目的 · 观察可塑纤维桩对氢氧化钙作用不同时间后年轻恒牙抗折性能的影响。方法 · 选取离体年轻恒前磨牙 45 颗，随机分为 9 组。1 组为空白对照组； 8 组经根管预备，其中 4 组（FⅠ、FⅢ、FⅥ、FⅨ）分别在氢氧化钙水糊剂作用 1、3、6、9 个月后行根管充填 并置入可塑纤维桩修复，4 组（CⅠ、CⅢ、CⅥ、CⅨ）不置入可塑纤维桩。所有样本进行断裂载荷测定并分析其折裂模式是否具有二次 修复性。结果 · 氢氧化钙作用 1 个月后，断裂载荷值随着氢氧化钙作用时长的增加而逐渐降低（P<0.01）；氢氧化钙作用 6 个月及 9 个月后，置入可塑纤维桩组断裂载荷值均有所增高（P<0.05，P<0.01）。氢氧化钙作用 1 个月后，与未置入可塑纤维桩组相比，置入 可塑纤维桩组更易出现利于二次修复的折裂模式（P<0.05）。 结论 · 当氢氧化钙需中长期（≥ 1 个月）作用于年轻恒牙时，置入可塑 纤维桩可提高牙根的抗折性能。

Objective · To observe the effects of custom made fiber posts on the fracture resistance of young permanent teeth treated with calcium hydroxide for different time.  Methods · Forty-five extracted human young permanent teeth (premolar) were selected and randomly assigned to 9 groups. One group was the control group and the rest 8 groups were treated with conventional root canal preparation. Of these 8 groups, 4 groups (FⅠ, FⅢ, FⅥ, FⅨ) were restored by custom made fiber posts after being treated with calcium hydroxide for 1, 3, 6, and 9 months respectively, and other 4 groups (CⅠ, CⅢ, CⅥ, CⅨ) were not restored by custom made fiber posts. All samples underwent fracture strength tests and their fracture modes were analyzed for the possibility of second repair.  Results · The fracture load was decreased with the treatment time after being treated with calcium hydroxide for 1 month (P<0.01). The fracture loads in groups restored by custom made fiber posts were increased after being treated with calcium hydroxide for 6 and 9 months (P<0.05, P<0.01). After being treated with calcium hydroxide for 1 month, groups restored by custom made fiber posts were likely to have fracture modes that facilitate the second repair as compared with groups not restored by custom made fiber posts (P<0.05).  Conclusion · The restoration by custom made fiber posts can increase the fracture resistance of young permanent teeth treated with calcium hydroxide for medium and long term ( ≥ 1 month).