납착 분위기에 따른 교정용 선재의 레이저 납착효과

Abstract

The electric welding and/or soldering with flame torch to make a hook or spring on orthodontic wires seemed to have insufficient strength, anti-corrosion, anti-discoloration, and set down resistance. In this study, tension-fracture load and micro-hardness of laser welded joint for stainless steel(SS), Cr-Co(CC), TMA(TM) and Ni-Ti(NT) wires were tested with universal testing machine and micro-hardness tester. The welding was done under air and argon(Ar)-gas atmospheres. The enegy intensity of Nd:YAG laser was changed and two diffenrent welding methods, butt and lap joints, were tested. The results were showed that tension-fracture loads of butt joint welded SS, CC and TM were increased with higher laser energy intensity in Ar-gas atmosphere compared to air atmosphere except 2J. In NT, 2, 4, and 10J were showed higher tension-fracture loads under Ar-gas atmosphere(P<0.005). In TM, tension-fracture load was increased with higher laser energy intensity under Ar-gas but decreased under air atmosphere. Tension-fracture loads of the lap joint welding were showed not significantly differences between air and Ar-gas atmospheres except 2J of 55 and 2 and 6J of CC (P<0.05). In TM, higher laser energy intensity groups were showed higher tension-fracture load under Ar-gas atmosphere. They were showed significant difference except in 4J group(P<0.05). NT also were showed higher result in Ar-gas atmosphere. They were showed joint failure in 8, 10, and 12J group under air atmosphere. The lesion-fracture load of 12J group of SS, CC and TM were showed the highest result. The micro-hardness of CC joint showed significantly lower result in atmosphere. SS and NT showed no significant differences. TM showed higher hardness under atmosphere. This study showed that SS, CC, and TM wires were seemed to be able to get sufficient laser welded joint under clinical condition.