Role of bioactive glass fillers in resin dentine adhesion

Abstract

Minimal invasive dentistry is considered as a standard approach based on prevention, control, and treatment of dental diseases. In adhesive resin dentistry, resin dentine interface is the weak link. To overcome these problems, various types of resin monomers e.g. bis-GMA, TEGDMA, HEMA and UDMA have been used for resin restorative materials. However, toxicity, polymerization shrinkage and hydrolytic degradation associated with bis-GMA and HEMA are still clinical concerns. Recently, efforts have been made to develop new resin monomers e.g. fluorinated UDMA (FUDMA) which is a fluorinated monomer. It was shown to have a surprisingly high double bond conversion, low volumetric shrinkage, less water sorption, and free of bis-phenol A. Although the mechanical properties of this novel resin monomer were investigated, its biological properties were unknown. The research questions of this study are: The first research question was aimed to investigate the micro-tensile bond strength of resin dentine adhesion of experimental FUDMA-TEGDMA adhesive resin with different weight percentages of bioactive glass (BAG) fillers. The resin dentine adhesion was evaluated by using the simulated pulpal pressure (SPP) technique and by water-wet bonding technique. The specimen were stored for 24h, 30 days, 6 months iii and 1 year in DI water. It was observed that experimental FUDMA-TEGDMA adhesive resin with 5 wt% of BAG fillers showed stable resin dentine adhesion The second research question investigated the cytotoxicity of experimental FUDMA-TEGDMA adhesive resin with BAG fillers to bis-GMA-HEMA based commercial adhesive resin and experimental adhesive resin with SiO2 filler and without fillers. MTT assay, ALP activity, total protein production and cell morphology using SEM were used to evaluate the cytotoxic potential of experimental FUDMA-TEGDMA adhesive resin. It was concluded that cell cytoplasmic projections were well developed in DI water group and experimental FUDMA-TEGDMA adhesive resin with BAG fillers. MTT assay showed significantly higher cell viability percentage in experimental FUDMA-TEGDMA adhesive resin with BAG fillers in comparison to other treatment groups. ALP activity and BCA Assay for protein production also showed significantly higher activity in FUDMA-TEGDMA based adhesive resin with BAG fillers. The third question investigated the antibacterial potential of experimental FUDMA-TEGDMA adhesive resin with bioactive glass fillers. MTT assay was carried out after 3 days of biofilm maturation while SEM and CLSM for 3 days and 7 days of biofilm maturation. SEM evaluation and confocal laser scanning microscopy analysis showed that experimental FUDMA-TEGDMA adhesive resin with BAG fillers possesses antibacterial potential in comparison to other experimental groups. The last research question was to evaluate the nanoleakage of experimental FUDMA-TEGDMA adhesive resin with BAG fillers after 24 h and 1 year of DI water storage. It was concluded that nanoleakage was significantly lower in experimental FUDMA- iv TEGDMA adhesive with BAG fillers than using bis-GMA-HEMA based adhesive resin and experimental FUDMA-TEGDMA adhesive without fillers. In conclusion, experimental FUDMA-TEGDMA adhesive resin with bioactive glass fillers has durable resin-dentine adhesion potential even after 12 months of water storage and do possesses less cytotoxic and more antibacterial potential than bis-GMA-HEMA bases adhesive resin.