Acid Buffer Capacity and Compressive Strength of Bioactive Restorative Materials in the Cariogenic pH Solution

Abstract

New bioactive materials were developed with claims of potential remineralization in the oral environment, particularly in acidic conditions. Direct bioactive restorative materials should resist mechanical load from mastication in saliva pH changes. However, the lack of evidence still exists on its bioactive ability to prevent demineralization. The purpose of this study was to evaluate the effects of cariogenic pH solution on acid buffer capacity and compressive strength of bioactive restorative materials. Thirty disc-shaped specimens of 5 commercial bioactive restorative materials were selected (diameter 15mm; thickness 1mm) and were immersed in 10ml of cariogenic pH solution (pH 4.7) at 37 ± 1°C. They were then evaluated for its buffer capacity using a pH meter every 30, 60, 90, 120, and 150 minutes respectively. Twelve specimens (diameter 4mm; height 6mm) of each material were immersed in a group of cariogenic pH solutions with pH 7 and 4.5 for 7 days. The compressive strength was tested using Universal Testing Machine and statistically analyzed by One-way ANOVA and Kruskal Wallis. The results showed an increase in pH of the cariogenic solution of all materials and an increasing immersion time. The compressive strength of Activa Bioactive Restorative had the lowest value after immersion in cariogenic solution pH 4.5. It can be concluded that bioactive restorative materials have a buffering capacity that can increase cariogenic pH solution towards neutral conditions within 150 minutes of immersion. Alkasite composite resin and Zirconomer Improved immersed for 7 days in cariogenic pH solution to stay stable at pH 4.5 and 7.