Eighteen-month radiographic and histologic evaluation of sinus grafting with anorganic bovine bone in the chimpanzee

Maxillary sinus grafting procedures are currently the treatment of choice w hen the alveolar crest of the posterior maxilla is in close approximation t o the maxillary sinus. The short-term histologic and radiographic healing f ollowing sinus grafting with natural bone mineral (Bio-Oss) in the chimpanz ee has been evaluated. We have previously shown by histomorphometric and ra diographic analysis that the percentage of vital bone area, the vertical he ight, and the density of new bone in the maxillary sinus was significantly greater with anorganic bovine bone compared to bovine Type I collagen matri x. The purpose of this in vivo study was to determine the bone mineral dens ity (BMD) of the sinus grafts, the vertical height stability, the vital bon e area, and the extent of anorganic bovine bone replacement 18 months posto peratively in 4 maxillary sinuses from 4 different animals. Radiographic an alysis of computed tomographic scans taken at 1.5 years revealed an average BMD of 658 mg/mL, which was not significantly different from the values fo und at 6.5 months. The radiographic vertical height was maintained between the 6.5- and 18-month time points. On average, the grafts were found to hav e a height of 14 mm. Lateral wall biopsy specimens at 7.5 months were compa red to those at 18 months. With the anorganic bovine bone treatment, the pe rcentage of vital bone area increased from 62 +/- 3% to 70 +/- 7% and the p ercentage of natural bone mineral area decreased from 19 +/- 14% to 6 +/- 3 %. The bovine Type I collagen matrix vital bone percentage at 7.5 months wa s 34 +/-:21%. These results demonstrate that sinus grafting with anorganic bovine bone maintains radiographic evidence of density and height stability to 1.5 years. In addition, histologic evidence supports the hypothesis tha t anorganic bovine bone is replaced by vital bone.