Objective:To evaluate the effect of three different types of dental rotary instruments on dentin surface properties during tooth preparation.Methods:42 freshly extracted human third molars with complete dentin crowns were selected.The occlusal enamel was removed to expose the surface of middle dentin.The teeth were randomly assigned to three groups,according to the rotary burs used including diamond-fine,diamond-medium and carbide-fine.The three rotary burs chosen for tooth preparation showed similar configurations in terms of taper,diameter,and tip shape.Dentin surfaces were prepared,and surface morphology of the specimen was observed.Surface roughness and surface contact angle were measured.Statistic analysis on the measurements was performed.Results:The effect of different instruments during preparation on dentin surface roughness was statistically significant (P＜0.001).The surface roughness for the diamond-medium group was the highest (Ra=5.97± 1.65 μm,Rz=41.23± 4.55 μm),followed by the diamond-fine group (Ra=2.82± 0.55 μm,Rz=21.49± 2.52 μm),the carbide-fine group was the lowest (Ra=1.4410.34 μm,Rz=10.54± 1.80 μm).The difference of the surface contact angle of the three groups was statistically significant (P＜ 0.001).The contact angle of the carbide-fine group was the lowest (First=48.67± 3.62°,Second=47.52±2.56°).The difference between the diamond-medium group (First=59.77± 6.70°,Second=59.32± 4.05°) and the diamond-fine group (First=62.33± 7.01 °,Second=61.33± 6.23°) was not significantly different (P＞0.05).Conclusion:compared with diamond burs,dentin surface prepared with carbide burs showed more smooth,and has higher surface wettability,more even smear layer and less smear layer debris.%目的:研究三种不同类型钻针牙体预备对预备体牙本质表面特性的影响.方法:选用42颗新鲜拔除的完整的人第三磨牙,去除颌面釉质,制备牙本质平面试件.将试件随机分为三组,分别使用形态、直径相同的三种钻针:磨光用金刚砂钻针、初预备用金刚砂钻针和磨光用钨钢钻针进行牙本质表面预备.观察预备后牙本质表面形态,测量牙本质表面粗糙度和表面接触角,并对测量结果进行统计学分析.结果:不同钻针预备对牙本质表面粗糙度的影响具有统计学意义(P＜0.001),初预备金刚砂钻针组的粗糙度最大(Ra=5.97±1.65μm,Rz=41.23±4.55μm),其次为磨光用金刚砂钻针组(Ra=2.82±0.55μm,Rz=21.49±2.52μm),磨光用钨钢钻针组粗糙度最小(Ra=1.44±0.34μm,Rz=1 0.54±1.80μmh不同钻针预备对牙本质表面接触角的影响具有统计学意义(P＜0.001),磨光用钨钢钻针组接触角最小(First=48.67±3.62°,Second=47.52±2.56°),初预备金刚砂钻针组(First=59.77±6.70°,Second=59.32±4.05°)与磨光用金刚砂钻针组接触角(First=62.33±7.01°,Sec-ond=61.33±6.23°)差异无统计学意义(P＞0.05).结论:在本实验的条件下,相比金刚砂钻针,钨钢钻针预备的牙本质表面更光滑、表面润湿性更高、玷污层更均匀、玷污层碎片更少.
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