Resistance to Sliding of Orthodontic Archwires Under Increasing Applied Moments

Objectives: Orthodontic treatment with fixed appliances involves sliding of brackets along archwires. These movements involve friction, which causes resistance to sliding. In addition, moments are created as teeth tip until binding occurs between the bracket and archwire. A newly developed TiMolium archwire promises material properties superior to β-Titanium paired with smoother surface finish, potentially leading to reduced resistance to sliding and shorter treatment times. This study compared TiMolium archwires with ß-Titanium and stainless steel archwires as the current gold standard under application of an increasing moment.
Methods: A total of 120 stainless steel (Smartclip, 3M, Monrovia, CA) and ceramic self-ligating 0.022”-slot brackets (Clarity SL, 3M) were divided into six equal-sized groups. Resistance to sliding was tested with 0.019x0.025” TiMolium (TP Orthodontics, La Porte, IN), β-Titanium (3M), and stainless steel (3M) archwires using a custom-designed apparatus to simulate sliding mechanics and application of moments of 1000, 2000, and 3000 g-mm. This experimental design, which relates resistance to sliding to the magnitude of moment applied, allowed for clinically relevant comparison of the materials. Differences in resistance to sliding among groups were tested for statistical significance using Kruskal-Wallis ANOVA with P<0.05 considered statistically significant.
Results: Using stainless steel brackets, the TiMolium archwires had significantly higher resistance to sliding than stainless steel archwires at all moments tested while there was no significant difference between TiMolium and β-Titanium. Using ceramic brackets, the resistance to sliding with TiMolium archwires was no different than with stainless steel archwires at all moments tested. Both TiMolium and stainless steel archwires showed significantly lower resistance to sliding than β-Titanium.
Conclusions: TiMolium archwires show resistance to sliding intermediary to stainless steel and β-Titanium archwires when clinically relevant moments are applied. Used with stainless steel brackets, they behave like β-Titanium, whereas used with ceramic brackets, they behave like stainless steel.