Evalution of the effect of bioctive glass containing gel on remineralization in primary TEETH with artificial caries

The aim of this in vitro study is to evaluate the remineralization efficiencies of micro- and nano-sized bioactive glass (BAG)-containing gel formed by a newly developed technique, compared to fluoride varnish agent in artificially created initial enamel caries. In the study, 60 caries-free primary teeth were used. 60 primary teeth were divided into two in the mesiodistal or buccolingual direction using a thin diamond blade that cuts on both sides in a water-cooled cutting device. Enamel sections of approximately 5 mm width, 5 mm length and 2 mm thickness were obtained from the buccal, lingual, mesial or distal parts of the teeth, which have flatter surfaces. Enamel sections of 60 primary teeth were embedded in epoxy resin with the enamel surfaces exposed. 30 samples were reserved for computerized microtomography analysis (Micro-CT), while the remaining 30 samples were reserved for Scanning Electron Microscopy- Energy Dispersive Spectroscopy (SEM-EDS) analysis. The pH cycle, in which the oral environment is simulated in vitro, was applied to the enamel sections in which initial caries was created with the demineralization solution. A 6-day pH cycle phase was applied to 3 experimental groups, which were formed according to the use of fluoride varnish, micro-sized bioactive glass-containing gel and nano-sized bioactive glass-containing gel remineralization agents. The samples were determined by Micro-CT analysis for mineral density change (BMD) after demineralization and after pH cycling; The morphological changes on the surface and ion differences were evaluated with SEM-EDS analysis after pH cycling application. Statistical analysis of the data was performed using the SPSS 23.0 program (IBM, Chicago, USA). Two-way analysis of variance was used to compare BMD values within and between groups. Tukey test was used in multiple comparisons. In the comparison of Ca, P, Ca/P and Si values by weight (%) according to the groups, data that did not show normal distribution were compared with Kruskal Wallis, and normally distributed data were compared with one-way analysis of variance (ANOVA). Tamhane's T2 test was used as the distributions were not homogeneous in multiple comparisons. Analysis results are presented as mean ±s.dev, median (minimum-maximum). Evaluation of the results was made at p< 0.05 significance level. The effect of remineralization agents applied to the initial caries lesions on the enamel surface on BMD values was found to be statistically significant (p= 0.001). There was a statistically significant difference between the mean BMD value obtained after remineralization in the fluoride varnish group and the mean BMD value obtained after remineralization in the micro-BAG group (p<0.001). There is a statistically significant difference between the mean BMD value obtained after remineralization in the fluoride varnish group and the mean BMD value obtained after remineralization in the nano BAG group (p<0.001). There was no statistically significant difference between the mean BMD value obtained after remineralization in the micro-BAG group and the mean BMD value obtained after remineralization in the nano-BAG group (p>0.05). While Ca+2 values by weight (%) measured on the enamel surface did not differ between groups (p=0.140), P+1 values by weight (%) differed between groups (p< 0.001). The weight (%) Ca/P values measured on the enamel surface also did not differ between the groups (p=0.503). In addition, there was no statistically significant difference between the groups containing bioactive glass in terms of weight (%) Si+4 values measured on the enamel surface (p=0.199). In our study, the remineralization effect of micro and nano-sized BAG- containing gel agents on initial enamel caries lesions was found to be lower than the fluoride varnish agent. Keywords: Bioactive glass, initial enamel caries, primary tooth, remineralization