Bioabsorbable materials for guided bone regeneration prior to implant placement and 7-year follow-up: report of 14 cases.

The purpose of the present study was to evaluate the efficacy of a guided bone regeneration (GBR) procedure prior to implant placement and the long-term outcome of the inserted implants. Prior to dental implant placement, GBR procedure was performed on 14 patients (mean age 48 years) using a synthetic hydroxyapatite (HA) spacer under a collagen membrane. After a mean healing period of 8 months, bone biopsies were obtained during the placement of 14 implants. The specimens were processed for histology without demineralization in order to assess bone quality and quantity of the regenerated bone. Both the bone density and the resorption degree of HA particles were relatively varied between samples. The different phenotypes of osteoclasts and multinucleated giant cells and the individual host response could partially explain the unpredictable results in terms of bone remodeling and biomaterial resorption. However, the presence of HA particles in the regenerated bone had no influence on the osseointegration of implants presenting a success rate of 86% after a 7-year observation period. These results confirm the possibility of regenerating bone by means of bioabsorbable materials, assuring at the same time the long-term success for implants inserted in regenerated sites.