Dental adhesives procedures allow the recovery of dental esthetics and function after tissue loss by dental caries or fracture, color changes, and teeth shape or position correction. This study aimed to assess in vitro cytotoxicity for one of each commercially available adhesive strategies - Adper™ Scotchbond™ 1 XT (SB1, etch-and-rinse), Clearfil™ SE Bond 2 (CSE, self-etch) and Scotchbond™ Universal (SBU, universal).

Odontoblast-like cells (MDPC-23) were cultured and exposed to adhesives extracts. To access cell metabolic activity, viability, types of cell death and cell cycle, MTT, SRB, double labelling with annexin V and propidium iodide and labelling with propidium iodide/RNAse were performed. Cultures were stained with May-Grunwald for qualitative morphological grading of cytotoxicity.

The SB1, CSE and SBU extracts determined a significant reduction in cell metabolism and viability. This reduction was higher for prolonged exposures even for less concentrated extracts. CSE extracts significantly reduced cell’s metabolic activity at its higher concentrations, since 2 hours of exposure. At the lowest concentrations, after 24 and 96 hours, SB1 extracts reduced more or as equal the metabolic activity as CSE extracts. Regarding cell’s viability, SBU extracts were the least cytotoxic, and CSE were significantly more cytotoxic than SB1 and SBU. The adhesives determined a reduction in the number of viable cells and an increase in the number of apoptotic, late apoptosis/necrosis and necrotic cells. Moreover, a decrease in the number of cells in S and G2/M phases and an increase in the number of cells in Pre-G0 and G0/G1 phases was observed. These changes were dependent on the adhesive, its concentration and the time of incubation. CSE extracts were the most cytotoxic and were classified as having a higher degree of reactivity, leading to greater inhibition of cell growth, with destruction of the cell’s layers.