Factors affecting perception of laypeople and dental professionals toward different smile esthetics.

Abstract Background: /purpose: Several factors such as identity, income, and age potentially associated with smile perceptions. This study aimed to identify the factors affecting the smile esthetic perception in different identities (layperson, general dentist and orthodontist) and to detect the extent of their association with smile perception. Materials and methods: Extraoral photographs in frontal, lateral, and three-quarter views were shot and adjusted on Adobe Photoshop into 95 smile photographs with different smile patterns. Based on these photographs, the investigators were asked to fill the online questionnaire. Pearson chi-square test and logistic regression were used for statistical analyses. Results: Identity, gender, age, and treatment experience were noted to affect smile esthetic perception. In addition, the perception of smile esthetics was significantly different among frontal, lateral, and three-quarters views regarding the arc ratio, most posterior teeth exposure, upper teeth exposure, and lower teeth exposure. Conclusion: Identity, gender, age, and treatment experience influence the smile esthetics perception, with a significant difference in the results of the esthetic perception based on the 3 smile views. Of all demographic factors, identity had a strong relation to the perception of smile attractiveness. Nevertheless, additional studies are needed to realize how the demographic factors influence people's perception of smile esthetics, particularly in the three-quarter and lateral views.

Location of the mandibular canal and thickness of the occlusal cortical bone at dental implant sites in the lower second premolar and first molar.

The objective of this study was to evaluate the location of the mandibular canal and the thickness of the occlusal cortical bone at dental implant sites in the lower second premolar and lower first molar by using dental cone-beam computed tomography (CBCT). Seventy-nine sites (47 second premolar and 32 first molar sites) were identified in the dental CBCT examinations of 47 patients. In this study, 4 parameters were measured: (1) MC-the distance from the mandibular canal to the upper border of the mandible; (2) CD-the distance from the mandibular canal to the buccal border of the mandible; (3) MD-the distance from the mandibular canal to the lingual border of the mandible; (4) TC-the thickness of the cortical bone at the occlusal side. A statistical analysis was employed to compare the size and differences between these 4 parameters at the lower second premolar and lower first molar. Regarding the MC and MD, the experimental results showed no statistical difference between the first molar and second premolar. However, the TC for the second premolar was greater than that of the first molar. Thus, careful consideration is necessary in choosing the size of and operation type for dental implants.