The effect of glass fiber posts and ribbons on the fracture strength of teeth with flared root canals restored using composite resin post and cores.

PURPOSE: This study evaluated the fracture strength and mode of failure of structurally compromised teeth with flared root canals restored using composite resin with four different systems.

METHODS: Sixty endodontically treated bovine teeth were uniformly shaped to simulate human mandibular premolars with flared root canals. The roots were divided into four groups of 15 specimens each based on the type of restoration: composite resin core only (control), glass fiber post, cylindroid glass fiber ribbons, and glass fiber post and ribbons. All specimens were loaded until fracture occurred using a universal testing machine. Average fracture loads were compared with a one-way ANOVA and Tukey HSD test (α=.05). The modes of failure were observed and the Fisher exact test and Bonferroni correction were used for statistical analysis.

RESULTS: The fiber post and ribbon group (1035.70N) and the fiber ribbon group (881.77N) showed significantly higher fracture strength than the controls (567.97N) (p<.05). The fiber post and ribbon group also showed significantly higher fracture strength than the fiber post group (769.40N). Almost all specimens showed unrestorable root fractures (p<.008). The control group had a significantly higher ratio of core sectional fractures (p<.017).

CONCLUSIONS: Cylindroid glass fiber ribbons significantly increased the fracture strength of the composite resin post and cores in the case of the dentin within the thin root canal wall. Based on the results, this study recommends the combined use of glass fiber post and ribbons.