Pattern of lip competence and its association with malocclusion traits: a retrospective analysis of cases seen at a tertiary institution

Abstract

Background: The lips are central to facial aesthetics, but it is their competence pattern that determines whether they meet aesthetic standards or not. Aim: To assess the pattern of lip competence and its relationship to overjet and other malocclusion traits in patients seen at a tertiary hospital in South-South Nigeria and gender variations. Methods: A retrospective study was conducted from June 2015 to June 2025. Case notes of 454 orthodontic patients who attended the hospital’s orthodontic unit were reviewed. Case notes lacking complete information were excluded. Data on socio-demographics, overjet, molar relationship, and lip patterns were collected and analyzed using IBM SPSS version 26. Descriptive statistics (frequencies and percentages) and inferential statistics (Chi-square test) were used, with level of significance set at p < 0.05. Results: Of the 454 patients, 179 (39.4%) were males, and 275 (60.6%) were females, with a mean age of 15.36 ± 8.05 years. The 10–19-year age group had the highest representation (261, 57.5%). Incompetent lip seal was most prevalent in Angle’s Class II malocclusion (75.0%) and also common in Class I (65.3%) cases. Increased and normal overjet were significantly associated with incompetent lips (75.4% and 51.4%, respectively; p = 0.001). Incompetent lips were more common in females (61.8%). Conclusion: Incompetent lip seal was associated with both increased and normal overjet and was more associated with Angle’s class I malocclusion.