The goal of this multicenter randomized controlled study was to evaluate the effectiveness of a newly developed ionic-sonic electric toothbrush in terms of plaque removal and reduction of gingival inflammation. A total of 78 subjects from three dental centers were invited to join the study. They were randomized to receive either a manual toothbrush (control group) or an ionic-sonic electric brush (test group). Full-mouth prophylaxis and oral hygiene instructions based on the stationary bristle technique were provided 1 week prior to the baseline visit. At baseline and at each follow-up appointment, Plaque Index (PI) and Gingival Index (GI) were recorded. In addition, probing depth (PD) and bleeding on probing were recorded at baseline and at the last appointment (week 5). At completion of the study, subjects in the test group were given a questionnaire regarding their satisfaction with the toothbrush. Sixty-four subjects completed the study (control: 28; test: 36). The mean age of the subjects was 36.90 ± 12.19 years. No significant difference between the baseline and 5-week PD was found. Plaque removal efficacy and reduction in gingival inflammation were more significant for the test group at week 2. Both the control and test groups showed statistically significant improvement in PI and GI from baseline to week 5. The ionic-sonic toothbrush was more effective than manual toothbrush after a 1-week application.