Objective: To test the hypothesis that there is no difference between the frictional forces produced by a passive self-ligating bracket (SLB) in vitro and a conventional bracket (CB) used with two types of elastomeric ligatures. Materials and Method: The brackets, wires and ligation methods used in vitro were a passive SLB and a CB used with two types of elastomeric ligatures (conventional elastomeric ligature [CEL] and unconventional elastomeric ligatures [UEL]). The bracket ligation systems were tested with two types of wires (0.014Љ super elastic nickel titanium wire and 0.019Љ ϫ 0.025Љ stainless steel wire). Resistance to sliding of the bracket/wire/ligature systems was measured with an experimental model mounted on the crosshead of an Instron testing machine with a 10 N load cell. Each sample was tested 10 consecutive times under a dry state. Results: Frictional forces close to 0 g were recorded in all tests with SLB and in all tests with UEL on CB with both wire types. Resistance to sliding increased significantly (87-177 g) (P Ͻ .05) when CEL on CB was used with both wires. Conclusion: UELs may represent a valid alternative to passive SLBs for low-friction biomechanics.

The hypothesis is rejected, but the amount of chromium released in all test solutions was well below the daily dietary intake level.

Nanofilled FRCs showed significantly higher load values than conventional FRCs. Higher flexural strength values were recorded with 1-mm deflection for both FRC tested.

Nanofilled FRCs showed higher load values after additional oven postcuring.