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Influence of lip form on the perceived ideal incisal show at rest
Chee Weng Yong1, Li Xuan Lee1, Jun Jie Lee1
1Faculty of Dentistry, National University of Singapore, Singapore.
Introduction:
A widely used guide of 2 mm incisal show at rest is used as an esthetic guide in treatment planning for many patients. However, this does not consider the lip form at rest. This study aimed to investigate the most esthetic incisal show at rest, at varying lip forms, perceived by dental professionals and laypeople.
Methods:
Three volunteers of each gender and type of lip form (straight, moderate, and high) were recruited. For each volunteer, 6 images of their perioral region with a variable incisal display at rest were generated. A survey was conducted whereby respondents were asked to grade the attractiveness of each image using a numerical visual analog scale from 0-10.
Results:
A survey sample of 107 respondents participated in the study (male-to-female ratio = 37 to 70; dental professionals-to-laypeople ratio = 50 to 57). Mann-Whitney U-test was used to analyze the differences in preferences between the various groups (P <0.05). Both dental professionals and laypeople responded that 2 mm incisal show at rest is only suitable for patients with straight lip form. However, for patients with moderate or high lip forms, an incisal show of 4-5 mm was preferred. There was also no significant difference between the perceived ideal incisal show of dental professionals and laypeople, except for the ideal incisal show of models with straight lip form.
Conclusions:
The guide of 2 mm incisal show at rest is appropriate only for patients with straight lip form. Patients with moderate or high lip form should have a greater incisal show. This finding was agreed on by both dental professionals and laypeople, regardless of their gender.
