A light microscopic study of the attachment mechanism in different kinds of adhesive lines in rat molars

Summary This study was designed to observe drifting molars of 70-day-old rats by light microscopy, and to elucidate whether there are similar attachment mechanisms at different kinds of adhesive lines in periodontal mineralized tissue of the rat molar region. Three kinds of adhesive lines — cement lines on resorbed alveolar bone, cement lines on resorbed roots, and cemento-dentinal junctions were examined. The two kinds of cement lines showed similar histological and histochemical features, they were proteoglycan-rich and fiber-poor. They appeared to form on the resorbed tissue before principal fiber reattachment. After covering by new bone or by reparative cementum, the cement lines retained the original features. The cemento-dentinal junction showed features very similar to those of the cement lines. Previous studies have suggested that the cemento-dentinal junctions bind the cementum and dentine by adhesion of proteoglycans. Structural similarities suggest that cement lines provide similar links between new bone and resorbed bone and between resorbed root and reparative cementum. In conclusion, this study suggests that there is one attachment mechanism for the different kinds of collagen based hard tissue in the rat molar region.