Objective: To correlate the clinical perception of maxillary incisor inclination from photographs of the smiling face with cephalometric measurements, using conventional incisor axis reference points and crown reference points.
Design: Cross-sectional study.
Setting: Department of Orthodontics, School of Dentistry, University of Lisbon (Portugal).
Participants: Eight orthodontists.
Methods: The perception of maxillary incisor inclination of 47 female patients (mean age 23.4 ± 1.5 years) was evaluated by eight orthodontists. The participants' photographs (smiling frontal, smiling three-quarter and smiling profile) were shown to each assessor and a continuous visual analogue rating scale was used to assess the perception of maxillary incisor inclination. Pearson's correlation and linear regression were calculated between each cephalometric measurement and the perception of incisor inclination.
Results: Anatomical crown inclination measurements U1ac-FH (r = 0.854; P < 0.01) and U1ac-SN (r = 0.845; P < 0.01) had the highest correlation values with the assessors' perception of maxillary incisor inclination. Conventional incisor axis measurements showed the lowest correlation values (r = 0.668-0.756).
Conclusion: Cephalometric measurements of the labial surface of the anatomical crown of the maxillary incisors showed the strongest correlations with the clinical perception of maxillary incisor inclination from photographs. For optimal aesthetics, the inclination of the labial surface of maxillary incisor crown should be evaluated.
Keywords: Cephalometrics; aesthetics; incisor inclination; perception; photographs; smile.