Abstract
Fixed orthodontic appliances may lead to biofilm accumulation around them that may increase caries risk. This study aimed to evaluate the influence of quaternary ammonium methacrylates (QAMs) on the physicochemical properties, cytotoxicity, and antibacterial activity of adhesive resins for orthodontic purposes.Methodology:A base resin was prepared with a comonomer blend and photoinitiator/co-initiator system. Two different QAMs were added to the base adhesive: dimethylaminododecyl methacrylate at 5 wt.% (DMADDM) or dimethylaminohexadecyl methacrylate (DMAHDM) at 10 wt.%. The base adhesive, without QAMs, (GC) and the commercial Transbond™ XT Primer 3M (GT) were used as control. The resins were tested immediately and after six months of aging in the water regarding the antibacterial activity and shear bond strength (SBS). The antibacterial activity was tested against Streptococcus mutans via metabolic activity assay (MTT test). The groups were also tested for the degree of conversion (DC) and cytotoxicity against keratinocytes.Results:The resins containing QAM showed antibacterial activity compared to the commercial material by immediately reducing the metabolic activity by about 60%. However, the antibacterial activity decreased after aging (p<0.05). None of the groups presented any differences for SBS (p>0.05) and DC (p>0.05). The incorporation of DMADDM and DMAHDM significantly reduced the keratinocyte viability compared to the GT and GC groups (p<0.05).Conclusion:Both adhesives with QAMs showed a significant reduction in bacterial metabolic activity, but this effect decreased after water aging. Lower cell viability was observed for the group with the longer alkyl chain-QAM, without significant differences for the bonding ability and degree of conversion. The addition of QAMs in adhesives may affect the keratinocytes viability, and the aging effects maybe decrease the bacterial activity of QAM-doped materials.
Highlights
Fixed orthodontic treatment leads to significant caries risk due to biofilm accumulation around the appliance components and the challenges to achieve a reliable oral hygiene.1-5 During orthodontic bonding procedures, the excess of adhesive is invariably left on the tooth surface at the bracket-enamel interface
The groups containing dimethylaminohexadecyl methacrylate (DMAHDM) or DMADDM showed around 60 % lower metabolic activity compared to GT in T0, with a statistically significant difference between DMADDM and GT to GC (p0.05)
After six months of aging in distilled water (T1), the biofilms formed on the samples with DMAHDM or DMADDM showed higher metabolic activity compared to the immediate analysis (T0) (p
Summary
Fixed orthodontic treatment leads to significant caries risk due to biofilm accumulation around the appliance components and the challenges to achieve a reliable oral hygiene. During orthodontic bonding procedures, the excess of adhesive is invariably left on the tooth surface at the bracket-enamel interface. The excess of adhesive is invariably left on the tooth surface at the bracket-enamel interface. This adhesive excess may be a site for rapid attachment and growth of oral microorganisms such as Streptococcus mutans.. Demineralization occurs when the oral environment pH favors calcium and phosphate ions out of enamel, and early lesions appear clinically as opaque white spots caused by mineral loss.. White spot lesions (WSL) are one of the most common adverse effects of orthodontic treatment, occurring in almost 50 % of patients during the first year of treatment and may negatively affect dental esthetics.. Preventive approaches during orthodontic treatments have not been effective, and the occurrence of WSL is positively and significantly associated with the duration of the therapy. This adhesive excess may be a site for rapid attachment and growth of oral microorganisms such as Streptococcus mutans. Demineralization occurs when the oral environment pH favors calcium and phosphate ions out of enamel, and early lesions appear clinically as opaque white spots caused by mineral loss. White spot lesions (WSL) are one of the most common adverse effects of orthodontic treatment, occurring in almost 50 % of patients during the first year of treatment and may negatively affect dental esthetics. preventive approaches during orthodontic treatments have not been effective, and the occurrence of WSL is positively and significantly associated with the duration of the therapy.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
