The role of camphorquinone in the cytotoxicity of universal dental adhesives

This work aimed to examine the effect of unreacted substances of four universal adhesives on cell viability, taking into account different sample preparation protocols. The protocols for sample preparation were as follows: P1: Disc-shaped specimens made of the adhesive material itself; P2: filter paper disc impregnated with the adhesive system; P3: bovine dentin disc impregnated with the adhesive system. The UHPLC/Q-TOF-MS spectroscopy was utilized to detect the type and quantity of unreacted substances released. The cell viability of the universal adhesives was evaluated considering the sample preparation protocol, as well as the different concentrations of each compound detected by the UHPLC/Q-TOF-MS spectroscopy in their isolated form. The WST-1 assay was employed to assess cell viability. From the extraction media, HEMA, BisGMA, CQ, EDAB, TPO, and UDMA were identified. When evaluated in P1, significantly higher amounts of CQ were detected in all of the universal adhesives (p<0.001). The sample preparation protocol was found to significantly influence cell viability (p<0.001). Notably, all universal adhesives exhibited a cytotoxic effect only when using the P1 protocol. Among the analyzed substances, CQ was identified as the most cytotoxic component (p<0.05). It was observed that disc-shaped specimens made with the material itself resulted in an overestimation of the cell viability outcomes for the universal adhesives.