牙本质肩领的应用对不同桩核修复后修复体抗折性能的影响

Effect of ferrule placement on static load failure of teeth restored with different post-core systems

目的:比较不同桩核系统及不同的牙体预备方法对残根抗折强度的影响。方法:40颗下颌前磨牙在釉牙骨质界处截冠后随机均分为四组。A组:金属桩修复的无肩领组。B组:金属桩修复的有肩领组。C组:纤维桩树脂核修复的无肩领组。D组:纤维桩树脂核修复的有肩领组。每组样本都采用金属全冠修复。实验标本包埋于树脂块中,在电子万能测力机上以1mm/min的速度加载直至断裂。结果:A组的抗折裂载荷最高,为3.0369±0.3388KN;D组的抗折强度最低,为2.0188±0.3864KN,A-C、A-B、C-D组间差异有显著性(P<0.05)。可修复性断裂多见于纤维桩树脂核修复组,而不可修复性的破坏多见于铸造桩核组(P<0.05)。结论:当牙体大部分缺损达釉牙骨质界时,通过冠延长术勉强预备牙本质肩领可显著降低桩核修复后牙根的抗折强度。而如不制备牙本质肩领,传统的金属桩核比纤维桩树脂核能承受更大的咀嚼力量。

Objective：To study the effect of different post and cores systems on resistance to fracture ofthe remaining dental tissue of endodontically treated teeth and analyze the relationship of the combined effect of crown lengthening and placement of a ferrule and teeths’ failure resistance.Methods： Forty recently extracted human single rooted lower premolars were cut off from CEJ and randomly divided into group A（Ni-Cr posts and cores without ferrule）,group B（Ni-Cr posts and cores with ferrule）,group C（fiber glass posts and composite resin cores without ferrule） and group D（fiber glass posts and composite resin cores with ferrule）.All teeth were restored with full crown casts.Each specimen was embedded in acrylic resin and secured in a universal material testing machine.A speed of 1mm/min was applied to them until fracture occurred.Results： Group A has the highest fracture resistance with the value of 3.0369±0.3388KN while group D has the lowest fracture resistance with the value of 2.0188 ±0.3864KN.The differences were statistically significant among A and C groups,A and B groups,and C and D groups.（P 0.05）.Repairable fractures more often happened to group C and D;whereas un-repairable fractures were more happened to group A and B（P 0.05）.Conclusion： When teeth are subjected to CEJ level,the combination of crown lengthening and placement of a ferrule can decrease the teeths’ failure resistance.Traditional cast post and core system is more suitable for the teeth without ferrule in this test.