In vitro investigation of the contribution of current fissure sealant materials to enamel remineralization

The present study aimed to contribute to preventive dentistry by evaluating demineralization resistance and remineralization abilities of current and experimental fissure sealant materials using actual and modern analysis methods. The remineralization capacity of fissure sealant materials to occlusal enamel was evaluated in a two-part study using two different in vitro methods: the microhardness method and SEM-EDX analysis. The experimental groups were; Group-A: Amorphous calcium phosphate (ACP) containing fissure sealant applied group (Aegis, Bosworth), G: Carbomer and fluorapatite-reinforced glass ionomer-based fissure sealant applied group (GCP Glass Seal, GCP), F: High fluoride-releasing glass ionomer-based fissure sealant applied group (Fuji VII / Triage, GC), C: Fluorid-supported, long-term fluor-releasing resin-based fissure sealant applied group (Conseal F, SDI), N: Fluor-releasing flowable composite resin (Natural Flow, DFL) applied group, Group S: Control group consisting of intact teeth not subjected to any treatment and Group D: Control group composed of teeth not subjected to fissure sealant but subjected to pH cycle. Six groups (S, A, F, G, C, and N, with n = 15 in each group) were evaluated using the microhardness method, and seven groups (S, A, F, G, C, N, and D, with n = 10 in each group) were evaluated using the SEM-EDX analysis. The pH cycle model was used to form artificial caries, with the samples exposed to different pH cycles for 24-h periods for 14 days. Buccolingual sections were then taken from each tooth, and cross-sectional microhardness measurements were obtained from three depths (20, 50, and 80 μm) of the fissure margins and buccal window sections in the six experimental groups (S, A, G, F, C, and N). To examine the mineral content of the fissure bases of the seven experimental groups (S, A, F, G, C, N, and D), total atomic and weight percentages (% at and % wt) of seven elements (Ca, P, F, O, C, Na, and Si) were calculated, and the % Ca/P ratios of the groups were then evaluated by SEM-EDX analysis. A one-way variance analysis was conducted to evaluate differences between the averages of the independent groups. Tukey's HSD test was used for multiple comparisons, and % 95 confidence intervals were applied in the statistical analysis tests. A value of p < 0.05 was considered statistically significant. According to the results of the microhardness and SEM-EDX analyses, ACP (Aegis), glass carbomer (GCP Glass Seal), and glass ionomer-containing fissure sealant (Fuji, Triage) materials applied in groups A, G and F inhibited demineralization on occlusal surfaces during the pH cycle and contributed to remineralization on the enamel. The contribution of these three materials to enamel microhardness was comparable at depths of 20, 50, and 80 μm from the fissure sealant margins. The findings of both the microhardness measurements and SEM-EDX analysis showed that the remineralization abilities and enamel demineralization inhibition of the materials applied in groups A, G, and F were statistically significantly higher than those of the fluor-releasing resin systems applied in groups C and N. The results of both analyses demonstrated that the demineralization resistance activity of the fluor-releasing resin-based fissure sealant (Conseal-F) applied in group C was better than the fluor-releasing flowable composite resin (Natural Flow) applied in group N. As a result, the remineralization capacity on enamel of amorphous calcium phosphate and ionomer based fissure sealants were found more effective than flour-releasing resin systems. There are few studies evaluating the efficacy of ACP-containing and glass carbomer-containing fissure sealant materials on tooth hard tissues. We consider that more researches are needed that the remineralization activities of those materials are evaluated by different analysis methods in both in-vitro and in-vivo conditions. Key words: Remineralization, fissure sealant, amorphous calcium phosphate, glass carbomer, micro-hardness, SEM-EDX