Histology of human alveolar bone regeneration with a porous tricalcium phosphate - A report of two cases

Porous P-phase tricalcium phosphate particles (pTCP) (Cerasorb (R)) were used in two patients to restore or augment alveolar bone prior to the placement of dental implants. In one patient, pTCP was used to fill a large alveolar defect in the posterior mandible after the removal of a residual cyst, and in another patient to augment the sinus floor. Biopsies were taken at the time of implant placement, 9.5 and 8 months after grafting, respectively, and processed for hard tissue histology. Goldner-stained histological sections showed considerable replacement of the bone substitute by bone and bone marrow. In the 9.5 months biopsy of the mandible, 34% of the biopsy consisted of mineralised bone tissue and 29% of remaining pTCP, while the biopsy at 8 months after sinus floor augmentation consisted of 20% mineralised bone and 44% remaining pTCP. Bone and osteoid were lying in close contact with the remaining pTCP and were also seen within the micropores of the grafted particles. Tartrate resistant-acid phosphatase (TRAP) multinuclear cells, presumably osteoclasts, were found surrounding, within and in close contact with the pTCP particles, suggesting active resorption of the bone substitute. Remodelling of immature woven bone into mature lamellar bone was also found. No histological signs of inflammation were detected. The limited data presented from these two cases suggest that this graft material, possibly by virtue of its porosity and chemical nature, may be a suitable bone substitute that can biodegrade and be replaced by new mineralising bone tissue.