Fate of a Bovine-Derived Xenograft in Maxillary Sinus Floor Elevation After 14 Years: Histologic and Radiologic Analysis

This report assesses the results following sinus floor augmentation performed 14 years previously in which bovine bone xenograft material was used without implant insertion. After sinus floor augmentation, using a 20:80 mixture of autogenous bone and inorganic bovine bone material (Bio-Oss), bone biopsy specimens were taken from the grafted site, processed with Donath's sawing and grinding technique, stained with toluidine blue, and mounted on high-sensitivity plates for histology and microradiography. Histologic and microradiographic analysis showed the ingrowth of newly formed bone into the graft with interspersed residual Bio-Oss granules. The percentage of Bio- Oss and newly formed bone was 10.18% and 9.32%, respectively, within a total surface area of 70.61 mm2 at the site of the corresponding missing first molar, and the percentage of Bio-Oss and newly formed bone was 11.47% and 14.96%, respectively, within a total surface area of 63.92 mm2 at the corresponding missing second molar. The newly formed bone was vital without signs of resorption. This study produced strong evidence that newly formed bone was distributed throughout the bone substitute material around all of its granules and that the grafted site consisted of vital bone even in its central parts. The differences in degradation rate and/or whether the effect of bone graft substitutes alone and/ or in combination with other types, shapes, and sizes of graft materials needs further clinical investigation, especially in regard to long-term changes.