The effect of different remineralizing agents and experimental bioactive glass on the microhardness, roughness, color and morphological changes of initial enamel caries

The aim of this study was to evaluate the data obtained from the application of different remineralization agents and experimental bioactive glass to in vitro induced initial enamel caries on extracted teeth. 87 permanent human molars, which were extracted for orthodontic or periodontal reasons and were free of caries, cracks, or hypoplastic defects, were used in this in vitro experiment. All samples underwent a 7-day pH cycling process. Each cycle consisted of 6 hours of demineralization and 18 hours of remineralization per day. Of the 87 molars, 30 were separated for Micro-CT analysis and 50 for microhardness, roughness, and color measurement. FE-SEM/EDS analysis was also performed on 7 of these remaining teeth. They were divided into five groups with 10 specimens in each group: Group C: Self-assembling peptide P11-4 (CurodontTM, Credentis AG, Switzerland), Group T: CPP-ACP (Tooth Mousse GC, Tokyo, Japan), Group B: Experimental 58S5 Bioactive Glass, Group F: 5% NaF varnish (Enamelast,Ultradent Products, Cologne, Germany), Group K: Non-treated (Distilled water,DW). Each group was divided into three subgroups: control, demineralization, and remineralization. Color, surface microhardness (Vickers), and surface roughness (Ra) were measured on the tooth surfaces at baseline, after demineralization, and after treatment. One sample from each group was examined for field emission scanning electron microscopy/energy dispersive spectroscopy (FE-SEM/EDS) analysis and elemental mapping analysis. In addition, Ca/P ratios of the enamel surfaces were evaluated. 30 specimens were reserved for Micro-CT analysis. Teeth allocated for Micro-CT underwent the same procedures: baseline, post-demineralization, and post-treatment. Statistical analysis was performed using repeated measures analysis of variance for surface microhardness, surface roughness, and Micro-CT results. The Bonferroni test was used for pairwise comparisons. The Tukey test was applied to analyze the samples in terms of color change (∆E). The significance level was accepted as p<0,05 in all statistical analyses. According to the microhardness values, the highest microhardness values were observed in Group B with 301,37±20,40 VHN and Group C with 296,23±12,02 VHN. Post-remineralization roughness values were similar in all groups and no significant difference was found (p>0,05). In terms of color measurements, Groups C and Group T differed significantly from Group K (p<0,05), There was no statistically significant difference between Group B, Group F and Group K (p>0,05). FE-SEM/EDS analysis revealed that Group T has the most irregular surface among the treatment groups. Additionally, according to the Ca/P ratio obtained from the EDS analysis, Group T exhibited lower values compared to the other groups, with a ratio of 1,40. Micro-CT results indicated no significant differences between groups except for Group K post-treatment (p>0,05). In conclusion, upon evaluating all procedures in terms of remineralization, the Group B and Group C were found to be more effective compared to the other groups. Keywords: Remineralization, microhardness, roughness, biomimetic, bioactive glass.