Adhesion of Streptococcus mutans on Different Types of Orthodontic Elastic O-rings

Objective: The aim of this study was to evaluate the adhesion of Streptococcus mutans (S. mutans) on different types of orthodontic elastic O-rings. Materials and methods: In vitro experiment, the adhesion of S. mutans on 4 types of elastic O-rings [3M Unitek (USA), Dynaflex (USA), Thai elastic (Thailand), W&H (China)] were investigated. The saliva-coated samples were immersed in a flat-bottomed 96-well plate containing S. mutans suspension (10(8) CFU/ml) and incubated at 37.0 with 10% CO2 for 2 hours at 100 rpm. The adhered bacterial cells were fixed by using 99% methanol, then stained with 0.5% crystal violet. The quantity of adhesion was determined by measuring optical density at 590 nm. Surface area of each sample was calculated by using the formula [surface area= pi(2) (R-2 - r(2))] and surface roughness was investigated by scanning electron microscopy. The data were analyzed with Kolmogorov-Smimov test, Levene test, one way ANOVA and Tukey HSD post hoc test. Results: High bacteria adhesion was found on 3M Unitek, whereas moderate adhesion was noted on Thai elastic and W&H. The lowest adhesion was found on Dynaflex. Conclusion: Surface area and surface roughness were factors that contributed to the amount of S. mutans adhesion on orthodontic elastic O-rings.