Effect of chlorhexidine-thymol varnish on caries lesion development in first permanent molars.

OBJECTIVE: The aim of this study was to investigate the caries prevention efficacy of chlorhexidine-thymol (CHX-T) varnish on newly erupted permanent first molars. METHODS: Fifty-seven six- to eight-year-old school children were included in a program of sequential CHX-T varnish application. For inclusion, they had to have at least two homologous, newly erupted first permanent molars with visually sound occlusal surfaces. A clinical examination was used to determine the molar eruption stage, biofilm presence, and whole caries status. There were 99 pairs of molars in the study population. A split-mouth design was used where each child randomly had one first molar treated with six applications of CHX-T varnish, and the other with a placebo varnish, every 15 days for 75 days. The children were then revaluated for caries one year following the conclusion of treatment. RESULTS: Fourteen pairs of teeth presented incipient enamel caries lesions in both molars (one CHX-T and one placebo varnish), four developed lesions in the placebo-treated molars only, and eight developed lesions in CHX-T varnish-treated molar only. No significant statistical differences were found between the two groups with regard to caries increment (p = 0.20). CONCLUSION: Six applications of CHX-T varnish had no protective effect against caries development.