Effect of heat treatment on cytotoxicity of self-adhesive resin cements: Cell viability analysis

Abstract

Objective:The aim of the study was to assess, in vitro, the influence on cytotoxicity of heat treatment applied before photopolymerization, while mixing three self-adhesive resin cements, in an NIH/3T3 fibroblast cell culture, based on cell viability measures.Methods:Samples were divided into three groups: (1) no heat treatment while mixing (control), (2) 37°C, and (3) 60°C heat treatment while mixing. Cements were light-cured immediately after mixing and immersed in Dulbecco's Modified Eagle Media for the extraction of possibly uncured products after 24 h and 7 days. Cultures contained 0.5 mL of NIH/3T3 fibroblasts per well at a concentration of 0.4 × 105 cells/mL and specific extracts for each sample.Statistical Analysis Used:Data were statistically analyzed with ANOVA and post hoc Student–Newman–Keuls (significance of 5%).Results:Cement cytotoxicity increased with time, as shown by the higher values observed at 7 days. There was a slight difference in intragroup cytotoxicity levels between 24 h and 7 days. Heat treatment at 60°C was associated with a major decrease in cytotoxicity levels in all three groups, both at 24 h and at 7 days, with no differences among the cements.Conclusions:Heat treatment at 60°C should be considered as a strategy to reduce cytotoxicity of self-adhesive resin cements, as evidenced by the results observed at 24 h and 7 days of analysis.

Cytotoxic effects of different self-adhesive resin cements: Cell viability and induction of apoptosis

“…31 In agreement with our findings, other researchers also reported elevating cytotoxic effects with increasing exposure time to SARCs. [32][33][34] In a recent study, the cytotoxic effects of RU and BisCem (Bisco Inc.) SARCs on NIH/3T3 cells were examined, and it was detected that more cytotoxicity was encountered after 7 days of exposure than at the end of 24 h. 19 Besides, Pagano et al 35 reported that the cytotoxicity risk of a material was strongly related with the contact time, in agreement with the present study. Therefore, it may be suggested that resinbased restorative materials should be tested in both shortand long-term exposure periods.…”

“…On the other hand, various cell types are used for cytotoxicity studies. In our study, we preferred the permanent NIH/3T3 cell line, like many other studies, 19,22 as recommended by ISO 7405, 26 which showed similar cytotoxicity response to pulp-derived cells. 30 Moreover, NIH/3T3 cells can be easily reproduced and used for a large scale testing.…”

“…Despite all its ease of use and popularity, there are reservations about the biocompatibility of SARCs recently. [17][18][19][20][21] Thus far, the cytotoxicity of calcium-and fluoride-releasing contemporary SARCs has not been studied. Therefore, the aim of this in vitro study was to investigate the effects of four different SARCs on cell cultures using various testing methods: (1) extract testing, (2) cell culture inserts, and (3) dentin barrier testing.…”

Effect of various polymerization protocols on the cytotoxicity of conventional and self-adhesive resin-based luting cements

“…One disadvantage of the MTT assay is non-consistent estimation of number of viable cells in the resin content of tested materials [21] or the test itself [22] depending on the material tested, while several advantages of the test are obtaining rapid results, ease of application and visualization of cell density in small cell cultures [14,23,24]. In vitro studies that evaluated cytotoxicity of dental materials have commonly used fibroblast cells such as L929 and NIH/3T3 because of the reproducibility, availability and the resemblance of these cells to pulpal and gingival cells [1,6,[24][25][26][27]. Especially, NIH/3T3 which is one of the most commonly recommended cells for MTT assay, is a continuous cell line meaning that they can be reproduced fast and easy [26].…”

Effect of heat treatment on cytotoxicity and polymerization of universal adhesives

“…Resin components, for instance, are highly aggressive when in contact with cells: The literature reports a decrease in their aggressive behavior as soon as they are removed from the environment containing cells 14) . With the goal of improving polymer cross-linking and consequently increasing the rates of resinous polymer conversion, thus decreasing the number of residual monomers, some authors have proposed to increase photopolymerization time of resinous components 18,19) , whereas other authors have tested the use of external sources of heating before photopolymerization, within biologically acceptable limits [20][21][22][23][24][25] , resulting in immediate conversion gains, and also decreasing the concentration of final solvent in the adhesive system 26) . Temperatures of 23, 37, and 60ºC have been used to assess the mechanical properties of resinous compounds, and 60ºC has been reported to be the optimal temperature to improve polymer properties and system stability 20,22,26) .…”