Osteotomia para implantes e a formação de danos no osso: influência da velocidade de fresagem e do tipo ósseo

Abstract

Purpose: To evaluate bone damage formation and the influence of speed protocols during implant site preparation in an ex vivo experimental study. Method: Six bone fragments (90x40 mm) extracted from two fresh bovine ribs were used to simulate implant drilling procedures using a sequence of three drills. A total of 18 implant site preparations were performed and 3 groups were designed according to the drilling speed: 1200 rpm (Group 12, n=6), 800 rpm (Group 8, n=6) and 400 rpm (Group 4, n=6). After the osteotomy procedure, the bone fragments were cut into eighteen blocks and were stained with xylenol, dehydrated and covered in methylmethacrylate. Two slides were obtained per block, one at the preparation site and one adjacent to it. Cortical and cancellous bone were evaluated under fluorescence and polarized light. Bone damage formation was evaluated with total bone area (B.Ar). Fracture density was assessed (Fr.D=N/mm2), along with microdamage morphology (linear or diffuse) and density (Cr.D=N/mm2). Two slides were used to assess the three-dimensional structure of linear microcracks by confocal microscopy. Results: There was a significant association with damage formation and the type of bone (p=0.0016), with more damage in cancellous than in cortical bone. Positive correlation between fracture and microdamage densities (p=0.05, r 0.54) was found. There was no difference among the three speed groups. Tridimensional visualization of the linear microcracks was helpful to distinguish the damage. Conclusion: Bone damage was generated after the drilling osteotomy procedure, including: microcracks, diffuse damage, fractures and the formation of bone chips. More damage formation was associated with cancellous than cortical bone. Different speeds of drilling were not relevant to increasing the formation of bone damage within the limits of this study.