Antioxidants as a novel dental resin-composite component: Effect on elution and degree of conversion

Objective

Ascorbic acid (Asc) and N-acetylcysteine (NAC) were reported to reduce genotoxicity induced by dental (co)monomers and their epoxy metabolites. The aim of the present study was to investigate Asc or NAC as novel components in light-curable methacrylate based dental composites regarding their effects on degree of conversion (DC) and elution of composite components. Additionally, the release of Asc or NAC was determined.

Methods

Asc or NAC (1, 0.1, 0.01 or 0?wt%) was experimentally incorporated into the composites Venus^®, Grandio^® and Filtek^TM Supreme XTE and polymerized according to the instruction of manufacturers. The samples were elussted in methanol and water. For each composite-antioxidant mixture and elution medium four samples (n?=?4) were prepared. The eluates were analyzed by gas chromatography/mass spectrometry (GC/MS), high-performance liquid chromatography/ultraviolett/diode array detection (HPLC/UV/DAD) and high-performance liquid chromatography/fluorescence detection (HPLC/FLD). DC of composite-antioxidant mixtures was measured in real-time with Fourier transform infrared spectroscopy (FTIR).

Results

The highest concentrations of eluted Asc were 313.98?μM (Venus^®-1?wt% Asc; 1 day; methanol) and 245.34?μM (Filtek^TM Supreme XTE-1?wt% Asc; 5?min; water). The highest concentrations of eluted NAC were 42.99?μM (1 day; Filtek^? Supreme XTE-1?wt% NAC; 1 day; methanol) and 108.11?μM (Filtek^? Supreme XTE-1?wt% NAC; 7 day; water). Triethylene glycol dimethacrylate (TEGDMA) elution was significantly increased in Venus^®-1?wt% Asc and Grandio^®-1?wt% Asc (1 day and 7 day methanol/water), compared to control. No significant difference was found for TEGDMA elution in Filtek^? Supreme XTE-1?wt% Asc/NAC. DC was significantly decreased compared to control (=?composite without antioxidant) in Grandio^® and Filtek^? Supreme XTE after 1, 0.1 and 0.01?wt% Asc incorporation and in Venus^® after 1 and 0.1?wt% Asc incorporation. For composite-NAC mixtures, only DC of Grandio^®-1?wt% NAC was significantly reduced.

Significance

Incorporation of NAC (1?wt%), as a novel composite component, into Filtek^? Supreme XTE, had no effect on DC and composite component elution, and supplies sufficient amount of antioxidant which may reduce toxicity. Therefore, it represents a beneficial mixture.