Quality of periodontal healing. II: Dynamics of reparative cementum formation

The purpose of the present study was to follow the formation of mineralised tissue (reparative cementum) on instrumented root surfaces. Twenty-four permanent maxillary and mandibular laterals from six, 3-4-year-old monkeys (macaca fascicularis) were used in the experiment. The incisors were gently extracted and the periodontal membrane (PDM) and cementum on the mesial surface of the roots removed to a distance of 1-2 mm from both the cemento-enamel junctions and the apices of the roots. The teeth were subsequently replanted. Ankylosis was seen both after 3 and 5 wks, although to a lesser degree at 5 wks to be virtually absent at 10 wks. It appeared that the resorptive activity predominant at 5 wks had removed the ankylotic fusion. After 10 weeks, a remaining layer of mineralised tissue, commonly referred to as reparative cementum was seen to cover the denuded dentine surfaces in the present study. It appeared not to be firmly attached to the root surface and did not show a normal cementum-morphology in polarised light. It had a multi-layered appearance resembling alveolar bone tissue and the connective tissue fibres adjacent to the reparative mineralised tissue-layer were not functionally oriented but rather parallel to the root surface. It was concluded that the formation of this mineralised tissue (rearative cementum) was the result of a transient ankylosis.