论文部分内容阅读
目的:评价循环加载对正常牙及不同程度氟斑牙牙本质微拉伸粘结强度的影响。方法:24个新鲜拔除的无龋第三磨牙和氟斑磨牙根据Dean氏指标分为正常、轻度、中度、重度4组。垂直牙体长轴除去冠部釉质,在面制备盒形洞,用Prime&BondNT粘结,复合树脂充填。每组再随机分成实验组和对照组,实验组以50N大小的力进行循环加载,加载10000次。制备测试微拉伸粘结强度的条状试件,在拉力试验机上测定粘结强度。结果:对照组中正常组、轻度组、中度组、重度组的微拉伸粘结强度分别为:(43.98±6.28)MPa、(39.83±8.70)MPa、(29.41±5.76)MPa、(19.61±4.15)MPa;加载组中正常组、轻度组、中度组、重度组的微拉伸粘结强度分别为:(35.13±7.81)MPa、(30.53±8.47)MPa、(21.66±6.51)MPa、(13.93±4.90)MPa。结论:循环加载10000次使所有粘接试件的微拉伸粘结强度下降;无论加载与否,粘接强度都随着牙齿氟化程度增加而降低,其中以重度氟斑牙组的粘接强度最低。
Objective: To evaluate the effect of cyclic loading on microtensile bond strength of normal dentine and dental fluorosis. METHODS: Twenty-four fresh caries-free third molar and freckle molars were divided into four groups according to Dean’s index: normal, mild, moderate and severe. The vertical mandibular long corneas were removed from the crown enamel, and a box-shaped hole was made in the facets. The resin was filled with composite resin with Prime & BondNT. Each group was then randomly divided into experimental group and control group. The experimental group was looped with a force of 50N and loaded 10000 times. A strip test piece for testing microtensile bond strength was prepared and the bond strength was measured on a tensile tester. RESULTS: The microtensile bond strengths of the normal group, mild group, moderate group and severe group in control group were (43.98 ± 6.28) MPa, (39.83 ± 8.70) MPa and (29.41 ± 5.76) MPa, respectively 19.61 ± 4.15) MPa. The microtensile bond strengths of normal group, mild group, moderate group and severe group were (35.13 ± 7.81) MPa, (30.53 ± 8.47) MPa, (21.66 ± 6.51) ) MPa, (13.93 ± 4.90) MPa. CONCLUSION: The microtensile bond strength of all the bonded specimens decreased with the cyclic loading of 10000 times. The bonding strength decreased with the increase of dental fluoridation regardless of loading or not. Among them, The lowest strength.