A 12-MONTH CLINICAL TRIAL WAS CONDUCTED to compare the effectiveness of a prebrushing rinse (PBR) in plaque removal with that of water. Four groups participated in the study; group 1 (test group) rinsed with PBR before brushing; group 2 rinsed with plain tap water; group 3 brushed only; and group 4 rinsed with sterile water (same color as the PBR). Pre-brushing and post-brushing plaque scores were recorded at baseline, 3 months, 6 months, 9 months (Ramjford surfaces) and 12 months for groups 1, 2, and 3 and at baseline, 3 months and 6 months for group 4. Pre-brushing minus post-brushing plaque scores (decrements) were significantly higher in the PBR group at baseline, and 6, 9, and 12 months. Using a single criterion (gingival bleeding index) there were no differences between the 4 groups at any of the 5 assessments, hence, the clinical significance of the higher plaque removal scores in the PBR group remains in doubt.