The purpose of this study was to measure and compare the level of frictional resistance generated from three currently used ceramic brackets; 1, Crystaline V(R), Tomy International Inc., Tokyo, Japan; 2, Clarity(R), 3M Unitek, Monrovia, CA, USA; 3, Inspire(R), Ormco, Orange, CA, USA; with composite resin brackets, Spirit(R), Ormco, Orange, CA, USA; and conventional stainless steel brackets, Kosaka(R), Tomy International Inc., Tokyo, Japan used as controls. In this experiment, the resistance to sliding was studied as a function of four angulations (0 degrees, 5 degrees, 10 degrees, and 15 degrees) using 2 different orthodontic wire alloys: stainless steel (stainless steel, SDS Ormco, Orange, CA, USA), and beta-titanium (TMA, SDS Ormco, Orange, CA, USA). After mounting the 22 mil brackets to the fixture and .019 x .025 wires ligated with elastic ligatures, the arch wires were slid through the brackets at 5 mm/min in the dry state at 34 degrees C. Silica-insert ceramic brackets generated a significantly lower frictional force than did other ceramic brackets, similar to that of stainless steel brackets. Beta-titanium archwires had higher frictional resistance than did stainless steel, and all the brackets showed higher static and kinetic frictional force as the angulations increased. When the angulation exceeded 5 degrees, the active configuration emerged and frictional force quickly increased by 2.5 to 4.5-fold. The order of frictional force of the different wire-bracket couples transposed as the angle increased. The silica-insert ceramic bracket is a valuable alternative to conventional stainless steel brackets for patients with esthetic demands.