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目的 观察粘接纤维桩核后不同间隔时间核预备对桩核系统微渗漏的影响,以期为临床桩核预备时机提供实验依据.方法 对45颗人下颌前磨牙进行截冠、根管预备和热牙胶充填,并分别于纤维桩核粘接后5、15和30 min行核预备(桩核组,每组10颗样本牙),阳性对照组(每组5颗样本牙)仅充填根尖5 mm热牙胶,阴性对照组(每组10颗样本牙)桩核修复后不进行核预备.采用液体输送法检测桩核系统微渗漏量,并于扫描电镜下观察并测量粘接界面缝隙.结果 高速机头行核预备后桩核系统微渗漏量增加,阴性对照组微渗漏量[(1.50×10-6 ±0.37×10-6) μl· min-1·Pa-1]均显著低于3个桩核组(P＜0.05)；5 min桩核组微渗漏量为(6.02 ×10-5 ±1.02 ×10-5)μ1·min-1·pa-1,明显高于15 min桩核组[(1.50×10-5 ±0.26×10-5) μl· min-1·Pa-1 ]和30 min桩核组[ (1.50 ×10-5±0.39×10-5)μl· min-1·Pa-1] (P＜0.05).扫描电镜观察5 min桩核组根管壁与粘接剂间缝隙较大,且由根尖向根颈逐渐扩大.结论 高速机头振动对纤维桩核系统封闭性有负面影响,本项实验条件下粘接纤维桩核后应过15 min再行核预备,微渗漏量显著降低.

Objective To evaluate the microleakage of fiber post and core systems after high-speed handpiece preparation at different time points.Methods The crowns of forty-five extracted human premolar were removed and the roots were endodontically treated.The samples were devided into five groups.Root canal preparation was performed on each premolar followed by fiber post cementation and core build up.Tooth preparation was applied at 5 min in group 1,at 15 min in group 2 and at 30 min in group 3 after post cementation.Five teeth with only 5 mm apical sealing were served as a positive control group,and ten with fiber post and core build-up but no coronal preparation were taken as a negative control group.Microleakage was evaluated using a fluid filtration system.The bonding interface was observed by scanning electronic microscope(SEM).Results The microleakage was significantly increased after coronal preparation with high-speed handpiece.The negative control group has less leakage [ ( 1.50 × 10 -6 ± 0.37 × 10 -6 ) μ1 ·min-1 · Pa- 1 ] than the groups with coronal preparation ( P ＜ 0.05 ) ; Group 1 leaked significantly more [(6.02 ×10-5 ±1.02 × 10-5) μ1 · min-1 · Pa-1] than group 2[(1.50 × 10-5 ±0.26 × 10-5) μl ·main-1 ·Pa-1] and group 3[(1.50 × 10-5 ±0.39 × 10-5)μl · min-1 · Pa-1] did (P ＜0.05).Corresponding to microleakage,the micro gaps between the resin cement and dentine in group 1 were wider than those in the other groups.The coronal section was wider than the apical part.Conclusions Highspeed handpiece had negative effects on microleakage of fiber post and core systems.Coronal preparation should be performed 15 min or more after post cementation.