Development of novel fluoride-releasing composites

Abstract

Due to the development of secondary caries, resin-based composites (RBCs) have short life spans. Several modifications have been studied to overcome this problem, such as incorporating ion-releasing fillers. In this study a previously lab-made fluoridated bioactive glass (F-BAG) was scaled-up industrially to establish whether scaling-up affected the fluoride release and flexural properties of RBCs containing this glass. Next, the effect of different monomers and F-BAG concentrations was assessed on selected physical and mechanical properties of RBCs. Materials and methods: One batch of the lab-made F-BAG and three nominally identical but separately made batches, made by a contract manufacturer (GTS, Glass Technology Services, UK), were initially assessed. First, RBCs made from 50:50 UDMA:TEGDMA and a barium aluminium-silicate glass as primary filler with 20wt% of the different F-BAG batches added. Additionally, an RBC was made with only the primary filler added and one in which the three GTS batches were mixed was made. Next the effect of different monomers (UDMA, HEMA, TEGDMA) was established on RBCs containing the same concentration of FBAG. Finally, the effect of F-BAG concentration was established when the monomer concentrations were fixed. All RBCs were assessed in terms of degree of conversion (DOC), water sorption, fluoride release, flexural strength (FS) and flexural modulus (FM). Results: For DOC and fluoride release RBCs containing the GTS F-BAGs were not significantly different to the lab-made glass containing RBCs and exhibited significantly lower water sorption and higher flexural properties after 1 month storage in distilled water. While the addition of HEMA significantly increased the fluoride release of the RBCs it detrimentally affected the flexural properties over storage time. Finally, there was an increase in fluoride release as the F-BAG concentration increased but when 30wt% or 40wt% F-BAG was added the flexural properties were reduced. Conclusion: The experimental F-BAGs composites made in this study represents promising results. Incorporating F-BAGs fillers in 10-40wt% showed good initial flexural properties which decreased over storage time especially for 30wt% and above.