Chemical and Mechanical Removal of Staphylococcus Aureus from Orthodontic Retainers

Aim. Recent studies have indicated that non-oral microorganisms are able to colonise intraoral devices such as orthodontic retainers. The aim of this study was to evaluate the effectiveness of chemical and mechanical elimination of Staphylococcus aureus biofilms (MRSA) from thermoplastic discs which were used to represent orthodontic retainers. Methods and Results. Methicillin-resistant Staphylococcus aureus biofilms were grown on 5mm diameter thermoplastic copolyester discs in a Constant Depth Film Fermentor (CDFF). The efficacy of biofilm removal by Corsodyl, Steradent Active Plus, Endekay and Retainer Brite solutions were compared to a saline control against 1 and 2 day old biofilms. The discs containing the MRSA biofilms were exposed to each solution for 10, 30 and 60 minutes. All 4 antimicrobial agents were able to significantly reduce the numbers of viable organisms within the biofilm with Corsodyl showing the highest reduction in each case. Mechanical intervention was also investigated by using a commercially available sonicator. The combination of using both an antimicrobial agent and sonication showed no significant difference when compared tousing the antimicrobial agent alone. Conclusion. This study shows that clorhexidine based mouthwash is the best chemical agent at reducing biofilm on the vacuum formed retainer, however residual microorganism retention could lead to re-growth and recolonisation. Therefore, it is essential to look at other methods of cleaning such mechanical means to enhance the effect of chemical elimination of biofilm.