A Comparison of the Sliding Properties of Titanium Brackets with Reduced Friction Stainless Steel Brackets

The use of titanium as an alternative to nickel containing appliances for orthodontic applications has only recently occurred. It was Introduced to the field or orthodontics as a result of reports jn the literature of type IV hypersensitivity reactions to the nickel released from stainless steel orthodontic appliances. It was observed that the frictional properties of titanium brackets were similar if not superior to those of stainless steel brackets. A review of the literature reveals that the results of recent studies comparing the frictional properties of titanium vs. stainless steel brackets are comparable. Some studies have concluded that the difference in frictional properties of the two bracket materials is not significant. The development of reduced friction design with the stainless steel brackets has also led to a significant reduction in the frictional properties of these brackets. No study has compared the frictional properties of titanium brackets with reduced friction, sintered stainless steel brackets in the passive configuration. The purpose of this study was to evaluate the static and kinetic frictional force values of a commercially pure titanium bracket and compare them to those of a reduced friction, sintered stainless steel bracket using an in vitro experimental design. Specially designed testing fixtures were used to simulate the setup of a test bracket and wire as they would occur clinically. An lnstron universal testing machine was used to measure the mean static and kinetic frictional forces produced for nine different bracket/arch wire combinations. The brackets tested included a commercially pure titanium bracket, a standard stainless steel bracket and a reduced friction stainless steel bracket. The three sizes of arch wires tested were 0.019 x 0.025, 0.017 x 0.025 and 0.016 x 0.022 inch stainless steel. The data were subjected to a two-way analysis of variation (ANOVA) using SPSS software to identify the presence of possible, significant differences between the friction values. Tukey ad hoc multiple comparison test was used to locate the wires and brackets that were significantly different. The results of this study showed that mean static frictional force values were typically lower than the mean kinetic frictional force values within each bracket/arch wire combination. The titanium brackets showed the highest mean static frictional force values. Stainless steel brackets showed greater friction force values for the two largest wire sizes. For the smallest wire size. titanium brackets showed greater friction when compared to stainless steel. All of the three wire sizes showed significantly lower frictional force values for the reduced friction stainless steel brackets