The effectiveness of 10% chlorhexidine varnish treatment on dental caries incidence in adults with dry mouth

Objectives: This study compared a 10% chlorhexidine varnish treatment with placebo and sham treatments for preventing dental caries in adult patients with xerostomia (dry mouth). Design: The study was a multicentred, randomized, parallel group, double blind, placebo‐controlled clinical trial. Setting: All examinations and procedures were performed at Tuft's University, Boston, MA, the University of British Columbia, Vancouver, BC or the University of Western Ontario, London, ON. Subjects: Subjects were adults with recent or current dental caries experience, high salivary levels of cariogenic microorganisms and low salivary flow rates. Results: 236 subjects completed at least one post‐treatment examination. There were 697 new carious lesions diagnosed, 446 (64%) located on coronal surfaces and 251 (36%) located on root surfaces. The mean attack rate was 0.23 surfaces/100 surfaces at risk. A treatment difference observed between the Active and Placebo groups was statistically significant for root caries increment (p=.02) and total caries increment (p=.03). A treatment difference observed between the Active and Sham groups was not statistically significant for coronal, root or total caries increment. Analysis of variance of treatment group differences was performed using mutans streptococci counts, salivary flow rates, age, sex, caries prevalence, medications, time to first event and early withdrawal as co‐variables. These factors did not meaningfully alter the findings. Conclusions: The difference between the 10% chlorhexidine varnish and placebo treatments is considered to be highly clinically significant for root caries increment (41% reduction) and for total caries increment (25% reduction) but only for coronal caries increment (14%).