Effects of photopolymerization and autopolymerization of three different dual-polymerizing self-adhesive resin...

While dual-polymerizing self-adhesive resin cements have been widely used because of their bonding capabilities and ease of use, there is a lack of comprehensive data on their biocompatibility, particularly concerning the cytotoxic effects of different polymerization methods on cell viability.

The purpose of this in vitro study was to investigate the potential cytotoxic effects of 3 different dual-polymerizing self-adhesive resin cements polymerized by light polymerization or autopolymerization on L929 cells in vitro using by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide (MTT) test.

Three different dual-polymerizing self-adhesive resin cements (Calibra Universal; Dentsply Sirona Inc, SpeedCEM Plus; Ivoclar AG, and TheraCem Ca; Bisco Inc) were light or autopolymerized in polytetrafluoroethylene (PTFE) molds containing Ø5-mm and 2-mm-thick cells in accordance to the manufacturer's instructions. The specimens were incubated in Dulbecco Modified Eagle Medium (DMEM-High; Capricorn Scientific GmbH) for 48 hours and the extracts were obtained. The 100% concentration of the extract was diluted and extracts at 66.7%, 44.4%, 29.6%, and 19.8% concentrations were obtained. Specimen extracts at 5 different concentrations were incubated with L929 (NCTC clone 929: CCL 1; American Type Culture Collection) mouse fibroblast cells in 96-well tissue culture plates at 37 °C and 5% CO₂ for 24, 48, and 72 hours. At the end of the incubation period, the effects of the materials on cell viability were evaluated with the MTT test. The data were analyzed using a statistical software program (IBM SPSS Statistics, v25.0; IBM Corp) (α=.05), employing ANOVA and the Tukey's HSD test.

All tested cement specimens significantly reduced cell viability (P<.05). Cell viability decreased with increasing concentration and incubation time in all specimens tested. The light-polymerized SpeedCem Plus showed the least cytotoxicity regardless of concentration and incubation time, followed by TheraCem Ca. However, the autopolymerized Calibra Universal significantly reduced cell viability. Cell viability rate of all light polymerized cements was considerably higher than autopolymerized cements (P<.05).

All the tested self-adhesive resin cements caused a significant reduction in viability of L929 cells. The composition of the self-adhesive resin cement and the activation type of polymerization affected cytotoxicity.