Clinical decisions regarding the stability and osseointegration of mandibular implants positioned using the bone expansion techniques are conflicting and limited. The objective was to evaluate the stability of implants placed using 2 surgical techniques, selected according to the initial width of the mandibular posterior edentulous ridge, with D3 bone density, during a 12-week period. Fifty-eight implants in 33 patients were evaluated. Thirty-two implants in 24 patients were positioned using the osteotome expansion technique, and 26 fixtures in 17 patients were installed using the conventional drilling technique. The implant stability quotient values were recorded at weeks 0, 1, 2, 3, 4, 6, 8, 10, and 12 postsurgery and evaluated using analysis of variance, independent, and paired t tests. Calibrated according to the stability reading of a 3.3-mm diameter implant, the osteotome expansion group was associated with a lower bone density than the conventional group (64.96 ± 6.25 vs 68.98 ± 5.06, P = .011). The osteotome expansion group achieved a comparable primary stability (ISQb-0, P=.124) and greater increases in secondary stability (ISQb-12, P=.07) than did the conventional technique. A D3 quality ridge with mild horizontal deficiency is expandable by using the osteotome expansion technique. Although the 2 groups presented similar implant stability quotient readings during the study period, the osteotome expansion technique showed significant improvement in secondary stability. The healing patterns for these techniques are therefore inconsistent.