Comparative analysis of microorganism adhesion on coated, partially coated, and uncoated orthodontic archwires: A prospective clinical study.

INTRODUCTION: This study aimed to compare the microorganism adhesion on coated, partially coated, and uncoated orthodontic archwires after clinical use. The correlation between surface roughness (SR) and bacterial colonization was also evaluated. METHODS: A total of 48 archwire segments (0.016 x 0.022-in) were equally divided into 4 groups: nickel-titanium coated, nickel-titanium partially coated, uncoated stainless steel, and uncoated nickel-titanium. The archwires were randomly inserted in a split-mouth study design. After 4 weeks of clinical use, the total number of microorganisms adhering to the archwire was quantified and transformed into colony-forming units. SR was evaluated using a profilometer. A one-way and two-way ANOVA, post-hoc Tukey test, paired-samples t test, and Pearson correlation coefficient were used for statistical analysis. RESULTS: All the archwires presented microorganism adhesion, with the nickel-titanium-coated group demonstrating the highest value (P < 0.001). A statistically significant increase in SR was observed after clinical use for all groups (P < 0.05). No correlation between SR and bacterial adhesion was detected. CONCLUSIONS: Microorganism adhesion occurred on all of the archwires tested, especially on the esthetic fully coated. Because SR was not correlated with microorganism adhesion, future studies should evaluate the effect of surface free energy and superficial chemical changes on in-vivo microorganism adhesion.