The Influence of Gold, Rhodium, and Flexy Blue Titanium Esthetic Surface Coating of NiTi Archwire on Mutans Streptococci Adhesion: An In Vitro Study

Purpose: Orthodontic archwires play an important part in the enamel demineralization during orthodontic treatment. Dental caries is thought to be caused by the adhesion and colonization of mutans streptococci on these surfaces, followed by the formation of pathogenic plaque. This research was conducted with the purpose of testing and comparing the adhesion of mutans streptococci to a variety of aesthetic archwires as well as a conventional archwire made of NiTi. Materials and Methods: Four types of nickel-titanium archwires with round cross-section 0.016 inch were used in the current study, one type uncoated NiTi and three types of coated NiTi (rhodium, gold, and flexy blue). After two hours of agitation in 2 ml of sterile Unstimulated Whole Saliva (UWS), 5 pieces of each archwire were incubated in a streptococcus mutans suspension for 5-, 90-, and 180-minutes time interval. Bacterial adhesion was assessed by a microbial culture technique and the amount of bacterial adhesion was counted by colony forming unit. Results: There were no statistically significant differences in mutans streptococci adhesion among archwires at (90 and 180 minutes), while at 5 minutes, the mutans streptococci adhesion on gold-coated and rhodium-coated were significantly less than uncoated NiTi archwires. Conclusion: Clinical use of esthetic-coated archwires may provide the same risks for bacterial adhesion compared with uncoated conventional archwires and increased mutans streptococci adhesion was significantly related to longer incubation time.