The effects of using water flosser versus interdental brush on gingival health in patients with mandibular bonded retainer - a randomized controlled trial

AIM: Effective interdental cleaning is essential for maintaining periodontal health in patients with fixed orthodontic retainers. This study compared the efficacy of a water flosser and an interdental brush in improving periodontal health over six months. METHODS: Seventy participants were randomized into water flosser (n = 35) and interdental brush (n = 35) groups. Periodontal indices including plaque index (PI), gingival index (GI), bleeding index (BI), calculus index (CI), clinical attachment level (CAL), probing depth (PD), and marginal recession (MR) were assessed at baseline (T0), three months (T1), and six months (T2). Mann-Whitney U tests compared groups at each time point. Repeated measures ANOVA evaluated time, group, and interaction effects. Generalized estimating equations (GEE) determined the influence of demographic and clinical variables on outcomes. RESULTS: At baseline, no significant differences were found between groups (p > 0.05). By T1 and T2, the water flosser group showed significantly lower PI, GI, CI (p < 0.001). Significant time × group interactions favored the water flosser for these parameters, while CAL and PD showed no significant between-group differences. Generalized estimating equation (GEE) revealed superior soft-tissue outcomes with water flossers and identified male gender and thin gingival biotype as predictors of poorer periodontal outcomes. CONCLUSION: Water flossers offer superior improvement in soft-tissue periodontal indices compared to interdental brushes in fixed retainer patients. Age did not influence periodontal outcomes, while male gender was associated with higher plaque and gingival inflammation scores. TRIAL REGISTRATION: ClinicalTrial.Gov; Registration number: NCT07054203; June 25, 2025.