RESUMO
INTRODUCTION: In this study, we evaluated the effects of surface modifications of miniscrew implants (MSIs) and force application on bone surrounding MSIs. METHODS: Seven skeletally mature male foxhound dogs were followed for 9 weeks; a randomized split-mouth design was used to compare 21 MSIs with sandblasted, large-grit, and acid-etched (SLA) surfaces and 21 identical machine-surfaced MSIs. MSIs immediately loaded with 200-g nickel-titanium coil springs were compared with unloaded MSIs. Bone volume to total volume ratios of cortical and noncortical bone regions were measured at 6 to 24 µm and 24 to 42 µm from the entire MSI surface using microcomputed tomography with an isotropic resolution of 6 µm. RESULTS: Clinical success of SLA-surfaced MSIs was 100%, compared with 85.7% for machine-surfaced MSIs. There was significantly (P <0.05) more bone at the coronal aspects of the SLA-surfaced than the machine-surfaced MSIs; the SLA-surfaced MSIs also showed significantly greater decreases in bone between their most coronal and apical aspects. MSIs that were loaded demonstrated significantly (P <0.05) greater decreases in surrounding bone than unloaded MSIs. The amount of bone within 6 to 24 µm of the MSIs was significantly less than that within 24 to 42 µm. Mean placement torque was higher for the SLA-surfaced (42 Ncm) than the machine-surfaced (39 Ncm) MSIs, but the difference was not statistically significant. CONCLUSIONS: SLA surface treatment and loadings have significant effects on bone surrounding the MSIs; this might be related to higher success rates and greater secondary stability.