The purpose of this study was to evaluate the effectiveness of an ultrasonic toothbrush to reduce plaque and gingival inflammation when compared to a manual toothbrush. 62 healthy adult patients with a plaque index of at least 2.0, a 50% bleeding index and at least 16 natural teeth participated in this study. 31 patients were randomly assigned to the manual toothbrush group (group A) and 31 were assigned to an ultrasonic toothbrush group (group B). The Turesky et al. plaque index (PI), Eastman bleeding index, and Loe & Silness gingival index (GI) were performed at baseline, 15, and 30 days at the beginning of each appointment (pre-brushing). Patients then brushed with their assigned toothbrush and a post-brushing plaque index was recorded. Kruskal-Wallis one-way analysis of variance (ANOVA) was performed to determine between group differences on the parameters of all clinical indices. Results of the pre-brushing plaque index in group B were significantly lower at 15 and 30 days compared to group A. The post-brushing plaque index demonstrated no statistically significant between or within group differences. Both groups demonstrated significant within group reductions in GI and BI from baseline to 15 days and from 15 to 30 days, however, no between group differences were noted. The results of this study support the ability of an ultrasonic toothbrush to significantly remove plaque and reduce inflammation as well as a manual toothbrush over a 30 day period.