Comparative evaluation of remineralization, fluoride release and physical properties of conventional GIC following incorporation of 1% and 2% zinc acetate: An in vitro study

Abstract

Context: Modern concepts of operative dentistry, popularly known as Minimal intervention dentistry, propose that only the infected dentin should be removed, leaving the affected dentine that has the potential to remineralize. Mineralization of the tooth structure left in the cavity is likely to occur due to the application of fluoride- releasing material such as glass ionomer cement (GIC). Aim: The aim of this study was to evaluate whether the remineralizing potential of GIC can be enhanced with the addition of zinc acetate. Study Design: An experimental in vitro intergroup randomized control trial. Materials and Methods: This study consisted of three groups. Group I was conventional GIC, Group II was GIC with 1% zinc acetate and Group III was GIC with 2% zinc acetate. Thirty human premolars (10 in each group) extracted for therapeutic reasons were used in the first part of this study. Standardized class V cavities were prepared on the buccal and lingual surfaces. Teeth were sectioned longitudinally to get one buccal and one lingual half, in which one half was used as the control and the other half was used as the test specimen. Artificial caries- like lesions were produced and subsequently restorations of experimental specimens were performed. The depth of demineralization and remineralization were photographed under a polarized light microscope and quantified using a computerized imaging system. In the second part of the study, fluoride ions released were measured after 24 h and 7 days using an ion sensitive electrode. In the third part of the study, the setting time was calculated using Vicker's apparatus, as the time elapsed from the beginning of mixing till the time when the needle could no more make a circular indentation on the cement. In the fourth part, specimens prepared using Teflon moulds of standardized dimensions were subjected to shear bond strength analysis using a universal testing machine. Statistical Analysis: The obtained results were subjected to statistical analysis using Student's paired and unpaired 't' test, One way ANOVA, Post hoc Tukey's test. Results: In part one of the study, Group III showed the highest amount of remineralization, followed by Group II. All the groups showed statistically highly significant (P < 0.001) zones of remineralization; the difference between the groups was statistically highly significant (P < 0.001) as well. Part two of the study showed that fluoride release was highest in Group III, the difference being statistically highly significant from Group II and Group I at both the time intervals (P < 0.001). However, the amount of fluoride ions released on the 7 th day were lesser than that at 24 h in all the groups (P < 0.001). Parts three and four of the study showed that there was no statistically significant difference between the groups with respect to setting time and shear bond strength (P = 0.82 and 0.64, respectively). Conclusions: Incorporation of zinc acetate to glass ionomer at 2% w/w was effective in enhancing the remineralization property and fluoride release of the cement without affecting its setting time and shear bond strength.