The molecular and cellular effects of ageing on the periodontal ligament.

Abstract

Many in vitro studies have investigated age-related biological changes in cells comprising the periodontium but the basic question of whether the periodontium can maintain its integrity with age remains unanswered. Thus, the aim of this study was to understand how, in the absence of disease, advancing age impacts the structure of the periodontium. Of 4, 10, 25, and 50-week-old mice were examined using histology and immunohistochemical analyses for cell proliferation, cell turnover, collagen quantity and quality, osteogenic markers, bone turnover, and cytokine expression. The periodontal ligament (PDL) space shows a gradual decrease in width over the lifespan of the mice. Cell proliferation as well as the quantity and quality of collagen fibres decreased with age although cell density did not appear to be altered. Osteoprogenitor markers in the PDL maintained their expression with increasing age. Alkaline phosphatase (ALP) activity decreased, but osteoclast activity increased with age. Ageing is associated with a decline in the quality and quantity of collagen and an increase in bone resorption, all of which can diminish the function of the periodontium even in the absence of disease.