Factors affecting changes in soft tissue profile after various treatment modalities for skeletal Class II malocclusion: A cross-sectional study

Abstract

Various treatment modalities are used to treat skeletal Class II malocclusion with different effects on the soft tissue. This study was aimed to determine factors affecting changes in soft tissue profile after various treatment modalities for skeletal Class II malocclusion. A cross-sectional study was conducted using pre-treatment and post-treatment lateral cephalograms of 141 subjects. The sample consisted of 47 patients treated with Clark's Twin Block, 47 with first premolar extractions, and 47 with Class II elastics. The post-treatment cephalograms were superimposed on pre-treatment radiographs using stable landmarks: anterior wall of sella turcica and anterior cranial base. The changes in profile were evaluated by paired t-test using X-Y co-ordinate system. Changes in profile were predicted by using multi-variable linear regression analysis. Level of significance was kept at P≤0.05. The changes in soft tissue profile were statistically significant for all the landmarks (P<0.001) of nose, upper and lower lip, and chin in horizontal and vertical direction, except subnasale and labrale superius in the horizontal direction. The soft tissue profile changes can be predicted for all landmarks with various prediction powers except pronasale, subnasale, and inferior labial sulcus in the vertical direction. Almost all the soft tissue landmarks of nose and lower third of the face exhibit downward and forward movement. The changes in the upper lip in both horizontal and vertical directions were found to be more predictable than those occurring in the lower lip.