Changes in the mandibular angle during adulthood in South Africans

Abstract

OBJECTIVES : The purpose of this study was to measure the mandibular angle as a reflection of the biomechanical forces acting on the mandible and relate it to aging and loss of teeth. METHODS : A total of 717 mandibles of adult individuals were selected from the Pretoria Bone Collection. These mandibles were allocated to dentition subgroups according to their pattern of tooth loss. The angle of the mandible was measured with a mandibulometer. The variation in the mandibular angle was statistically analyzed by age regressions and comparisons between adjusted means of dentition subgroups. RESULTS : Aging per se was not associated with a greater mandibular angle. With limited tooth loss, aging was associated with a smaller mandibular angle in females. Generally the mandibular angle increased with tooth loss and was accentuated when an even occlusion pattern was lost rather than with more extensive tooth loss. A more pronounced increase in mandibular angle with tooth loss was noted in females and individuals of European ancestry. CONCLUSIONS : Tooth loss and not aging is associated with an increase in the mandibular angle. Masculinity and being from African ancestry provided some protection against an increase in the mandibular angle with tooth loss. The accentuated increase in the mandibular angle when an even occlusion pattern was disturbed supports the notion that an uneven loss of teeth was indeed associated with inefficient mastication. The unexpected decrease in angle noted in females with aging but limited tooth loss may be indicative of constructive changes beyond puberty.