65 - Cytotoxicity assessment of a self-etching primer and an orthodontic composite resin in L929 cells

Abstract

Self-etching primers have simplified the process of direct bonding of dental resins by eliminating the rinsing step. The aim of the present study was to evaluate the cytotoxic effects of released residual substances from Transbond Plus Self-etching Primer (TSEP) (3M Unitek Ortho Prod, Monrovia, Calif) and Transbond XT (3M Unitek Ortho Prod, Monrovia, Calif). The study was approved by the Ethics Committee of UFRJ (CAAE: 13971513.0.0000.5257). Six human premolars and orthodontic stainless-steel brackets (Morelli, São Paulo, Brazil) were divided into two groups (n=3), as follows: Group I (Tooth + TSEP + Transbond + bracket + Light-curing) and Group II (Tooth + TSEP + Light-curing + Transbond + bracket + Light-curing). After samples immersion in the culture medium, supernatants aliquots were collected in triplicate and placed in contact with L929 cells for toxicity analysis after 0, 24, 48, 72 hours, 7, 14, 21 and 28 days. Cell viability was determined by "dye uptake" and was read in spectrophotometer. There were statistic significant differences between the number of the living cells present in the groups tested compared with the cell control group (P<0,05). Group I demonstrated toxicity until 7 days and Group II until 14 days (P<0,05). After 21 and 28 days, no significant toxicity was observed in either groups, suggesting that the release of toxic monomers occurs primarily in the first two weeks. The TSEP, Transbond XT composite associated to stainless steel brackets reduced cell viability in the first days, with toxicity persisting up to 14 days in the group with a two-step light curing.