[Histological comparison of the effect of different implanted hydroxyapatites in the animal periodontium]

The effect of various types of synthetic hydroxyapatites (HA), coated or not with collagen or human plasmatic fibrin, has been studied after 3 month implantation either in freshly extracted alveoli in miniature pigs or in experimentally induced periodontal lesions in beagle dogs. The best histological results were observed in HA without organic coating. The Bioapatite consisting in crystals with a mean size of 146 nm +/- 47 nm were well integrated in the alveolar bone. Similar results were obtained with micro-sized hydroxyapatite, with a mean crystal size of 38 nm +/- 16 nm. But at 3 months, this HA type was still actively integrated in bone with osteogenesis. When these 2 types of HA were coated with collagen or plasmatic fibrin, they were less well incorporated in alveolar bone and were even able to develop localized and moderate inflammatory reactions. The main purpose of synthetic HA is to promote alveolar bone formation in periodontal lesions. For an improved tissular regeneration, it is recommended to use simultaneously in the future synthetic HA together with resorbable biocompatible synthetic membranes.