Faculty Bibliography

Background/purpose/UNASSIGNED:With the rise of digitalization in dentistry, intraoral scanners and digital impressions have recently been adopted by many clinicians. The aim of this study was to investigate surface topography of prepared teeth and the accuracy of digital impressions. Materials and methods/UNASSIGNED:Twenty mandibular typodonts, containing left first premolar and left first molar abutment teeth manufactured by using CAD/CAM, were used in this study. An intraoral scanner was used to scan each typodont, and each STL file generated was exported in high resolution (Group H), moderate resolution (Group M), and low resolution (Group L). All 60 files were inspected in a 3-D mesh processing software. For each file, the number of triangulation points in the meshwork were obtained for both abutment teeth. Results/UNASSIGNED:The measurements obtained from the 3-D mesh processing software revealed that the mean number of triangulation points on the 3-D surface of the abutment teeth (20 premolars + 20 M) were 790,625 ± 98,890 dots in Group H, 592,283 ± 74,881 dots in Group M, and 198,067 ± 19,328 dots in Group L. Significant differences were found between Group H and M (p < 0.05), Group H and L (p < 0.001), and Group M and L (p < 0.01). Conclusion/UNASSIGNED:The outcomes of this study reveal that there are strong correlations between the data quality of digital impressions and surface topography of prepared teeth. Therefore, the utilization of STL files in high resolution format is the recommended choice for clinicians engaging in a digital workflow process.

PURPOSE:To evaluate the biologic, technical, and radiographic outcomes of CAD/CAM-milled bilayer and monolithic zirconia crowns using implants and Ti-base abutments with up to 5 years of follow-up. MATERIALS AND METHODS:A total of 182 implant-supported "screw-mentable" (hybrid screw/cement retention) single crowns were evaluated in 118 patients. Ti-base abutments were selected according to the chimney (3.5 or 5 mm) and gingival (1, 2, or 3 mm) heights in the virtual model. Zirconia crowns were designed using CAD/CAM software and then milled from partially stabilized zirconia blocks. After all crowns were cemented onto Ti-base abutments, they were clinically screwed onto the implants. Both implants and crowns were followed up for up to 5 years, and their clinical, technical, and radiologic results were recorded. RESULTS:A total of 118 patients (86 women and 32 men) who received 182 implant-supported screw-mentable crowns were included in this study. The mean follow-up period was 32 ± 18 months (range: 24 to 60 months) for all implants and crowns. No implant was lost during the follow-up period, yielding a cumulative implant survival rate of 100%. Two technical complications were observed in two bruxer patients, yielding a cumulative restoration survival rate of 98.9%. The marginal bone loss was 0.7 ± 0.5 mm from the baseline radiograph to the radiograph taken at the final recall visit. No implants were diagnosed with peri-implantitis. CONCLUSION:The outcomes of this study suggest that Ti-base abutments are a feasible and affordable alternative to CAD/CAM abutments and that they can successfully support single zirconia crowns.