EVALUATION OF MECHANICAL PROPERTIES OF FLUORIDE-RELEASING DENTAL MATERIALS AFTER MULTIPLE FLUORIDE RECHARGE/DISCHARGE APPLICATION

This study aimed to determine the mechanical properties of fluoride-releasing dental materials after an accelerated fluoride recharge/discharge procedure. Two fluoride-releasing glass ionomer types of cement (Ketac Molar Easymix and IonoStar Molar), a resin-modified glass ionomer (Photac Fil Quick Aplicap), and two compomers (Compoglass F and Glasiosite) were used in this study. A total of 30 rectangular specimens and 30 disk specimens of each material were prepared and placed in distilled/deionized water (n = 5). The amount of fluoride released was analyzed from the materials for 7-day discharge, 1st recharge, 7-day discharge, 2nd recharge, and 7-day discharge, and 3rd recharge. The de/pre- and post-recharge fluoride release were measured using an ion chromatography for 24 days. The flexural strength and microhardness of each group were evaluated. The microhardness of all restorative materials showed no significant change (p > 0.05) over the experimental period. The flexural strength properties of the restorative materials did not change within the time of the study. The study showed that the fluoride release/uptake causes no effect on the mechanical and physical properties of dental materials

The Effect of Two Different Light-Curing Units and Curing Times on Bulk-Fill Restorative Materials

This study aimed to evaluate the effect of two different light-curing units and curing times on the surface microhardness (SMH), compressive strength (CS), and volumetric shrinkage (VS) of four restorative materials (FiltekTM Z250, FiltekTM Bulk Fill Posterior, Beautifil® Bulk Restorative, ACTIVATM BioACTIVE). For all tests, each material was divided into two groups depending on the curing unit (Woodpecker LED-E and CarboLED), and each curing unit group was further divided into two subgroups according to curing time (10 s and 20 s). SMH was evaluated using a Vickers hardness tester, CS was tested using a universal testing machine, and VS was measured using video imaging. In all the restorative materials cured with Woodpecker LED-E, the 20 s subgroup demonstrated significantly higher SMH values than the 10 s subgroup. In both light-curing time subgroups, the CarboLED group showed significantly higher CS values than the Woodpecker LED-E group for all restorative materials except FiltekTM Bulk Fill Posterior cured for 20 s. ACTIVATM BioACTIVE showed significantly greater volumetric change than the other restorative materials. A higher curing light intensity and longer curing time had a positive effect on the SMH and CS of the restorative materials tested in this study. On the other hand, curing unit and time did not show a significant effect on the VS values of restorative materials