Changes in incisor relationship over the life course - Findings from a cohort study

Abstract

Objective: The aim of this longitudinal cohort study was to investigate the changes in incisor relationship over ‎three decades from adolescence to mid-adulthood.‎

Materials and Methods: The sample included 1,037 children (48.4% female) born between April 1972 and March 1973 from the ‎longitudinal birth cohort Dunedin Multidisciplinary Health and Development Study. Overjet and ‎overbite values were assessed at age 15 and 45 years and entered in a regression model as outcome ‎variables. Baseline occlusal variables, sex, history of orthodontic treatment, periodontal data recorded ‎at age 38, and selfreported oral parafunction and orthodontic treatment history recorded at age 45 ‎were entered as covariates in the regression analysis.‎

Results: Regression modelling showed that overjet/overbite category (high or low) at age 15 tends to predict ‎overjet/overbite category at age 45, with overjet become slightly larger (around +0.5 mm) and ‎overbite slightly lower (-0.5 mm) over time. Study members with self-reported tooth clenching had a ‎slighter greater overbite (+0.3 mm) at age 45 than those who did not. Additionally, those with signs of ‎periodontal disease at age 38 had a slightly larger overjet (+0.5 mm) at age 45 than those without ‎disease. Sex differences were demonstrated with females having 0.6 mm larger overjet, and 0.4 mm ‎overbite at age 45.‎

Conclusions: Overall, overjet values tend to be higher during mid-adulthood than during adolescence, while the ‎converse is true for overbite. There appears to be a degree of sexual dimorphism in overjet and ‎overbite values later in life. Clinical Significance: Incisor relationships change during the life course and ‎are related to ageing, sex, periodontal health, and parafunctional habits. Clinicians and educators ‎should be aware of these changes when making treatment decisions that alter incisor relationship.‎