Effect of dimensions on function: A 2-dimensional sonographic assessment to correlate facial muscle and smile type.

OBJECTIVE

The aim of this study was to measure the dimensions of the select facial muscles and correlate them with different types of smiles.

METHODS

The study group included 30 South Asian adults (17 men and 13 women) aged between 24 and 30 years divided into 3 groups of 10 subjects each according to Rubin's classification of smile. The zygomaticus major, levator labii superioris, depressor anguli oris, and mentalis muscles were ultrasonographically evaluated. The length and thickness of the muscles were measured bilaterally. The data obtained were analyzed statistically.

RESULTS

The maximum mean value thickness of the zygomaticus major was found in the canine smile group. The maximum mean value thickness of the depressor anguli oris and mentalis was seen in the full denture smile group. However, the thickness of the levator labii superioris muscle was similar between the different smile groups. There was no significant difference in the measurements of the length of the muscles between the right and the left sides.

CONCLUSIONS

This study did not find any statistically significant correlation between the type of smiles described in Rubin's classification and the dimensions of the associated facial muscle.