Objective: To report and evaluate ultrasonic bone surgery (USBS), also known as piezosurgery, in split-crest procedures with immediate implant placement at 3 years of follow-up. Method and Materials: Sixty-one split-crest procedures were performed, and 180 implants were placed in 43 patients. Initial ridge width varied between 1.5 and 5.0 mm (mean 3.3 ± 0.7 mm). Bone density was type I (11.1%), type II (27.8%), type III (28.9%), and type IV (32.2%). The USBS device worked with a 20 to 32 kHz vibrating frequency and 90 W peak power. Results: Mean split length was 14.8 ± 10.8 mm; mean final ridge width was 6.0 ± 0.4 mm. At second-stage surgery, five of 180 implants failed to osseointegrate (2.8%), all in the maxilla. Also at second-stage surgery, the success rate of the implants placed simultaneously to the split crest performed with USBS was 97.2% overall, 95.1% in the maxilla and 100% in the mandible. No loaded implant failed during the 3-year followup; respective success rates were unchanged. Conclusions: USBS is predictable to perform split-crest procedures, without risk of bone thermonecrosis; it decreases the risk of soft tissue alteration. Bone-cutting efficiency was satisfactory with the present USBS device because of its elevated ultrasonic vibrating power, especially in soft type IV bone. Keywords: Bio-Oss, bone density, dental implants, piezosurgery, PRP, split-crest, ultrasonic bone surgery