Archwire cleaning after intraoral ageing: the effects on debris, roughness, and friction

Dental material science has paid more attention to mechanical properties of as-received materials than to changes produced after intraoral exposure. Orthodontic archwires when exposed to the intraoral environment have shown a significant increase in the degree of debris, surface roughness (Ra), and frictional force. The purpose of this split-mouth study was to evaluate the effects of two methods of archwire cleaning on these variables after clinical use for 8 weeks. For eight individuals, four sets of three brackets each (n = 32) were bonded from the first molar to the first premolar. A passive segment of 0.019 × 0.025 inch stainless steel (SS) archwire was inserted into the brackets and tied by elastomeric ligature. Debris level [via scanning electron microscopy (SEM)], Ra, and frictional force were evaluated in a paired comparison after 8 weeks of intraoral exposure and after cleaning with a steel wool sponge (SWS) for 1 minute or ultrasound (US) cleaning for 15 minutes. Kruskal-Wallis, Friedman's, and Spearman and Pearson correlation tests were used for statistical analysis. The debris and Ra of SS rectangular wires increased significantly (P < 0.05) during clinical use, causing a significant increase in the frictional force level. These changes can be effectively eliminated by either of the investigated cleaning methods, although a SWS seems to be clinically more practical.