Atrophic maxillary floor augmentation by mineralized human bone allograft in sinuses of different size: an histologic and histomorphometric analysis.

OBJECTIVE: The aims of this work were to histologically examine the healing of mineralized human bone allograft (MHBA) in sinus augmentation for elevating a severe maxillary atrophy ridge (≤2 mm residual ridge height) and to correlate the results to the sinus cavity size.

MATERIAL AND METHODS: A two-stage protocol was conducted in 23 patients, all having crestal bone ≤2 mm. A mixture of 80/20 cortical/cancellous of MHBA particles was used to augment sinus using the lateral window approach in narrow (NS; <15 mm bucco-palatal distance) and wide (WS; ≥15 mm bucco-palatal distance) sinuses, based upon computerized tomography (CT) assessment. A bone core biopsy was taken at implant placement, 6 and 9 months after surgery. Microradiography, histology and histochemistry of methacrylate-embedded sections were performed to analyze and to evaluate the bone and graft amount.

RESULTS: Newly formed bone around MBHA particles was found in all 28 biopsies. Bone showed a woven structure at 6 months after surgery and a lamellar structure 9 months after surgery. At 6 months after surgery, the 13 NS and 15 WS had 30.5±8.8% and 20.7±4.9% mean±SD bone formation, respectively. At 9 months after surgery, it was 38.8±7% (NS) and 30.7±3% (WS). Residual graft was about 16% (6 months) and 6% (9 months), in both NS and WS. The Mann-Whitney test showed a greater bone formation in NS than in WS (P<0.005).

CONCLUSIONS: The used 80/20 MHBA mixture appears to promote, in the severe atrophic maxilla, a satisfactory bone formation. Our results prove that the larger the sinus, the longer the maturation time needed to achieve a suitable amount of new bone formation.