Reconstruction of alveolar bone defect by calcium phosphate compounds

Osteoconductivity of newly developed calcium phosphate cements (CP-1, CP-2) was estimated in mandibular periapical alveolar bone of rats. The powder phase of CP-1 was an equimolar mixture of tetracalcium phosphate and dicalcium phosphate dihydrate, and that of CP-2 was alpha-tricalcium phosphate. The liquid phase of CP-1 and CP-2 was a solution containing tannic acid and citric acid. CP-1, CP-2, an apatitic sealer (ARS), or a zinc oxide eugenol sealer (ZOE) was respectively applied in the mechanically injured periapical regions through the root canals of both mandibular first molars of 15 rats. A further 15 rats were used as controls with no material in the region. The results of histopathological examination at 1, 3, and 5 weeks after operation were analyzed by the chi(2) test (95% confidence level). At 1 week, foreign-body giant cells were observed around CP-1 and CP-2, but not around ARS or ZOE. Congestion of small blood vessels was seen in bone defect areas of the controls. After 5 weeks, statistically significant bone reconstruction was induced by application of CP-1 (80.0%), CP-2 (90.0%) compared with ARS (33.3%). Fibrous scaring was seen in the controls. It is concluded that resolvability of CP-1 and CP-2 should contribute to osseous healing.