The purpose of this study was to determine the effectiveness of an antibiotic rinse preparation, containing metronidazole and nystatin, in decreasing oral malodor and periodontal disease for individuals whose chief complaint was halitosis. This topical approach to oral biofilm control, by proactively managing the most pathogenic bacteria, differs from the traditional approach of reactively treating the symptoms by attempting to reduce all oral bacteria. The late Dr. Loesche, University of Michigan, School of Dentistry, had previously described these different paradigms as the specific plaque hypothesis and the non-specific plaque hypothesis, respectively. Patients in this study were measured before and after treatment for volatile sulphur compounds using a portable sulphide monitor, a digital gas chromatograph, and organoleptic assessment. The presence of periodontal disease was determined by 6-point periodontal probing, to assess pocket depth and bleeding points. Of the 1000 patient charts sent electronically to the University of Michigan for analysis, 649 participants were selected based on complete pre- and post-treatment data, and statistically analyzed by a statistician, who was an expert in case study analysis. The post-treatment reduction of oral malodor was 80% (P = 0.0001). The difference in bleeding points pre- and post-treatment was 87% (P = 0.0001). There was a decrease in the number of teeth with 6 and 7 mm pockets by 76% and teeth with 5 mm pockets decreased by 84% (P = 0.0001). Treatment with the antibiotic rinse had a positive change in the periodontal status and breath odor of these patients. These data indicate that there is considerable advantage to the use of topical antibiotic rinses. A substantial decrease in both halitosis and periodontal disease markers can be achieved without the risk of the systemic effects of an oral antibiotic.