Shamseddine Loubna, Eid Rita, Homsy Fodda, Elhusseini Hasan
Department of Prosthodontics, School of Dentistry, Lebanese University, Beirut, Lebanon.
Endodontist, Private Practice, Beirut, Lebanon.
J Dent Biomech. 2014 Aug 12;5:1758736014547550. doi: 10.1177/1758736014547550. eCollection 2014.
When fabricating indirect post and core, internal coronal walls are tapered to remove undercuts and allow a better adaptation. To evaluate the fracture strength of anterior tooth reconstructed with post and core and crowned, with two different taper of internal coronal walls, 6° and 30° to the long axis, two groups of 30 clear plastic analogues simulating endodontically treated maxillary central incisors were prepared. The analogues crowned were subjected to a compressive load with a 1-kN cell at a crosshead speed of 0.05 mm/min at 130° to the long axis until fracture occurred. Data were analyzed by Lillifors and Mann-Whitney tests. Mean failure loads for the groups were as follows: group I 1038.69 N (standard deviation ±243.52 N) and group II 1231.86 N (standard deviation ±368.76 N). Statistical tests showed significant difference between groups (p = 0.0010 < 0.01). Increasing the taper of internal coronal walls appears to enhance the fracture resistance of anterior maxillary teeth post and core reconstructed.
制作间接桩核时，牙冠内部壁制成锥形以消除倒凹并实现更好的贴合。为评估用桩核修复并戴冠的前牙在牙冠内部壁与长轴呈6°和30°两种不同锥度时的抗折强度，制备了两组各30个模拟根管治疗后的上颌中切牙的透明塑料模型。给戴冠的模型在与长轴呈130°的方向上以0.05 mm/min的十字头速度通过1kN的压力传感器施加压缩载荷，直至发生断裂。数据采用Lillifors检验和Mann-Whitney检验进行分析。两组的平均破坏载荷如下：第一组1038.69 N（标准差±243.52 N），第二组1231.86 N（标准差±368.76 N）。统计检验显示两组之间存在显著差异（p = 0.0010 < 0.01）。增加牙冠内部壁的锥度似乎可增强上颌前牙桩核修复体的抗折性。
