Vitality of Retromolar Bone Grafts - A Critical Appraisal of the Current Histomorphometric Approach

N9MUI ORAL COMMUNICATION CLINICAL RESEARCH – SURGERY

Background: It is assumed that empty osteocytes lacunae in augmented autologous bone blocks indicate necrotic bone.

Aim/Hypothesis: The present study appraises critically the current histomorphometric approach by comparing bone block biopsies prior grafting and after healing of the same patients.

Materials and Methods: 25 Patients underwent autologous bone grafting in the maxilla and mandible. Intraoral bone blocks were harvested from the retromolar area in local anesthesia. Prior to grafting a biopsy (control) was retrieved from the graft with a trephine bur. The blocks were fixated and after three months of healing a second biopsy was retrieved from the integrated bone graft at the time of implant placement from the same patient. The control and grafted biopsies were compared histomorphometrically using Pararos-Anilin Azur II staining using the following parameter: Osteocyte lacunae (amount of empty/filled lacunae), number of Haversian canals and originating new bone formation.

Results: The bone grafting procedure was successful in all patients, no dehiscences occured. The control biopsies demonstrated the same ratio of filled/empty osteocytes lacunae (P = 0.136) and number of Haversian canals (P = 0.51) in comparison to bone grafts after three months of grafting. No inflammatory cells were detectable in all biopsies after grafting. The Pararos-Anilin Azur II staining revealed new bone formation around all Haversian canals in the second biopsies.

Conclusions and Clinical Implications: The results suggest that empty osteocyte lacunae are not a reliable predictor for bone graft vitality since the same amount was found in the bone retrieved form the donor site and in the graft after a three-months healing period. Different parameters should be considered when describing the vitality of an intraoral retromolar bone graft among which the new bone formation around the Haversian Canal seems promising to investigate in further studies.

Keywords: Bone Graft, Retromolar, Vitality, osteocyte lacunae, Histomorphometric Analysis.