目的:比较断冠再接和复合树脂直接修复两种方法修复前牙冠折后剪切力的差异。方法:制备恒上颌中切牙不累及髓腔的冠折模型36个,随机分为A、B组(n=18),A组采用自酸蚀粘结剂Clearfil SE Bond进行断冠再接,B组采用Clearfil SE Bond和复合树脂Clearfil AP-X进行直接修复。修复24 h后置于万能试验机加载台上,持续加载、直至折断,并记录折断时的力值。结果:断冠再接和复合树脂直接修复后的剪切力(N)分别为326.78±70.66和351.74±54.11(t=1.190,P=0.242)。结论:断冠再接和复合树脂直接修复两种方法修复前牙冠折后剪切力无明显差异。
When mono\|dispersed polypropylene was recovered from liquid paraffin, a solvent of large molar size, at a concentration more than \%C\%\+*, partially disentangled polypropylene was obtained. The modified polypropylene has a relatively high crystallinity. Furthermore, it has a lower apparent viscosity(\%η\%\-a) and shear stress\%(τ\%) than that of the control samples at the same shear rate\%(γ). \%The mechanical properties of the modified polypropylene are almost unchanged, which cannot be found in any other method of modifying the rheological properties of polymer.
