The purpose of this study was to investigate the change of 3 point bending properties of various nickel titanium wires after recycling. Four types of nickel-titanium (Align: martensitic type, NiTi, Optimahoy, Sentalloy austenitic type) wires were divided to three groups: as-received condition (TO: control group), treated in artificial saliva for four weeks (TI) and autoclaved after being treated in artificial saliva (T2). Detrimental changes were observed for the selected mechanical properties in three point bending test. Loading force at 3mm deflection, unloading force at 3mm deflection, stress hysteresis, loading force at Imm deflection, unloading force at 1 mm deflection and stress hysteresis at 1mm deflection were calculated.
The findings suggest that :
1. Align demonstrated statistically significant increase in loading force (p<0.05) and unloading force (p<0.01) at 3mm
deflection after recyycling(T2), but NiTi, Optimalloy and Sentalloy showed no statistically difference after recycling. 2. Align demonstrated statistically significant decrease in hysteresis(p<0.01) after recycling(T2) but NiTi, Optimalloy and
Sentalloy showed no statistically significant difference after recycling.
3. All wires showed no statistically significant difference in loading force at 1mm deflection, after recycling(T2).
4. Align demonstrated statistically significant decrease in unloading force in lmm deflection (p<0.05) after recycling(T2) but NiTi, Optimalloy and Sentalloy showed no statistically difference after recycling. .
5. Loading force and unloading force of Ti showed no significant change compared with those of TO, but loading force and unloading force of T2 showed significant changes´ compared with those of TO(p<0.05, p<0.01 respectively).
6. Align demonstrated a tendency to lose some of this pseudoelsticity in TI and pseudoplasticity and pseudoelasticity in T2.
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