Remineralization Efficiency of Bioactive Fiber-Composite After 30 Months of Storage
Objectives: To evaluate the long-term mineralizing effect of an experimental ion-releasing fiber-reinforced flowable composite (Bio-SFRC) used as a cavity liner. Methods: A total of 16 MIH-extracted molars were restored with and without the Bio-SFRC as a liner under composite filling and stored in simulated body fluid (SBF) at 37°C for 30 months. Each tooth received two occlusal restorations. Half of the restorations (n=8) were made of a commercial conventional particulate-filled composite (PFC; G-aenial Universal Injectable) alone or with the Bio-SFRC liner. The other half (n=8) were restored using either resin-modified glass ionomer (RMGIC; Fuji II LC) alone or the PFC composite with the Bio-SFRC liner. All cavities were phosphoric acid-etched for 20 seconds before applying restorations. Dentin remineralization potential was assessed at three regions (coronal, middle, and apical) under the restorations using SEM/EDS (microstructure & Ca/P ratio), micro-CT (density), and micro-indentation (hardness) analysis. Results: Micro-CT analyses revealed that the mineral density of dentin adjacent to the Bio-SFRC liner was higher (1.53 g/cm3) than that of the commercial PFC composite (1.44 g/cm3). However, RMGIC exhibited the highest dentin density at the interface (1.64 g/cm3), with a statistically significant difference (ANOVA: p<0.05). Additionally, dentin hardness at the interface with RMGIC was higher (0.88 GPa) than with Bio-SFRC (0.78 GPa), although the difference was not statistically significant (ANOVA: p>0.05). The Ca/P ratios of dentin varied among the teeth with different restorations, ranging from 1.49 to 1.60, with the highest ratio observed at the interface with Bio-SFRC. Strontium was detected in the dentin around the RMGIC restorations. Conclusions: Bio-SFRC positively influences dentin remineralization, showing higher mineral density and Ca/P ratios at the interface. These findings suggest that Bio-SFRC is a promising restorative material for managing MIH teeth.