Effect of the crystalline structure of ceramic orthodontic brackets on the adherence of Streptococcus mutans and Candida albicans: An in vitro study.

Background: With recent increases in demand for the esthetic aspects of orthodontic treatments, the use of ceramic brackets has gained more popularity. Dental demineralization is a frequent, undesired effect of microbial biofilm adhesion to orthodontic appliances. The crystalline structure of ceramics results in different material properties, and its possible effect on microbial adhesion was investigated in this study.

Materials and methods: This research was conducted experimentally and in vitro. Samples consisted of 40 monocrystalline and 40 polycrystalline brackets, further divided into two groups incubated with either Streptococcus mutans alone or S. mutans with Candida albicans. The culture medium was Tryptic Soy Broth with 20% sucrose. All samples were incubated at 37°C for 48 h. Macroscopic detachment of the formed biofilm would be the basis for adhesion scoring. The Mann-Whitney test was used to analyze the adhesion scores. In this study, a significance level of P < 0.05 was considered.

Results: The mean for adhesion score in S. mutans group was 1.85 ± 0.67 for the monocrystalline group and 2.35 ± 0.59 for the polycrystalline group (27% difference, P = 0.035). The adhesion score in S. mutans and C. albicans group was lower in the monocrystalline group (1.6 vs. 2.0) but was not statistically significant (P = 0.108).

Conclusion: This study showed that monocrystalline ceramic brackets had less overall microbial biofilm adhesion compared to polycrystalline ceramic brackets, especially when incubated with S. mutans alone. This observation might be explained primarily by lower surface roughness in monocrystalline ceramics.