Genotoxic and cytotoxic potential of methacrylate-based orthodontic adhesives

Abstract

Objectives The biocompatibility of methacrylate-based adhesives is a topic that is intensively discussed in dentistry. Since only limited evidence concerning the cyto- and genotoxicity of orthodontic adhesives is available, the aim of this study was to measure the genotoxic potential of seven orthodontic methacrylate-based adhesives. Materials and methods The XTT assay was utilized to determine the cytotoxicity of Assure Plus, Assure Bonding Resin, ExciTE F, OptiBond Solo Plus, Scotchbond Universal Adhesive, Transbond MIP, and Transbond XT after an incubation period of 24 h on human gingival fibroblasts. We also performed the γH2AX assay to explore the genotoxic potential of the adhesives within cytotoxic dose ranges after an incubation period of 6 h. Results The XTT assay showed a concentration-dependent reduction in cell viability. The decrease in cellular viability was in the same dose range most significant for Assure Plus, rendering it the adhesive material with the highest cytotoxicity. Employing the γH2AX assay, a concentration-dependent increase in H2AX phosphorylation was detected, indicating induction of DNA damage. Conclusions For most products, a linear correlation between the material concentration and γH2AX foci was observed. The most severe effect on γH2AX focus induction was found for Transbond MIP, which was the only adhesive in the test group containing the co-initiator diphenyliodonium hexafluorophosphate (DPIHP). Clinical relevance The data indicate that orthodontic adhesives, notably Transbond MIP, bear a genotoxic potential. Since the study was performed with in vitro cultivated cells, a direct translation of the findings to in vivo exposure conditions should be considered with great diligence.

The Cytotoxicity of OptiBond Solo Plus and Its Effect on Sulfur Enzymes Expression in Human Fibroblast Cell Line Hs27

“…The OptiBond family adhesive systems are one of the most widely used in dental practice [1]. Its effectiveness has been well described in caries inhibition in vitro [24,25] and its usage is being tested in current experiments [2,26]. We decided to investigate the cytotoxic effect and effect on cell number upon incubation with OptiBond Solo Plus, mostly because there is no consensus in the literature regarding the toxicity of dental adhesive systems toward dental pulp to date [2,27].…”

“…Its effectiveness has been well described in caries inhibition in vitro [24,25] and its usage is being tested in current experiments [2,26]. We decided to investigate the cytotoxic effect and effect on cell number upon incubation with OptiBond Solo Plus, mostly because there is no consensus in the literature regarding the toxicity of dental adhesive systems toward dental pulp to date [2,27]. In our study, the cytotoxic effect was demonstrated for the concentration of 0.03% after both incubation times, while the reduced number of cells was registered in a dose dependent manner, visibly observed in the microscopic picture.…”

“…The literature search was also involved in the process of the proper dilution determination. The information regarding the in vitro cellular model of OptiBond Solo Plus certain dilutions were taken into consideration [2,15].…”

“…They are used for bond restoration with dentin and enamel and the proper bonding strength can be achieved only when those systems are polymerized properly. In orthodontic treatment, the bonding process poses a threat of monomers coming into direct contact with the living tissue within the oral cavity [1][2][3]. Incomplete polymerization of dental adhesives can be a source of these monomers.…”

“…In the cited in vitro study, the authors demonstrated that most of adhesive resins used in orthodontics and available on the European market release biologically harmful substances to the immediate environment [10]. Therefore, the clinical verifiability of widely used dental bonding systems including OptiBond Solo Plus is still necessary, as despite their postulated harmful effect on living tissues, these materials are still used in everyday clinical dental practice [2]. The studies on new polymerization and filling strategies for dental composites in a mouse model demonstrated that composite materials are also indicated as possibly being highly cytotoxic, exhibiting detrimental effects on cells [11,12].…”