Bacterial and fungal colonization on metallic and ceramic orthodontic brackets: A scanning electronic microscopy study

Universally, aesthetic smiles are common desires among people and can be achieved through orthodontic braces. In the human mouth, as well as on the surface of the teeth,a plentiful microbial community coexists, characterizing the biofilm. The aim of this study was to verify the pattern of bacterial (Streptococcus mutans and Lactobacillus spp.) and fungal (Candida albicans) colonization on metallic and ceramic brackets (3M Unitek). Partial fixed appliance were installed in 18 patients and two plaque collections were made: first - directly from dental surface; second - 21 days after bonding procedures, from brackets surfaces. Specific laboratory tests were carried out and for the fulfillment of the macroscopic reading, plates that presented from 30 to 300 colonies were selected. Scanning electron microscopy (SEM) examinations were performed on the surface of the brackets after 28 days of the experiment. S. mutans were the prevalent microorganisms, followed by Lactobacillus spp. and C. albicans. No obvious pattern of microorganism colonization favoring one bracket material over the other was found. Positive correlation was observed on the presence of Candida albicans between the initial condition and after braces insertion in the mouth. SEM showed heterogeneous distribution forms of cocci, bacilli, yeasts and filamentous fungi in the three areas delimited for visualization on bracket surface. All species investigated were present on the braces and we concluded that there is no difference when comparing ceramic and metallic brackets. Microorganisms did not show sites of preference in colonization, however, the slot areas presented greater accumulation.