不同尺寸多曲方丝弓在不同托槽系统中局部载荷挠曲率的实验研究

An experimental study of the regional load deflection rate of multiloop edgewise arch wire in two dimension brackets

目的测量并比较3种尺寸不锈钢方丝弯制的多曲方丝弓分别在2种托槽系统中不同牙位间的局部载荷挠曲率,分析多曲方丝弓的力学特性。方法分别用0.41mm×0.56mm、0.43mm×0.64mm、0.46mm×0.64mm型号的不锈钢方丝弯制多曲方丝弓(MEAW)弓丝中独立的"L"形曲。用电子万能材料试验机在室温下对各"L"形曲分别在上下颌不同牙位间进行加载和卸载实验,将0.41mm×0.56mm的"L"形曲固定于0.46mm×0.64mm的托槽(A托槽)中,0.43mm×0.64mm和0.46mm×0.64mm的"L"形曲固定于0.56mm×0.71mm的托槽(B托槽)中。各牙位间的待测弓丝分别取5个样本重复实验,测得各自的局部载荷挠曲率,数据用SPSS11.0软件包进行统计处理。结果0.41mm×0.56mm的"L"形曲在A托槽与0.43mm×0.64mm的"L"形曲在B托槽的不同牙位间的局部载荷挠曲率相比较,除在上颌1-2、下颌1-2和2-3二者间差异有统计学意义外(P<0.05),在其余牙位间,差异均无统计学意义(P>0.05)。0.41mm×0.56mm的"L"形曲在A托槽与0.46mm×0.64mm的"L"形曲在B托槽的不同牙位间的局部载荷挠曲率相比较,除在下颌6-7二者间差异无统计学意义外(P>0.05),在上下颌其余牙位间,二者间差异均有统计学意义(P<0.05)。结论在B托槽系统中用0.43mm×0.64mm不锈钢方丝弯制的MEAW弓丝,其力学性能与在A托槽系统中用0.41mm×0.56mm的不锈钢方丝弯制的MEAW弓丝相似。在临床应用时,可适当增减"L"形曲的长度,以提高矫治效能。

Objective To establish a stable mandibular fracture model with inferior alveolar nerve （IAN） mutilated for exploring the IAN influence to the expression of collagen Ⅰ during mandibular fracture. Methods Japanese white rabbits were selected and IAN was liberated. The right was leaven as it is and the left was cut off, then 2 mm×5 mm fracture model was made, and HE staining and chromotropic acid 2R-bright green staining and in situ hybridization of collagen Ⅰ mRNA were made to detect mandibular fracture healing and collagen Ⅰ mRNA expression. Results Fracture healing was smooth in IAN conserved side, but delayed in the IAN mutilated side. Collagen Ⅰ in situ hybridization showed that at one week and two weeks after surgery there were obvious differences between the two sides （P〈0.05）, but no difference at three weeks after surgery and four weeks （P〉0.05）. Conclusion The IAN could regulate mandibular fracture healing, and influence collagen Ⅰ mRNA earlier expression.