Effects of cold chemical (glutaraldehyde) versus autoclaving sterilization on the rate of coating loss of aesthetic archwires: A double-blind randomized clinical trial

Summary Objective The effect of any sterilization methods (cold chemical, or hot) on film removal from coated archwires has not yet been investigated. Thus, we assessed it. Materials and methods This double-blind randomized clinical trial was performed on 120 observations: 40 macroscopically intact coated archwires from 4 brands were purchased (n = 10 archwires/brand). Five wires from each brand underwent cold and 5 underwent hot sterilization. Wires were applied in 40 non-extractions patients at alignment phase of treatment (one month). Afterwards, 3 inter-bracket segments from each wire were examined microscopically, and the percentage of coating loss was recorded for each segment. Coating losses of the 4 brands and 2 sterilization methods were compared using a two-way ANOVA and a Welch t-test (α = 0.05). Surfaces were also evaluated using scanning electron microscopy. Results The mean surface coating loss of hot (autoclave) and cold (glutaraldehyde) sterilization methods was 25.6 ± 28.7 and 28.1 ± 30.8 percent respectively. The mean surface coating removal of the Ortho Organizers, American Orthodontics, SIA, and Gestenco brands were 24.1 ± 28.4, 36.7 ± 36.0, 23.0 ± 24.4, and 23.6 ± 28.0 percent, respectively. The two-way ANOVA indicated a lack of overall significant differences among wire brands (P = 0.189) and between sterilization types (P = 0.629). However, the interaction of sterilization and brands was significant (P = 0.005). Conclusions Within the limitations of this 1-month clinical trial limited to 4 coated NiTi archwire brands only, the average coating removal of examined brands might not differ much, amounting to about 26% within a month. Glutaraldehyde and autoclave sterilization might not affect the average speed of coating loss in all brands, although each sterilization method might be favourable for certain brands.