MECHANISM OF IRRIGATION EFFECTS ON GINGIVITIS

ALTHOUGH GINGIVITIS IS INITIATED by plaque and plaque removal controls gingivitis, gingival irrigation with water has been shown to reduce g ingivitis without reducing plaque. This study attempted to explore pos sible mechanisms involved in the treatment of gingivitis by water irri gation. Patients (n = 125) with more than 20 teeth, less than 4 sites with probing depth (PD) deeper than 6 mm, bleeding on probing (BOP) fr equency of 30% or higher, and no systemic disease were randomized to o ne of four treatment groups: toothbrushing alone (brush), toothbrushin g plus chlorhexidine 0.12% rinse 2x/day (CHX), toothbrushing plus wate r irrigation 1x/day (irr+H2O), or toothbrushing plus chlorhexidine 0.0 4% irrigation 1x/day (irr+CHX). Six sites/tooth were examined at basel ine, and at 3 and 6 months for BOP and PD using an automated probe, an d for gingival index (GI) and plaque index (PI) by standard means. A p rophylaxis and oral hygiene instructions were provided after baseline and 6 month measurements. Subgingival microbial samples and crevicular fluid (GCF) were collected from 2 teeth/subject at each time point. M icrobial samples were processed for anaerobic culture and the predomin ant cultivable flora was determined. CHX and irr+CHX had a 30 to 35% d ecrease in mean PI, while brush and irr+H2O had only a 12 to 16% decre ase. BOP was reduced by 14% in the brush group and 23 to 24% in the ot her groups. GI was significantly correlated with PI in the brush, CHX, and irr+CHX groups, but not in the irr+H2O group. Prevotella intermed ia was significantly reduced in both irrigation groups, but not CHX or brush groups. Comprehensive analysis of selected components of the gi ngival crevice fluid is in progress and will be reported in the future . The current findings indicate that the mechanism of gingivitis reduc tion by water irrigation is not related to plaque reduction but may in volve specific host-microbiota alterations in the subgingival environm ent.