Lip profile changes in patients with Class II Division 1 malocclusion of varied growth patterns treated with maxillary premolar extractions: A pilot study

Abstract

This retrospective pilot study assessed the pre- and posttreatment lip profile changes among adult patients with Class II Division 1 malocclusion of varied growth patterns and compared these changes with patients with a skeletal Class I relationship, to identify the dental, skeletal, and soft tissue cephalometric variables that altered the posttreatment lip profile. A total of 33 digital cephalograms were divided into 4 study groups based on the mandibular plane (Mp-SN) angle: group 1 (control, skeletal Class I; mean angle=21.5°) (n=8), group 2 (Class II Division 1 malocclusion; low angle=<26°) (n=8), group 3 (Class II Division 1 malocclusion; intermediate angle=26°-38°) (n=9), and group 4 (Class II Division 1 malocclusion; high angle=>38°) (n=8). We observed a significant decrease in SNA, ANB, maxillary incisor to NA (degrees and millimeters), and soft tissue parameters, especially lip strain and lower lip to E line and upper lip to E line. Posttreatment intergroup comparison showed a significant increase of Mp-SN, and this increase was greater in group 3, followed by group 4 as compared with group 1. In addition, statistically significant differences in SNA, ANB, mandibular incisor to NB (degrees) and IMPA, and H angle in groups 2-4 were observed. Patients with Class II Division 1 malocclusion showed a significant decrease in SNA, ANB, maxillary incisor to NA, and all soft tissue parameters in posttreatment compared with group 1. Thus, the soft tissue changes resulted in a similar profile to patients in group 1, who are considered to have an aesthetically pleasing posttreatment profile.