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PURPOSE The purpose of this study was to evaluate the effects of various protocols and systems for finishing and polishing monolithic zirconia on surface topography, phase transformation, and bacterial adhesion. MATERIALS AND METHODS Three hundred monolithic zirconia specimens were fabricated and then treated with three finishing and polishing systems (Jota [JO], Meisinger [ME], and Edenta [ED]) using four surface treatment protocols: coarse finishing alone (C); coarse finishing and medium polishing (CM); coarse finishing and fine polishing (CF); and coarse finishing, medium polishing, and fine polishing (CMF). Surface roughness, crystal phase transformation, and bacterial adhesion were evaluated using atomic force microscopy, X-ray diffraction, and streptococcal biofilm formation assay, respectively. One-way and two-way analysis of variance with Tukey post hoc tests were used to analyze the results (α=.05). RESULTS In this study, the surface treatment protocols and systems had significant effects on the resulting roughness. The CMF protocol produced the lowest roughness values, followed by CM and CF. Use of the JO system produced the lowest roughness values and the smallest biofilm mass, while the ME system produced the smallest partial transformation ratio. The ED group exhibited the highest roughness values, biofilm mass, and partial transformation ratio. CONCLUSION Stepwise surface treatment of monolithic zirconia, combined with careful polishing system selection, is essential to obtaining optimal microstructural and biological surface results.

Background The accurate assessment and acquisition of facial anatomical information significantly contributes to enhancing the reliability of treatments in dental and medical fields, and has applications in fields such as craniomaxillofacial surgery, orthodontics, prosthodontics, orthopedics, and forensic medicine. Mobile device–compatible 3D facial scanners have been reported to be an effective tool for clinical use, but the accuracy of digital facial impressions obtained with the scanners has not been explored. Objective We aimed to review comparisons of the accuracy of mobile device–compatible face scanners for facial digitization with that of systems for professional 3D facial scanning. Methods Individual search strategies were employed in PubMed (MEDLINE), Scopus, Science Direct, and Cochrane Library databases to search for articles published up to May 27, 2020. Peer-reviewed journal articles evaluating the accuracy of 3D facial models generated by mobile device–compatible face scanners were included. Cohen d effect size estimates and confidence intervals of standardized mean difference (SMD) data sets were used for meta-analysis. Results By automatic database searching, 3942 articles were identified, of which 11 articles were considered eligible for narrative review, with 6 studies included in the meta-analysis. Overall, the accuracy of face models obtained using mobile device–compatible face scanners was significantly lower than that of face models obtained using professional 3D facial scanners (SMD 3.96 mm, 95% CI 2.81-5.10 mm; z=6.78; P<.001). The difference between face scanning when performed on inanimate facial models was significantly higher (SMD 10.53 mm, 95% CI 6.29-14.77 mm) than that when performed on living participants (SMD 2.58 mm, 95% CI 1.70-3.47 mm, P<.001, df=12.94). Conclusions Overall, mobile device–compatible face scanners did not perform as well as professional scanning systems in 3D facial acquisition, but the deviations were within the clinically acceptable range of <1.5 mm. Significant differences between results when 3D facial scans were performed on inanimate facial objects and when performed on the faces of living participants were found; thus, caution should be exercised when interpreting results from studies conducted on inanimate objects.

The use of three-dimensional face-scanning systems to obtain facial models is of increasing interest, however, systematic assessments of the reliability of portable face-scan devices have not been widely conducted. Therefore, a systematic review and meta-analysis were performed considering the accuracy of facial models obtained by portable face-scanners in comparison with that of those obtained by stationary face-scanning systems. A systematic literature search was conducted in electronic databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for articles published from 1 January 2009 to 18 March 2020. A total of 2806 articles were identified, with 21 articles available for the narrative review and nine studies available for meta-analysis. The meta-analysis revealed that the accuracy of the digital face models generated by the portable scanners was not significantly different from that of the stationary face-scanning systems (standard mean difference (95% confidence interval) = −0.325 mm (−1.186 to 0.536); z = −0.74; p = 0.459). Within the comparison of the portable systems, no statistically significant difference was found concerning the accuracy of the facial models among scanning methods (p = 0.063). Overall, portable face-scan devices can be considered reliable for obtaining facial models. However, caution is needed when applying face-scanners with respect to scanning device settings, control of involuntary facial movements, landmark and facial region identifications, and scanning protocols.

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