the 10 sites were classified into 3 clusters.There were statistical differences among these three clusters in bone height and bone density(P＜0.05).The ISD result showed that the greatest mean value of vertical bone height was obtained in cluster 2,followed by cluster 1 and cluster 3;the highest bone density was founded in cluster 3,followed by cluster 1 and cluster 2.Conclusions Evaluation of the sites for palatal implant placement with cone beam CT would be helpful in safe and stable implantation.