Soft tissue profile analysis in a sample of South African Blacks with bimaxillary protrusion

Evaluation of facial proportions and shape is one of the most important steps in determining treatment options and outcomes for the orthodontist and maxillo-facial surgeon. Balancing the position of the lips in relation to the nose and chin has a direct relationship with the patient's aesthetic preference.

The purpose of this study was to analyse the soft tissue profile preferences in a sample of South African Blacks and to establish a Profile Index for bimaxillary protrusion.

An earlier study by Beukes, Dawjee and Hlongwa was undertaken to determine facial profile perceptions by a group of South African Black evaluators. Adjudicators were drawn from Black students from Medunsa campus, University of Limpopo, the Holy Trinity secondary school and the Mphwe secondary school, and had to evaluate silhouetted facial profiles of 30 bimaxillary dento-alveolar protrusive patients. After an initial group of 128 Black evaluator chose 13 profiles as the most attractive and most unattractive, a second group of 605 Black evaluators (also drawn from the same academic institutions) chose three profiles as acceptable and four profiles as unacceptable. From this final selection, a soft tissue analysis was undertaken to evaluate the nasolabial angle, nasofacial angle, the facial contour angle, the lower lip-chin-throat angle and the lower and upper lip prominence in relation to the Burstone "B"- line. A Fisher exact test was done to determine the statistical difference between the mean values for the acceptable and unacceptable profiles.

The three acceptable profiles, which were chosen by more than 69% of the evaluators, had a lip prominence of 5 to 6mm more than their African American counterparts. The angular measurements of the nose, lip and chin were in close proximity to the values given by Naidoo and Miles and Flynn et al. The three acceptable profiles had normal overjet, overbite, minimal incisor visibility and efficient lip function.

A "Profile index for bimaxillary protrusion" has been concluded from this study and proposes acceptable soft tissue values for bimaxillary protrusive Black South Africans.