Effect of a 40% chlorhexidine varnish on demineralization of dentin surfaces in situ.

PURPOSE: To evaluate the effect of varnish with different chlorhexidine concentrations on the demineralization of dentin surfaces in situ. METHODS: An intraoral model was used to study the ability of chlorhexidine to prevent demineralization. Dentin specimens from extracted human teeth were treated with chlorhexidine varnish and exposed to the oral environment of 47 subjects. The dentin specimens were prepared from the cervical regions of 47 third molars, sterilized by irradiation with 60 GY and mounted in intraoral appliances worn by the subjects. Before the delivery of the appliance, the specimens and participants were treated once with one of the three different varnishes (according to the manufacturer's instructions). All participants were randomly assigned to one of the three groups: (1) EC 40 (n=16), (2) Cervitec (n=15), or (3) ChemFil Varnish (control group, n=16). The appliances were worn day and night for 3 weeks. At mealtimes, the appliance was stored in 10% sucrose solution. After exposure to demineralization, the dentin surface was evaluated by microradiography to assess the depth of the lesion (microm) and the loss of mineral (Vol% microm). Data analysis was accomplished using one-way ANOVA plus LSD testing (P< 0.05). RESULTS: Both chlorhexidine varnishes EC 40 and Cervitec resulted in significantly decreased mineral loss and lesion depth in dentin than the control. In addition, EC 40 treated specimens demonstrated significantly reduced lesion depth compared to Cervitec and the control (109.22 microm vs. 139.23 microm and 178.21 microm).

Demineralization effects of 2 bleaching procedures on enamel surfaces with and without post-treatment fluoride application.

In this in vitro study, the demineralization effect of 2 different bleaching procedures on enamel surfaces with and without the post-treatment application of fluoride was determined. Bovine enamel specimens (n= 180) were ground flat, polished and divided into 6 groups. Group A (n=30) specimens were bleached with Opalescence, 10% carbamide peroxide (Ultradent Products, Inc) for 8 hours daily for 2 weeks; Group B (n=30) specimens were treated with Whitestrips, 5.3% hydrogen peroxide (Procter & Gamble) for 1 hour daily for 2 weeks; Group C (n=30): the same as Group A, but after bleaching, a fluoride varnish was applied on the specimens and left for 1 hour (Duraphat, 2.26% F-); Group D (n=30): the same as Group B, followed by the same fluoride application as Group C; Group E (n=30): the specimens were covered with a glycerin gel as a control group; Group F (n=30): specimens were kept in Coca Cola 1 hour daily for 2 weeks. The mineral loss (vol% microm) and lesion depth (microm) were measured by microradiography. Data analysis was accomplished using the Kolmogorov-Smirnov, Kruskal-Wallis and Mann-Whitney U tests (p<0.05) (SPSS 11.0). The median mineral loss was statistically significantly higher in the non-fluoride groups (A: 271.20 vs C: 128.00 and B: 364.90 vs D: 151.10). The highest mineral loss was found in Group F (581.85 vol% microm) and was lowest in Group E (32.80 vol% microm). No statistically significant difference between groups was found for lesion depth.