[Effect of various implant materials on cementogenesis].

Various implant materials have been used to stimulate the regeneration of supporting bone lost from periodontal disease. In addition, the histologic features of bone regeneration associated with their implantation have been evaluated. Very little, however, seems to be known about the effect of implant materials on cementum formation. The aim of this study was to determine whether implant materials stimulate the cementogenesis on adjacent planed root surfaces. Twelve monkeys with healthy gingivae were used in this experiment. Following mucoperiosteal flap elevation, "windows" were chiseled in the bone to the proximal root dentin surfaces and adjacent root surfaces were planed. Each of the three implant materials [tricalcium phosphate (TCP), decalcified bone matrix (DBM) and hydroxyapatite (HA)] were then placed in the cuspid and incisor root "windows" before the flap was sutured back into the previous position. Windows with no implantation served as a control. Animals were sacrificed 2, 4 and 8 weeks postoperatively. Biopsy specimens including the tooth and surrounding bone were examined by light and electron microscopy. At 2 weeks, all implant particles were surrounded by fibrous tissue. On the other hand, fibrous tissues filled the control defect. On the planed root surfaces after the implantation of TCP and DBM, furthermore, cementoid tissue appeared. At 4 weeks, a considerable amount of new cementum was deposited on the root surfaces except in the implantation of HA. It was especially pronounced after implantation of TCP and DBM which promoted bone regeneration after resorption. These results suggest that resorbable implant materials such as TCP and DBM not only facilitate the formation of new bone, but also of new cementum.