Abstract: 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).

Key words: custom made fiber post, calcium hydroxide, young permanent teeth, fracture resistance