Methods: The efficacy against microorganisms was evaluated by calculating the inhibition zones as radii caused by specimens coated with varnish samples and put onto agar plate cultures of Streptococcus mutans (S.m.), S. sobrinus (S.s.), Lactobacilli, Actinomyces naes-lundii (A.n.), Candida albicans (C.a.). CHXdA and thymol release in an in-vitro model was simultaneously determined by measuring the absorbance at 255nm and 275nm. Reduction of the fluid flow trough dentine disks was studied in an in-vitro model according to Pashley.
Results: After application of the varnish the concentration of the antimicrobial components is increased due to solvent evaporation up to 10.5% (CP) and 8.3% (C). Both varnishes are acting antimicrobially by contact inhibition. No growth of bacteria could be observed beneath the coated specimens for both varnishes. Inhibition zone radii could be found for CP on cul-tures of S.m. (1.6mm) and S.s. (2.0mm), for C only on S.s. (<0.5mm). Whilst there is no sig-nificant difference in thymol release for CP and C, the release of CHXdA follows a more con-trolled sustained release pattern for CP than for C. After application on dentine specimens the fluid flow through dentine tubules was decisively reduced by both varnishes without any difference.
Conclusion: The new varnish (CP) provides better antimicrobial properties and better adhesion even when applied to wet tooth surfaces as it is more water tolerant than the predecessor product C. A clear reduction of the in-vitro fluid flow through dentine proves the desensitizing potential of both varnishes.