The fibrillar structure of cementum and dentin at the cemento-dentinal junction in rat molars

The cemento-dentinal junction was examined in demineralized rat molars with complete roots by scanning electron microscopy combined with NaOH macerati on. It is established that the NaOH maceration removes interfibrillar subst ances and cells from connective tissues selectively without structural dama ge to collagen fibrils, The cementum was detached from the dentin by the ma ceration. The inner cementum surface facing the dentin and the outer dentin surface facing the cementum were observed, In acellular cementum, both the outer dentin surface and the inner cementum surface had a smooth appearanc e, There was little indication of fibrils intermingling between dentin and cementum. Tn contrast, both the inner cementum surface and outer dentin sur face in cellular cementum had an uneven appearance due to the irregular arr angement of collagen fibrils. Point-like protrusions of fibril bundles were observed on both surfaces. Some (not all) of these point-like protrusions appeared to correspond to places of fibrillar intermingling between dentin and cementum.