Monomer Elution of Additive- and Subtractive-Manufacturing Resins for Permanent Restorations.

PURPOSE: To evaluate the elution of residual monomers from resins used in additively and subtractively manufactured permanent restorations over a period of 1 month, using high performance liquid chromatography (HPLC). MATERIALS AND METHODS: Two additive manufacturing permanent crown resins (Crowntec [CT] and VarseoSmile Crown Plus [VS]) and a subtractive-manufacturing resin nanoceramic (Cerasmart [CS]) were used to fabricate 30 disc-shaped samples (10 x 2 mm; n = 10). The elution of bisphenol A ethoxylate dimethacrylate (BisEMA), urethane dimethacrylate (UDMA), and triethylene glycol dimethacrylate (TEGDMA) monomers was measured with HPLC at 1 day and 30 days after immersion. One-way ANOVA and post-hoc Tukey tests were used to evaluate differences in eluted monomer concentrations. Paired-sample t tests were used to test the differences in monomer concentration between storage times. RESULTS: CS released BisEMA and UDMA residual monomers, while VS and CT released BisEMA and TEGDMA residual monomers. The residual monomer elution from CT was consistently lower than that from VS for both BisEMA (P < .001) and TEGDMA (P < .001). CS showed a decreasing release pattern in BisEMA (P = .002) and UDMA (P < .001) residual monomers, whereas VS and CT showed an increasing release pattern in BisEMA (P < .001) and TEGDMA (P < .001) residual monomers. CONCLUSIONS: The additive-manufacturing composite resins released higher amounts of residual monomers than the subtractive-manufacturing resin nanoceramic. Although the amounts of residual monomers released in the additive manufacturing composite resins increased over time in contrast to the subtractive manufacturing resin nanoceramic, these values were below cytotoxic levels.