Evaluation of titanium brackets for orthodontic treatment: Part II - The active configuration

After each archwire was ligated into a bracket with a 0.010-in stainless st eel wire, both stainless steel and beta-titanium archwires (0.017- x 0.025- in) were slid through commercially pure titanium brackets (0.018-in slot si ze) at 34 degrees C in both the dry and wet conditions. As controls, stainl ess steel archwire versus stainless steel bracket couples were used with co mparable dimensions. The drawing forces were measured at 5 angulations (0 d egrees, 3 degrees, 7 degrees, 9 degrees, and 11 degrees) for 5 normal force s (nominally 0.2, 0.4, 0.6, 0.8, and 1.0 kg). Regression lines were determi ned for each frictional couple (P < .05). In the passive configuration, the kinetic frictional coefficients of control and test couples in the dry con dition were comparable to previously reported Values at 0.11 +/- 0.01 for s tainless steel versus stainless steel, 0.12 +/- 0.00 for stainless steel ve rsus titanium, and 0.26 +/- 0.02 for beta-titanium versus titanium. As the angulation was increased from <degrees> to 11 degrees and the normal force was maintained at 0.2 kg, the resistance to sliding values increased by 208 g for stainless steel versus stainless steel, by 222 g for stainless steel versus titanium, and by 185 g for beta-titanium versus titanium. When the normal force was increased to 1.0 kg, the resistance to sliding values incr eased to 277 g, 246 g, and 245 g, respectively. Although resistance to slid ing increased with angulation and normal force, the passive layer did not b reakdown. Titanium brackets remained comparable to stainless steel brackets in the active configuration.