[Effect of fiber posts on the fracture resistance of immature permanent teeth]

To investigate the influence of different cements on the fracture resistance of the immature teeth restored with fiber post and the fracture resistance at different parts of the roots.

Seventy-five untreated maxillary and mandibular premolar were selected for this study, and randomly assigned to 5 groups, including 2 experimental groups, 2 positive controls, and 1 negative control. After root canal therapy was applied for each tooth, the post space was prepared to standard size and restored according to the proposal. The samples were embedded, and the fracture resistance at cervical 1/3 and middle 1/3 of the root was measured. The data was analyzed with SAS6.0 software package.

The average fracture resistance at cervical, middle 1/3 was (999+/-75.40)N,(799+/-21.77)N in samples restored with 1.9mm fiber post+composite resin cement, (896+/-15.73)N, (739+/-20.14)N in samples restored with 1.9mm fiber post+glass ionomer cement, the difference was significant(P<0.01).

The cements play some role on the fracture resistance at cervical 1/3 and middle 1/3 of the root of immature teeth restored with fiber post. The immature teeth are at high risk of root fracture because of its thin dentin, therefore we propose to use composite resin cement as a bonding material when immature teeth are restored with fiber posts. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2271100).