Glass hybrid, but not calcium hydroxide, remineralized artificial residual caries lesions in vitro.

Abstract

For deep carious lesions, less invasive carious tissue removal is recommended. The resulting residual carious lesions might benefit from remineralization by lining or restoration materials. We aimed to compare mineral gains in artificial residual lesions provided by calcium hydroxide and glass hybrid materials in combination with pulpal fluid simulation. On the coronal aspect of human dentin discs (n=20), artificial carious lesions were induced using acetic acid. Median mineral loss ΔZ [25th/75th percentiles] of resulting lesions was 1643 [1301/1858] vol%μm. One third of each disc served as baseline sample. The remaining disc was divided into four groups, each being covered with one experimental material (n=20/group): flowable composite (control (CO)), setting or non-setting calcium hydroxide liner plus flowable composite (CH-S, CH-NS), and glass hybrid (GH). Samples were mounted in a dual-chamber device. Pulpal surfaces were exposed to simulated pulpal fluid at 2.94kPa. Coronal surfaces were exposed to artificial saliva and rinsed with 200ppm NaF every 2weeks. After 12weeks, mineral loss differences (ΔΔZ) were assessed using transverse microradiography. Electron probe microscopic analysis was used to measure fluoride and strontium concentrations. Mineral gains were not significantly different between CO (ΔΔZ=372 [115/501] vol%μm), CH-S (ΔΔZ=317 [229/919] vol%μm), or CH-NS (ΔΔZ=292 [130/579] vol%μm; p>0.05/Wilcoxon test) but significantly increased in GH (ΔΔZ=1044 [751/1264] vol%μm, p<0.001). Samples in GH showed fluoride and strontium enrichment deep into the dentin. Such enrichment was not found in CO. Within the limitations of this study, GH, but not calcium hydroxide, provided coronal remineralization of residual carious lesions. Glass hybrids might provide additional remineralization of residual carious lesions. The functional implications of this mineral gain need to be evaluated.