Autor: |
Sims, A. P. T., Waters, N. E., Birnie, D. J. |
Zdroj: |
Journal of Orthodontics; November 1994, Vol. 21 Issue: 4 p367-373, 7p |
Abstrakt: |
Friction in fixed appliance systems has received considerable attention in recent literature, although that attributable to varying second order (tip) and third order (torque) adjustments in either the bracket or the archwire has not been fully investigated. The ex vivo study of 0·022 × 0·028-inch slot Minitwin®, Activa®, and Standard Straight Wire®brackets investigates friction when known values of tip or torque were applied to 0·018 × 0·025-inch stainless steel wires. The resistance to sliding of the wire through the ligated brackets was measured on a vertically-mounted Instron testing machine.The results showed that the self-ligating Activa®brackets consistently produced less friction than the other conventionally tied brackets. Minitwin®brackets were slightly more resistant to movement than the Standard®brackets during torquing, but the converse was found when tip was applied. Increasing tip and torque (ranges tested 0–6 degrees and 0–25 degrees, respectively) produced almost linear increases in friction for all brackets, although increasing tip had the more profound effect on friction, particularly in Activa brackets. |
Databáze: |
Supplemental Index |
Externí odkaz: |
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