Estudo do reparo de defeito ósseo não crítico após a implantação de grânulos de wollastonita e fosfato tricálcico

Abstract

Introduction: In recent years, composites based on wollastonite (W) and beta-tricalcium phosphate (β-TCP) have been developed and evaluated for their potential to promote bone regeneration due to their biocompatibility, bioactivity, osteoconductivity, and biodegradability. Objective: To evaluate, in vivo, the osteogenic potential of W/β-TCP composite granules in two proportions, in a non-critical bone defect. Materials and Methods: Thirty male Wistar rats weighing between 300 and 350 grams were assigned to three experimental groups to produce a 5-mm-diameter bone defect in the center of each animal’s calvaria: 60W/40T – non-critical bone defect filled with W/β-TCP granules at proportions of 60% and 40%, respectively; 80W/20T – non-critical bone defect filled with W/β-TCP granules at proportions of 80% and 20%, respectively; and CG (control group) – non-critical bone defect without biomaterial implantation. Biological endpoints were established at 45 and 120 days. Histological sections stained with hematoxylin and eosin (HE) and picrosirius red (PSR) underwent a histomorphological evaluation for the following parameters: bone neoformation, biomaterial characteristics (appearance, arrangement, and presentation of the granules), inflammatory response, angiogenesis, and connective tissue (CT) formation. Osteogenic potential was determined histomorphometrically based on the rate of bone neoformation. Results: At 45 days, the histomorphological analysis revealed discrete centripetal bone neoformation in the 60W/40T and 80W/20T groups, whereas in the CG, the findings were more pronounced, although with reduced thickness compared to the height of the bone margins. At 120 days, bone formation was similar to the previous biological endpoint but more evident in the 80W/20T and CG groups. At both time points, the biomaterial granules were distributed throughout the defect area, surrounded by CT rich in blood vessels. This tissue exhibited a marked chronic granulomatous inflammatory infiltrate containing multinucleated giant cells (MGCs), particularly adjacent to the granules. In the CG, the residual area was filled with fibrous CT without inflammatory cells. The histomorphometric analysis at 45 days showed slight bone neoformation in the 80W/20T (6%) and 60W/40T (4%) groups, and a more marked response in the CG (22%). At 120 days, bone neoformation was more evident in the 80W/20T group (46%) compared to the 60W/40T group (22%). In the CG, the bone neoformation rate reached 49% at this biological endpoint, but the new bone was thinner than the margin. Conclusion: Granules containing 80% W and 20% β-TCP demonstrated higher osteogenic potential than those with 60% W and 40% β-TCP. Moreover, the biomaterials were biocompatible, bioactive, and osteoconductive.