Here the objective was to evaluate fatigue resistance of anterior teeth with flared root canal restored using resin-bonded individualized fiber-reinforced composite (FRC) posts, prefabricated FRC posts, or prefabricated stainless-steel posts. Twenty-four maxillary central incisors were endodontically treated and prepared as flared root canals. They were divided into three groups of 8 each. In Group 1, individual posts were made of FRC material. Prefabricated FRC posts were used for Group 2 and prefabricated stainless-steel posts used in Group 3. All posts were cemented with a self-adhesive resin into canals. The composite core and porcelain fused to metal crown were made for each. The specimens underwent thermocycling and dynamic mechanical loading and survived specimens were loaded to fracture. The data were statistically analyzed using ANOVA and independent sample t-test. In the fatigue test, Group 1 had no failure; all Group 2 specimens failed; and 7 specimens of Group 3 survived. There were significant differences in numbers of cyclically mechanical loading times between Groups 1 and 2, and Groups 2 and 3 (p < 0.01, p < 0.05). The average of residual load-bearing capacity was 317.5 (+/- 90.2) N for Group 1 and 403.8 (+/- 138.2) N for Group 3 and there was no significant difference between these two groups. The fracture mode of specimens was cervical root fracture with or without vertical crack in both Groups 1 and 3. In Group 2 the debonding mostly occurred at the cement-post interface. This in vitro study indicates that the flared canal teeth restored with individually formed FRC posts and prefabricated serrated stainless-steel posts provide good resistance against cyclic loading. The teeth restored with conventional prefabricated FRC posts may not be strong enough to resist masticatory forces without a ferrule. (C) Koninklijke Brill NV, Leiden, 2009