Experiment Study Of The Heat Treatment Effect On Load/Deflection Stress Of Different Reverse-curve Archwires

Objective:This study is to evaluate the load and deflection stress of 0.018-inch stainless steel round wires formed 2mm,4mm,6mm reverse-curve archwire before and after heat-treatment, and observe the change of load and deflection stress after 4 weeks.Method:12cm 0.018-inch stainless steel round wires were formed to 2mm,4mm,6mm reverse-curve archwires,totally 300 wires. Then evaluate and compare the load and deflection stress of heat-treated group wires and non-treated group. During 4 weeks retaintion, repeat the evaluation every week.Results:(1)The initial load and deflection stress in 2mm,4 mm and 6 mm heat-treated group are stastically significantly more than non-treated group(P<0.05),the differences of the initial load and deflection stress between 2mm,4 mm and 6 mm are stastically significant(P<0.05).(2)After 4 weeks retaintion, the load and deflection stress of all groups differ from initial evaluation stastically significantly(P<0.05)(.3)The differences of load and deflection stress decreasement between heat-treated group and non-treated group in 2mm and 4 mm are stastically significant(P<0.05),but in 6 mm is not stastically significant(P>0.05).Conclusions:(1)The initial load and deflection stress in 2mm,4 mm and 6 mm heat-treated group are stastically significantly more than non-treated group(P<0.05),the differences of the initial load and deflection stress between 2mm,4 mm and 6 mm are stastically significant(P<0.05)(.2)The load and deflection stress increase along with the depth of reverse-curve archwire.(3)The differences of load and deflection stress decreasement between heat-treated group and non-treated group in 2mm and 4 mm are stastically significant(P<0.05),but in 6 mm is not stastically significant(P>0.05).