Microtomographic and histomorphometric evaluation of the effectiveness of the bovine-derived xenograft (In700) and the alloplastic beta-tricalcium phosphate (B-TCP) compared to Bio-OssTM in sinus floor augmentation

Abstract

Maxillary sinus floor augmentation is a common procedure to increase bone volume in the atrophic posterior maxilla, allow for proper metallic implant placement. This procedure is reliable and known to be effective with the use of biomaterials alone. However, the biomaterials with proven efficacy in the literature are imported and its use increases the costs of the procedures, hindering the access of the population. The objective of this study is to compare bone formation, resorption rate, osteoconductivity, and three-dimensional volume changes of two new materials under development in the Brazilian laboratory, the bovine-derived xenograft (In 700) and the alloplastic B-tricalcium phosphate (B-TCP) versus the established xenograft. Bio-Oss®. Bilateral sinus floor augmentation procedures will be performed in 27 rabbits (a total of 54 maxillary sinuses). Each maxillary sinus was randomly assigned to 0.2-mL of one of the bone substitute Bio-Oss, In700 or B-TCP homogeinated with blood. On each bone window access will be placed a cortical bone membrane resorbable bovine (Gen-Derm®). After 2-weeks (n = 9), 4-weeks (n = 9) and 8-weeks (n=9) healing period, the sinus region will be collected and fixed in 10% formalin in phosphate buffer for one week. The sinuses will be analyzed by micro-computed tomography to determine the total augmented volume and the volume occupied by biomaterial and newly formed bone in each sinus. Subsequently, the samples will be demineralized and submitted to histological processing. Semi-sections cuts of 5-mm-thick will be obtained and stained with hematoxylin-eosin. The cellular and tissue events triggered by each material during the process of bone repair will be evaluated by histomorphometric analysis. In addition, the microstructural characterization of each material by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) will be realized in 5 samples of each material. The results of these experiments will relate the microstructural characteristics of biomaterials such as, presence, size and interconnectivity of pores and chemical elements present at the surface of biomaterials with the pattern of bone formation in maxillary sinus. The results may propose or not the clinical applicability of these national biomaterials in maxillary sinus lift procedures. (AU)