In vitro elemental and micromorphological analysis of the resin-dentin interface of bioactive and bulk-fill composites

Purpose: To evaluate the bonding interface and the remineralization potential of a bioactive restorative material on demineralized dentin compared to a conventional bulk-fill resin composite restoration. Methods: Twelve caries-free human molars were used in this study. Specimens were randomly divided into two groups according to the type of restorative material used (n=12); an injectable resin-modified glass-ionomer restorative [Activa BioActive-Restorative (ABR)] and a bulk-fill composite [3M Filtek One Bulk Fill Restorative, (BFC)]. Each restored specimen was sectioned in two semi-equal halves along the long axis of the teeth perpendicular to the resin dentin interface with a water-cooled diamond disk at low speed. The restoration-dentin interfaces were scanned under SEM to observe micromorphological analysis; then an elemental analysis of the interface was performed using an energy dispersive X-ray (EDX) spectroscopy. Results: Quantitative data were described using median (minimum and maximum) after testing normality using the Shapiro-Wilk test. Mann-Whitney U test was used to compare the BFC and ABR. Higher mean values of Ca were identified and related to the ABR material, which provided more Ca ions than BFC. The comparison of Ca and P between materials showed a significant difference in the amount of Ca provided by ABR versus BFC. ABR restorations presented a thicker, and superior remineralization interface compared to the bulk-fill resin composite