ObjectivesTo evaluate the influence of instrumentation technique on the early osseointegration histomorphometrics and biomechanical fixation of fully laser-etched microgrooves implant surfaces in a sheep model. Material and MethodsSix sheep were subjected to bilateral hip surgeries 3 and 6weeks before euthanasia. A total of 48 implants (empty set4.5mm, 8mm in length) were distributed among four sites (8 per animal) and placed in bone sites drilled to 4.6mm (reamer), 4.1mm (loose), 3.7mm (medium) and 3.2mm (tight) in diameter. After healing, the animals were euthanized and half of the implants were biomechanically tested, while the remainder was subjected to non-decalcified histologic processing. The histomorphometric parameters assessed were bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). Statistical analysis was performed using a mixed-model analysis of variance with significance level set at P<0.05. ResultsA general increasing trend is present from 3 to 6weeks for most of the variables. The groups prepared to be press fit seemed to present higher values, which were maintained throughout the observation period. The reamer group presented the lowest BIC probably due to the drilling technique; however qualitatively, more new bone seemed to be in contact to the implant surface, at 3weeks, whereas the implants placed in press-fit situations were mainly supported by cortical bone. ConclusionThe laser-etched microgrooved implant presented osteoconductive and biocompatible properties for all surgical procedures tested. However, procedures providing increasingly higher press-fit scenarios presented the strongest histomorphometric and biomechanical responses at 3 and 6 weeks.