Evaluation of titanium dioxide coating on surface roughness of nickel-titanium archwires and its influence on Streptococcus mutans adhesion and enamel mineralization: A prospective clinical study

Abstract

This research aimed to evaluate the effect of titanium dioxide (TiO2) coating on surface roughness (Ra) of nickel-titanium (NiTi) archwires and its influence on Streptococcus mutans (S mutans) adhesion and enamel mineralization at the end of 1month in orthodontic patients and to evaluate the integrity of the TiO2 coating. Twelve patients undergoing orthodontic treatment with preadjusted edgewise appliance formed the sample for this prospective clinical study. Uncoated NiTi archwires and TiO2 nanoparticle coated NiTi archwires in as-received condition and after 1month of intraoral use were subjected to Ra analysis using surface profilometry, and surface topography using scanning electron microscopy. S mutans adhesion was evaluated on the retrieved archwires using real-time polymerase chain reaction (PCR). Enamel mineral content in the arches related to the uncoated and coated archwires was evaluated using DIAGNOdent. After 1month of intraoral use, both coated and uncoated archwires exhibited a rougher surface with coated archwires demonstrating greater quantum of increase (control, P=0.002; experimental, P=0.002). S mutans adhesion was more in uncoated archwires (P=0.0005). The TiO2 nanoparticle coating on the NiTi archwires showed delamination, deterioration and was lost by 60% at the end of 1month. Laser fluorescence values did not show any significant difference (control, P=0.182; experimental, P=0.105). TiO2 nanoparticle coating on NiTi archwires causes an initial reduction in roughness; however, at the end of 1month, the benefit was lost. S mutans adhesion was lesser on the coated wires, which could be attributed to reduced initial Ra and antibacterial property of TiO2. Orthodontic archwire appears to have a limited role in enamel demineralization.