Influence of Midline Position and Incisal Inclination on Esthetic Evaluation of Complete Denture Wearers

Purpose: This study was conducted to determine the esthetically acceptable range of deviation of the midline position and incisal inclination of complete dentures, based on the results of esthetic evaluation conducted under various midline positions and degrees of incisal inclination in complete denture wearers. In addition, the influence of anatomic landmarks of the face in the evaluation of the midline position was also examined.Methods: Frontal pictures of each of 10 complete maxillomandibular denture wearers were taken, with the lips opened in the intercuspal position. Each image was processed to yield 21 images with varying midline positions (±2.5 mm at 0.5-mm intervals) and varying degrees of incisal inclination (±2.5 degrees at 0.5-degree intervals) for evaluation. These images were presented to the examiners (20 dentists and 20 dental students), who gave a score of 0 to the images that appeared esthetically unacceptable, 1 to those that appeared neutral, and 2 to those that appeared esthetically acceptable. The scores of each image were totalled to yield the natural appearance score. We checked for significant differences in the natural appearance score between control images and each of the images evaluated in this study.Results: No significant difference in the natural appearance score was noted when the midline deviation was within ±1 mm (in the evaluation by dentists) or ± 1.5 mm (in the evaluation by students) (P>0.05). In addition, no significant difference in the score was noted when the incisal inclination was between −2 and +1.5 degrees (in the evaluation by dentists) or between −2.5 and +2 degrees (in the evaluation by students) (P>0.05).Conclusion: The results suggest that in complete denture wearers, midline deviation within ±1 mm and incisal inclination within ±1.5 degrees are esthetically acceptable.