Dentoalveolar and Smile Aesthetic Changes Following Fixed Orthodontic Treatment in Adults with Varying Anterior Overjet: A Retrospective Study

Abstract

Introduction: Anterior overjet is a key determinant of dentofacial aesthetics and occlusal function, and its correction is a primary objective of fixed orthodontic therapy. It is still unclear how baseline overjet magnitude affects dentoalveolar adaptation during orthodontic treatment in adults. Although fixed appliance therapy routinely addresses excessive overjet, no single study has directly compared whether patients grouped by initial overjet category respond differently- or whether any such differences carry through to smile aesthetic parameters. Aim: To compare skeletal, dental, and smile aesthetic changes after comprehensive fixed orthodontic treatment in 30 adult patients, divided into three groups by baseline anterior overjet (OJ): normal (0-4 mm), excessive (>4 mm), and negative/reverse (<0 mm). Materials and Methods: This retrospective observational study was conducted at the Department of Orthodontics at Dr DY Patil Dental College and Hospital, Pimpri, Pune, Maharashtra, India using treatment records of patients treated between 2018 and 2024; the study itself was planned, executed, and analysed between January 2024 and February 2025 Thirty patients satisfied all inclusion criteria and were assigned to three groups of 10 on the basis of baseline anterior overjet: Group 1 (normal overjet, 0-4 mm), Group 2 (excessive overjet, >4 mm), and Group 3 (negative/reverse overjet, <0 mm). Pre- and post-treatment lateral cephalograms and standardised frontal smile photographs were assessed across 21 parameters - 7 skeletal, 7 dental, and 7 smilerelated. Within-group changes were tested with paired-samples t-tests; between-group treatment change scores were compared using One-way Analysis of Variance (ANOVA) with Tukey HSD post-hoc testing (α=0.05). Results: Group 2 (excessive overjet) showed the greatest and most consistent dentoalveolar response: U1-NA (mm) reduced by 4.00 mm (p=0.004), U1-NA° by 11.80° (p=0.004), L1-NB° by 4.00° (p=0.034), and U1-PP° increased by 16.90° (p = 0.003), with concurrent SNA reduction of 2.20° (p=0.002) and ANB reduction of 1.40° (p=0.039). Group 1 (normal overjet) showed significant retroclination of U1-NA° (6.70°; p=0.016), U1-NA (mm) reduction (p = 0.041), U1-PP° change (p=0.020), and a significant decrease in interlabial gap (p=0.035). Group 3 (negative overjet) showed no statistically significant change in any parameter. Between-group ANOVA confirmed significant differences for U1-NA° (F=3.665; p=0.042) and U1-PP° (F=4.938 p=0.016). Smile Index increased significantly within Group 2 (p=0.043); all other smile parameters were non significant across all groups. Conclusion: Fixed orthodontic treatment produced dentoalveolar changes that scaled with baseline overjet severity. Adults with excessive overjet showed the most pronounced skeletal and dental changes, particularly in upper incisor inclination. Larger prospective trials are required to determine treatment sensitivity for these indices because smile aesthetic measures were mostly insensitive to tooth movement in study design.