Fracture resistance of teeth restored with 2 different post-and-core designs fixed with 2 different luting cements: an in vitro study. Part II.

Objective: The purpose of this in vitro study was to investigate fracture resistance in teeth restored with cast posts and cores with and without ferrule and using 2 different luting cements. Method and Materials: Forty intact extracted maxillary premolars were endodontically treated after their crowns were removed 2 mm from the cementoenamel junction. Specimens were embedded in acrylic resin blocks, in aluminum cylinders, 2.00 mm apical to the cementoenamel junction. Twenty specimens were ferruled. Within this group, half of the posts and cores were cemented with zinc phosphate cement, while the other half were cemented with resin cement. The same procedures were followed for the nonferruled group. The posts and cores were cast in gold alloy. Specimens were placed in a universal testing machine, and loads were applied at an angle of 45 degrees and a rate of 1 mm/min until the teeth fractured. Analysis of variance and Tukey tests were used for statistical analysis; level of significance was established at 5%. Results: There was no association between type of cement and cervical ferrule; ferruled specimens showed greater resistance than nonferruled ones, regardless of the cement used. Conclusion: A 2-mm cervical ferrule improves fracture resistance of restored teeth, but the type of luting cement used does not seem to affect resistance.