Effects of two different materials with hi̇gh flouride concentration on the bond strength of composite to dentin

The aim of this in vitro study was to investigate the effects of two different materials with high fluoride concentration used in the treatment of dentin caries and dentin hypersensitivity on the bond strength of the composite to sound and demineralized dentin immediately after fluoride treatments and fluoride aging. Sixty caries-free human molars were included in this study. Ten of the teeth were randomly allocated for scanning electron microscopy imaging. Fifty teeth were divided into bucco-lingual/palatal halves, placed in acrylic blocks, and 100 dentin samples were created by removing the buccal/lingual/palatinal enamel. Half of the dentin specimens were demineralized by soaking into demineralization solution. The samples were then randomly divided into 10 groups, with the number of specimen in each group (n=10). Topical fluoridated agents silver diamine fluoride/potassium iodide (SDF/KI); Riva Star, SDI, Australia) and fluoride varnish (FV; Fluor Protector, Ivoclar Vivadent, Liechtenstein) were applied to the dentin surfaces in the experimental groups, and composite resin (Gradia Direct Posterior, GC, Japan) was bonded to all samples with a universal adhesive (Solare Universal Bond, GC, Japan) immediately after the application of the fluoridated products and the aging process of fluoridated surfaces by thermal cycle. Shear bond strength test (SBST) was used to measure the bond strength. After SBST, the samples were examined under a stereomicroscope and the failure types were evaluated. Whether the mean of shear bond strength test values differed between all groups was evaluated with One-Way ANOVA. With the aim of general data comparison, a three-way ANOVA analysis was performed with dependent variables as follows: time (immediate and after aging of fluoride), fluoride treatments (SDF/KI, FV) and dentine condition (demineralized and sound). In case of difference between the groups, Post Hoc comparison tests were used. Statistical significance level was taken as p= 0.05. The use of fluoride products did not make a significant difference in bond strength compared to the control groups (p>0.05). There was no statistically significant difference between the two products in terms of the effect on bond strength (p>0.05). The aging of fluoride materials significantly decreased the bond strength compared to the immediate bonding groups (p<0.05). Statistically, sound dentin groups showed significantly higher bond strength values than demineralized dentin groups (p<0.05). The use of GDF/KI and FV did not adversely affect the bond strength of composite restorations to sound and demineralized dentin.