Remineralization of Carious Dentin with Bio-active Restorative Materials

Abstract

Caries detector differentiation of partially demineralized affected dentin: the action of organic acids of certain cariogenic bacteria-in vivo physiological remineralization occurs with time. Some reports suggest that certain bio-active adhesives may stimulate remineralization as well as provide long-term bonding durability. In this study, artificial lesions were restored with a bio-active ion-releasing agent and physiological remineralization of the resin-dentin interface below the in vitro carious lesions were measured for nano-hardness, compositional changes and SEM at 1 and 12 weeks. Class I cavities were placed throughout the teeth of six extracted human third molars. Each cavity was subjected to lactic acid and cariogenic bacteria (Streptococcus mutans). The in vitro caries was removed with a low speed round bur and the cavity was restored with one of two materials. Bio-active restorative materials Fluoro Bond Shake One and Beautifil Flow F02 including S-PRG (Surface reaction type Pre-Reacted Glass-ionomer) filler (SO) while Clearfil Mega Bond and Clearfil Majesty LV served as the MB-control. All materials were placed according to manufacturer's directions. After restoration, a hydrostatic Ringer's solution at a fluid pressure of 15cm H₂O was maintained to the pulp chamber of each tooth and stored at 37℃ in 100% relative humidity for either 1 week (1w) or 12 weeks (12w). After storage, each specimen was cut perpendicular to the resin-dentin interface and each half surface was polished. The nano-hardness site of each resin-dentin interface was measured using a 1mN load at each site at 5μm pitch from the cavity floor to 100μm and 100μm pitch from 100μm to 500μm. Each site was determined at 10 points in a horizontal direction with 3 measurements for each specimen. Nano-hardness compared t-test and one-way ANOVA, Tukey's test (α=0.05). The other cut half was assayed for its compositional elements using energy dispersive X-ray (EDX) and FE-SEM ultrastructural analysis. Nano-hardness of the resin-dentin interface compared SO to MB-control at 12w, from the interface to the 100μm, SO showed an increased hardness values against the MB-control. Additionally, we compared the SO resin-dentin interface at 1w and 12w, from the interface to the 100μm, 12w showed higher hardness values than 1w. EDX data indicates the rate of Ca and P of the MB-control was less than SO at 1w and 12w. Sr was found subjacent to the SO restorations, suggesting dentin remineralization of the in vitro lesion under the bio-active with S-PRG filler.