Cytotoxicity and genotoxicity of orthodontic bands after aging: an in-vitro study

This investigation sought to evaluate cytotoxic and genotoxic effects of two different types of orthodontic bands after aging in acidic and neutral artificial saliva using human gingival fibroblast-like (HGF1-PI 1) cell lines.

Two commercial brands of orthodontic molar bands (American orthodontic (AO) and 3 S-dental bands), commonly used by orthodontists, were tested. These bands were divided into four groups to examine the effects of aging following thermocycling, and pH variations (pH = 4.5 and pH = 7.4). Cytotoxicity was assessed using the MTT assay. Comet assay was used to evaluate genotoxicity.

Our results demonstrated that AO molar bands exhibited significant cytotoxic effect on gingiva cells following incubation in acidic condition compared to untreated control (P = 0.04), however no effect was observed at neutral condition. In contrast, 3 S-dental molar bands showed no significant differences at both conditions compared to control group. Regarding genotoxicity, DNA damage was evident for both brands at pH = 4.5, however, AO molar bands demonstrated longer comet tails compared to 3 S-dental molar bands. AO molar bands was also showed relatively DNA destruction at pH 7.4, while no genotoxicity was for 3 S-dental molar bands.

The results collectively showed that AO molar bands exhibited cytotoxicity only at acidic pH, while 3 S-dental molar bands showed no cytotoxic effects at either acidic or neutral conditions. Additionally, AO molar bands demonstrated greater genotoxicity than 3 S-dental molar bands at both pH levels. These data represented acceptable biocompatibility for both bands in neutral conditions. However, AO bands seem to become toxic for gingiva cells in acidic milieu.