Abstract
Introduction: It has been suggested that certain features of occlusion that lay outside what is considered ‘normal’ have the potential to affect risk for temporomandibular joint disorders and incisor stability. This concept is highly controversial within the dental literature and previous research findings on associations are inconsistent.
Objectives: The research objectives were to a) investigate the association of commonly cited occlusal features during adolescence and temporomandibular joint clicking at age 45, and b) explore the changes that occur to the incisor relationship from adolescence to age 45.
Materials and Methods: The sample used were members of the Dunedin Multidisciplinary Health and Development Study (DMHDS), a longitudinal birth cohort study investigation of 1,037 children (48.4% female) born at Queen Mary Hospital, Dunedin, New Zealand between 1 April 1972 and 31 March 1973. For a) associations between specific putative occlusal risk factors (posterior cross-bite, overbite and overjet) at age 15, and TMJ outcomes (both self-reported and clinically assessed) at age 45 were studied. For b) changes in overjet and overbite values were observed by grouping these individuals into low, normal and high categories at age 15, which were then compared to age 45 measures.
Results: The presence of posterior cross-bite, or abnormal overjet/overbite values during adolescence were not associated with TMJ clicking at age 45. Associations were found between self-reported history of tooth clenching and personality characteristics appear to be associated with self-reported clicking of the TMJ later in life. Additionally, there is a suggestion that high overbite during adolescence is associated with less risk for TMJ clicking later in life. Self-reported history of orthodontic treatment was not associated with TMJ outcomes.
For incisor relationshipchanges,mean overjet values were0.5 mm higher,and mean overbite values were 0.5 mm lower at age 45 than atage 15. Regression modelling showed that overjet/overbite category (high or low) at age 15 tends to predict overjet/overbite category at age 45. Study members who self-reported tooth clenching had 0.3 mm more overbite at age 45 than those who did not self-report the habit. Additionally, those with signs of periodontal disease (5 + mm attachment loss) at age 38 had 0.5 mm more overjet at age 45 thanthose without disease. Sex differences were demonstrated with females having0.6 mm more overjet, and 0.4 mm overbite at age 45.
Conclusions: The findings suggest that common occlusal featuresin adolescence are not associated with higherprevalence of TMJ clicking later in life.Personality appears influence self-reports of signs and symptoms of TMD, which may need to be considered in future research. The findings do not support the provision of orthodontic treatmentto reduce signs and symptoms of TMD later in life. The findings alsoindicate that overall overjet values tend to be higher during mid-adulthood than duringadolescence, while the converse is true for overbite. There appears to be a degree of sexual dimorphism in overjet and overbite values later in life.