Influência da osseodensificação e da macrogeometria dos implantes na estabilidade primária e na microarquitetura óssea peri-implantar: estudo experimental

Abstract

Primary stability is a crucial factor for successful osseointegration and is influenced by bone density, drilling protocol, and implant macrogeometry. In lowdensity bone, osseodensification has emerged as an alternative technique to optimize initial mechanical stability by promoting lateral bone condensation and apical compaction. This experimental study aimed to evaluate the influence of implant macrogeometry (Epikut – E versus Strong SW – SW, SIN Implant System), associated with the osseodensification technique, on primary stability and peri-implant bone microarchitecture. Forty implants were placed in ten porcine tibiae under ex vivo conditions using the epiphyseal region. Osteotomies were prepared using Densah® burs according to the osseodensification protocol. Subsequently, twenty implants of each macrogeometry were inserted in a standardized and balanced distribution between the superior and inferior portions of the tibial plateau. Primary stability was assessed by insertion torque and resonance frequency analysis (implant stability quotient, ISQ) by a single calibrated operator. Bone cores containing the implants were then harvested using a trephine bur and stored in 70% ethanol for micro-computed tomography (micro-CT) analysis (13-µm isotropic voxel size). Additional core bone samples collected away from the implant sites were used as the control group. After the microarchitectural analysis, three specimens from each group were randomly selected, embedded in methyl methacrylate, previously labeled with Xylenol Orange, and evaluated by fluorescence microscopy. The results demonstrated no statistically significant differences between implant macrogeometries regarding insertion torque or ISQ values. Micro-CT analysis revealed that, when associated with osseodensification, the Epikut group exhibited greater trabecular thickness, whereas the Strong SW group showed a lower trabecular number and greater trabecular separation compared with the control group. No significant differences were observed between the two implant macrogeometries. Digital insertion torque showed a positive correlation with bone volume fraction and trabecular thickness. Qualitative peri-implant tissue analysis demonstrated areas of increased bone condensation and morphological patterns consistent with trabecular compaction and reorganization, corroborating the quantitative findings obtained by micro-CT. Regions corresponding to the epiphyseal endochondral ossification zone were also identified, leading to the exclusion of these specimens from the statistical analysis because the cartilage areas would interfere with the peri-implant volume of interest used for microarchitectural evaluation. It was concluded that implant macrogeometry, when associated with the osseodensification technique, did not significantly influence primary stability under the experimental conditions evaluated. Conversely, osseodensification promoted changes in the peri-implant bone microarchitecture consistent with trabecular compaction and reorganization, providing a biomechanically more favorable environment for initial implant stability. These findings suggest that the modifications induced by the osteotomy preparation technique exert an influence on the initial biomechanical behavior than the differences in implant macrogeometry evaluated in this study.