In vitro Streptococcus mutans and Candida albicans adhesion on clear orthodontic aligners exposed to artificial...

Considering the pathogenic potential of some bacteria and yeast species in oral cavity this study aimed to analyze the capability of Streptococcus mutans and Candida albicans in artificial saliva (AS) to form biofilm on clear aligners.

Clear aligners fragments (Invisalign™) were subjected to a 7-day biofilm formation experiment in AS and tryptic soy broth (TSB) with S. mutans or C. albicans pre-inoculated. TSB and AS cultures were evaluated for microbial growth and biofilm formation with crystal violet assay. Quantitative data were statistically compared using the Mann-Whitney test and the Pearson correlation. Also, fragments were qualitatively processed using scanning electron microscopy (SEM) images.

TSB induced the growth of S. mutans more effectively when compared to AS. Both media induced significant growth of C. albicans compared to biofilm, with TSB being significantly higher than AS. However, for both microorganisms, biofilm formation in AS and TSB did not show differences, indicating they may not depend on nutrients to adhere on clear aligners. SEM images showed bacteria and yeast cells adhering to the appliance's inner surfaces for both media.

Aligners cover tooth enamel and gingival tissues for a long time and can interfere with oral microbiota and human health. Recognizing the real capacity of bacteria and yeast species to adhere to the surface of new aligners is important for raising awareness among professionals and patients.