Chemical exchange between dentin pre-tratment with CPP-ACP and GIC on demineralized dentin in deciduous molars

Abstract

Aim: To assess the effect of the chemical exchange between restorations using high-viscosity glass ionomer cement (GIC) and the casein phosphopeptide amorphous calcium phosphate CPP-ACP treatment on primary demineralized dentin by analyzing the hardness changes caused by calcium, phosphate and fluoride uptake. Methods: 40 deciduous molars were selected and randomly assigned to four groups according to dentin pretreatment and dentin condition. Class I cavity preparations were performed in 40 sound primary molar samples, equally divided into groups G1 (sound dentin) and G2 (demineralized dentin). Sub-groups (n=10) were set in order to aid in investigating the isolated GIC action or its association with CPP-ACP. This study was conducted in vitro and assessed the chemical exchange under two conditions, namely: sound and demineralized dentin (pH cycling); This in vitro study examined the mechanical and chemical exchange under two conditions – sound and demineralized dentin (pH cycling) – to simulate the mineral loss that occurs for the caries lesion. The 40 teeth first received a topical application of ACP-CPP and a restoration of high viscosity GIC. The 20 teeth assigned to the groups (G1 and G2) were only restored with GIC. The specimens were sliced and prepared for Knoop hardness test (KHN), Micro Raman, and FEG microhardness analysis groups. The statistical analysis used ANOVA and Bonferroni post-test at a 5% significance level. EDS (Dispersive Energy Spectroscopy) and FEG (High-resolution scanning electron microscope) data were qualitatively described. Results: Increased hardness was observed in all sites that had direct contact with GIC in the sound and demineralized dentin samples in all groups (p<0.001); microhardness showed no differences after CPP-ACP application (p>0.05). The direct contact between GIC in sound and demineralized dentins resulted in an increased phosphate peak in the FEG and EDS evaluations. Conclusion: ACP-CPP associated with GIC showed no increase in microhardness values of the demineralized dentin substrate. The exchange between the GIC and the demineralized dentin may induce changes in the mechanical properties of the substrate and in the uptake of mineral ions.Uniterms: dentin; prevention; caries; remineralization; demineralization; biomechanics