Soft tissue profile changes following maxillary protraction in Class III subjects

Abstract

The dentoskeletal effects of maxillary protraction (MP) therapy have been extensively investigated, while those relating to soft tissue profile changes are limited. Thus, the aim of this study was to determine the degree of soft tissue profile changes following MP therapy. The material consisted of the cephalometric films of 24 female subjects (12.69 +/- 1.08 years) with a Class III malocclusion who underwent MP therapy; these were compared with a control group of 15 females (12.13 +/- 0.63 years) with a Class I occlusion and matched for chronological age and observation period. Cephalometric films were available for all subjects before (T1) and after (T2) treatment/observation. The initial measurements and treatment/control changes were compared between the groups by means of a Student's t-test. The subjects in the MP group had a concave facial profile when compared with the controls. Comparison of the changes induced by MP therapy showed that the maxilla and surrounding soft tissues showed significant anterior movement (P < 0.001), whereas the mandible and surrounding soft tissues showed a backward and downward rotation. The improvement in facial profile predominantly resulted from maxillary soft tissue changes and mandibular hard tissue changes. The concave soft tissue profiles of the Class III subjects were corrected by anterior movement of the maxilla and a concomitant increase in the fullness of the upper lip. The concave skeletal profiles were, however, corrected mainly by backward and downward rotation of the mandible.