Assessment of antibacterial and cytotoxic effects of orthodontic stainless steel brackets coated with different phases of titanium oxide: An in-vitro study

Introduction: Our objective was to assess the antibacterial and cytotoxic effects of orthodontic stainless steel brackets coated with different phases of photocatalytic titanium oxide. Methods: From a total sample of 115 brackets, 68 orthodontic stainless steel brackets were coated with titanium oxide using a radiofrequency magnetron sputtering machine. The coated brackets were then converted into 34 each of the anatase and rutile phases of titanium oxide. These brackets were subdivided into 4 groups for antibacterial study and 3 groups for cytotoxicity study. Brackets for the antibacterial study were assessed against the Streptococcus mutans species using microbiologic tests. Three groups for the cytotoxicity study were assessed using the thiazolyl tetrazolium bromide assay. Results: The antibacterial study showed that both phases were effective, but the rutile phase of photocatalytic titanium oxide had a greater bactericidal effect than did the anatase phase. The cytotoxicity study showed that the rutile phase had a greater decrease in viability of cells compared with the anatase phase. Conclusions: It is recommended that orthodontic brackets be coated with the anatase phase of titanium oxide since they exhibited a significant antibacterial property and were only slightly cytotoxic.