The purposes of this prospective, randomized, controlled clinical investigation were to evaluate the performance of motorized ridge expanders (MREs) and to compare their results with those achieved using lateral ridge augmentation (LRA). Eight subjects with bilateral ridge deformities were selected. One technique was used on the right side and the other on the left. Implants were placed 6 months after bone augmentation procedures. All measurements were recorded at 2 and 5 mm from the most coronal aspect of the crest. The augmentation achieved with both techniques was statistically significant: 1.2 mm for LRA and 1.5 mm for MRE 2 mm from the crest and 1.5 mm for LRA and 1.6 mm for MRE at 5 mm from the crest. The differences between the two techniques were statistically insignificant. The amount of expansion achieved in the MRE sites appeared to be negatively correlated with the thickness of the cancellous bone (P .05), and it was not affected by the thickness of the cortical plate. The MRE technique appears to be as effective as the LRA technique in augmenting the thickness of atrophic ridges. Defects treated with MREs showed less bone width contraction during the first 6 months of healing.