A low-shrinkage-stress and anti-bacterial adherent dental resin composite: physicochemical properties and biocompatibility.

Polymerisation shrinkage and biofilm accumulation are the two main problems associated with dental resin composites (DRCs) that induce secondary caries, which can cause restoration failure. Polymerisation shrinkage can lead to microleakage gaps between the tooth and the DRCs, causing the aggregation of bacteria and development of secondary caries. Reducing the shrinkage stress (SS) and improving the resistance to bacterial adhesion have always been the focus of this field in modifying DRCs. A thiol-ene resin system can effectively reduce the polymerisation SS via its step-growth mechanism for delaying the gel point. Fluorinated compounds can reduce the surface free energies, thereby reducing bacterial adhesion. Thus, in this study, a range of mass fractions (0, 10, 20, 30, and 40 wt%) of a fluorinated thiol-ene resin system were added to a fluorinated dimethacrylate resin system/tricyclo decanedimethanol diacrylate to create a fluorinated methacrylate-thiol-ene ternary resin matrix. DRCs were prepared using the obtained ternary resin matrix, and their physical and chemical properties, effect on bacterial adhesion, and biocompatibility were investigated. The results demonstrated that the volumetric shrinkage and SS of the DRCs were reduced with no reduction in conversion degree even after the thiol-ene resin system was added. All DRC-based fluorinated resin systems exhibited an excellent anti-bacterial adhesion effect, as evidenced by the colony-forming unit counts, live/dead bacterial staining, and crystal violet staining tests against Streptococcus mutans (S. mutans). The genetic expressions associated with the bacterial adhesion of S. mutans were substantially affected after being cultured with fluorinated DRCs. All fluorinated DRCs demonstrated good biocompatibility through the in vitro cytotoxicity test and live/dead staining images of the L-929 cells. The above results illustrate that the DRCs based on the fluorinated methacrylate-thiol-ene resin matrix can be potentially applied in clinical practice due to their low SS and anti-bacterial adhesion effect.

Preparation of Bis-GMA free dental resin composites with anti-adhesion effect against Streptococcus mutans using synthesized fluorine-containing methacrylate (DFMA).

With purpose of preparing Bis-GMA free dental resin composites (DRCs) with anti-adhesion effect against Streptococcus mutans (S. mutans), a new fluorinated dimethacrylate (DFMA) was synthesized and used as base resin of DRCs. Two reactive diluents TEGDMA and SR833s were mixed with DFMA separately to prepare resin matrixes. After mixing with inorganic fillers, two DFMA based DRCs were obtained and named as DT (DFMA/TEGDMA) and DS (DFMA/SR833s) according to the resin matrix composition. Bis-GMA based DRC (BT) was used as control. The double bond conversion (DC), bacteria adhesion, mucin adsorption, contact angle, surface free energy, volumetric shrinkage (VS), shrinkage stress (SS), water sorption (WS) and solubility (SL), flexural strength (FS) and modulus (FM) before and after water immersion were investigated, and all the results were statistically analyzed with ANOVA analysis. The results showed that DT and DS had comparable (ρ > 0.05) surface free energy which was lower than that of BT (ρ < 0.05). Compared with BT, with the same surface roughness (ρ > 0.05), less amount of S. mutans was accumulated on the surface of DT and DS (ρ < 0.05). In all DRCs, the DS had the best resistance to mucin adsorption (ρ < 0.05) due to its high hydrophobicity. Compared with BT, both DFMA based DRCs had advantages such as lower VS and SS (ρ < 0.05), lower WS and SL (ρ < 0.05), and better water resistance. The DS, which had antibacterial adhesion effect, mucin adsorption resistance, lowest VS and SL (ρ < 0.05), and the highest FS and FM no matter before or after water immersion (ρ < 0.05) was considered to have the best comprehensive properties in all DRCs.