HL－3型颊侧多曲簧模拟口腔开闭口运动的抗疲劳断裂实验

Fatigue rupture study of HL-3 Buccal Multiloops for simulation of oral movements

背景:针对临床颊侧多曲簧活动矫治器中HL-1及HL-2型颊侧多曲簧易断裂的问题,研制了HL-3型颊侧多曲簧。目的:通过颊侧多曲簧仿真模拟试验仪模拟口腔开闭口运动,比较在相同条件下HL-2及HL-3型颊侧多曲簧的抗疲劳断裂强度。方法:将HL-2及HL-3型颊侧多曲簧固定在颊侧多曲簧仿真模拟试验仪上,位置模拟口腔内相应位置,两侧大小、高度、方向完全对称,开动仪器开始模拟口腔开闭口运动直至任意一侧颊侧多曲簧出现断裂并计录此时开闭口循环次数;通过扫描电镜观察断裂颊侧多曲簧的断口形貌特征。结果与结论:HL-3型颊侧多曲簧的开闭口循环次数明显多于HL-2型颊侧多曲簧(P<0.01),说明HL-3型颊侧多曲簧与HL-2型颊侧多曲簧相比具有更强的抗疲劳断裂强度;扫描电镜观察结果示,HL-2型颊侧多曲簧和HL-3型颊侧多曲簧断口均有明显的疲劳断裂特征,证明HL-2型颊侧多曲簧与HL-3型颊侧多曲簧的断裂均属于疲劳断裂;但在HL-3型颊侧多曲簧疲劳断口上可观察到较HL-2型大的裂纹区,并在断裂纹中可见磨合区,表明HL-3型颊侧多曲簧相对减少了多曲簧出现疲劳断裂的概率,延长了疲劳断裂时间。

BACKGROUND：Concerning the problem of the ruptured phenomenon in clinic work of HL-1 and HL-2 Buccal Multiloops removable appliance, we invented HL-3 Buccal Multiloops. OBJECTIVE：Through the Buccal Multiloops Fatigue Testing Machine which can imitate oral movements, to compare the fatigue strength of the HL-2 and HL-3 Buccal Multiloops in the same condition. METHODS：A pair of the HL-2 or HL-3 Buccal Multiloops with the completely symmetrical size, symmetrical height and symmetrical direction was fixed on the Buccal Multiloops Fatigue Testing Machine which could simulate oral movements, then keep the Buccal Multiloops Fatigue Testing Machine working until any Buccal Multiloops broke. The cyclic loading times of this pair Buccal Multiloops was recorded. Scanning electron microscope was used to observe the appearance of broken end of the Buccal Multiloops. RESULTS AND CONCLUSION：The cyclic loading times of HL-3 Buccal Multiloops were more than HL-2 Buccal Multiloops （P 〈 0.01）, suggesting that HL-3 Buccal Multiloops has stronger fatigue strength than HL-2 Buccal Multiloops. Scanning electron microscope observation showed that the fractures of HL-2 and HL-3 Buccal Multiloops al had the typical fatigue fracture morphology, indicating that the rupture of HL-2 and HL-3 Buccal Multiloops belongs to fatigue fracture. However, HL-3 Buccal Multiloops exhibited bigger crack compared with HL-2 Buccal Multiloops, the presence of running-in region, suggesting that HL-3 Buccal Multiloops reduced the probability of fatigue fracture and prolonged the time of fatigue fracture.