Development of Orthodontic Resin with Antibacterial Property against Biofilm of Respiratory Pathogens

Orthodontic appliance made of resin is one of the main factors involving the shift of oral microbial community towards the source of pathogens by providing an extra site for adhesion and attachment of microorganisms to form biofilm associated with infections of multiple organs including respiratory tract. As a result, there is a demand for seeking of oral appliances with antimicrobial properties to reduce the risk of these infections. Here, vanillin (a principal flavoring agent with its antimicrobial property) has been incorporated to orthodontic resin and investigated the effect on biofilm formation of respiratory pathogens. The self-curing PMMA orthodontic resin samples (Siam Cement Group, Thailand) were fabricated depending on the percentage of vanillin adding (0.1% and 0.5% w/w vanillin). Resin without vanillin was used as a control. All samples were coated with sterile saliva collected from healthy volunteers. The bacterial biofilm formation assay was done by adding suspension (10 7 colony forming unit/mL) of Staphylococcus aureus ATCC 5638, Staphylococcus epidermidis ATCC 14990, Streptococcus pneumoniae ATCC 49619, and Pseudomonas aeruginosa ATCC 27853 to the samples and incubated in shaking incubator (120 r/min) for 120 min at 37 °C to allow the adhesion of the bacteria. Afterwards, non-adherent bacterial cells were washed out and Brain Heart Infusion broth was added and further incubated for 24 h to enable the biofilm formation. The amount of vital biofilm was quantified by Cell Counting Kit WST-8 (Dojindo Molecular Technologies, USA). It was found that the inclusion of vanillin to resin decreased the biofilm formation of S. aureus, S. epidermidis , and P. aeruginosa whereas no effect was observed on S. pneumoniae . Both the 0.1% and 0.5% vanillin concentrations could significantly inhibit the biofilm of S. aureus and P. aeruginosa whereas only 0.5% vanillin showed the inhibitory effect on S. epidermidis . Up to 40% biofilm reduction was noticed with S. epidermidis and P. aeruginosa while that of S. aureus was about 30%. In conclusion, the present data demonstrate that the development of orthodontic PMMA resin incorporated with vanillin may be a possible candidate for fabricating of oral appliance with antimicrobial property against respiratory pathogens. This suggests that it could be useful for the prevention or management of respiratory infection related to bacterial biofilm formed on oral appliances.