The influence of the bucco-palatal distance on sinus augmentation outcomes.

BACKGROUND Maxillary sinus augmentation is one of the most reliable implant site development options to increase vertical bone height. However, graft consolidation requires adequate angiogenesis and migration of cells involved in osteogenesis and bone remodeling. It is speculated that these biologic events are greatly determined by the dimensions of the maxillary sinus cavity. Hence, the purpose of this study is to assess the influence of the distance from the lateral to the medial wall of the maxillary sinus on the outcomes of sinus augmentation procedures. METHODS A total of 25 patients in need of sinus augmentation were recruited for the study. After initial examination, customized radiographic and surgical guides were fabricated and a cone-beam computerized tomography scan was obtained per patient. The bucco-palatal distance (BPD) was measured at 8, 10, and 12 mm from the alveolar crest. Sinus grafting was performed by a lateral window approach using a particulated allograft material. Patients were followed-up for 6 months. At the time of implant placement, bone core biopsies were harvested using the radiographic-surgical guide. Sections of the bone cores at 8, 10, and 12 mm from the alveolar crest were histomorphometrically analyzed. The proportion of vital bone (%VB) was correlated with the BPD using a statistical model. RESULTS Twenty-one patients underwent sinus augmentation for a total of 24 sinuses; however, the data analyzed contained only one sinus per patient. One sinus developed an infection after grafting, resulting in a 96% success rate for the sinus grafting procedure. Twenty sinuses were used in the final statistical analysis. Histomorphometric analysis revealed that mean %VB was 22.71 +/- 19.08, mean percent of remaining allograft was 23.39 +/- 20.85, and average percent of non-mineralized connective tissue was 53.90 +/- 13.23. Analysis of the correlation between %VB and BPD by linear regression, using the actual values of BPD showed a strong negative association (R(2) = 0.141; P <0.001). CONCLUSION The findings suggest that the %VB formation after maxillary sinus augmentation is inversely proportional to the sinus BPD.