In vitro analysis of dentin remineralization using glass ionomer cement with or without calcium orthophosphate particles or with mineral trioxide aggregate

Abstract

Minimally invasive restorative approaches have stimulated the search for materials capable of acting in the dentin remineralization process, not only in relation to mineral gain, but also to the functional recovery of the affected tissue. The present project aims to analyze in vitro the effect of a Conventional glass Ionomer Cement (CIV) containing or not calcium orthophosphate particles and the mineral trioxide aggregate (MTA) in the dentin remineralization process. The null hypothesis is that the use of these materials does not promote an increase (1) of the mineral content or (2) in mechanical properties (modulus of elasticity and nanohardness) of demineralized dentin. Calcium orthophosphate particles will be synthesized by precipitation and characterized by X-ray diffractometry, density, laser scattering and scanning electron microscopy. In the second stage, dentin blocks (2 x 2 x 1.5 mm) will be partially demineralized by immersion in calcium phosphate and acetic acid solution (pH 5.0) for 66 h and restored with a glass ionomer cement (Fuji IX), a glass ionomer cement with addition of 5% (by weight) calcium orthophosphate, a calcium silicate-based material (Biodentine) or a restorative composite (Filtek Z250 - control). Specimens will be kept in simulated body fluid at 37°C for 60 days. The mineral gain will be analyzed by ATR-FTIR spectroscopy and transmission electron microscopy (n=5) in periods I0 (before demineralization), I1 (immediately after demineralization) and after two, four and eight weeks. The nanohardness and dentin modulus of elasticity will be obtained by means of the nanoindentation test (n=10) after 60 days of storage in SBF. Additionally, the release of calcium and fluoride ions by the materials will be determined in specimens (5 x 1 mm, n=5) immersed in SBF for two, four and eight weeks. If the data meet the normality and homocedasticity requirements, it will be analyzed through ANOVA of two way with repeated measurements/Tukey test (ART-FTIR, ion release) or ANOVA of one way/Tukey test (nanohardness and modulus of elasticity) with a significance level of 5%. (AU)