Aim: The purpose was to compare the fracture strength between restorations containing the metal pin (MP) and those containing the glass fiber pin (GFP).
Materials and methods: Forty-five healthy bovine anterior teeth were used in this study. A preparation of 4 mm × 4 mm was created on the incisal surface of each tooth. All teeth were prepared in the same way. The teeth were randomly divided into three groups (n = 15): group I-control: teeth restored with resin composite (RC) only, without reinforcement; group II-Each tooth was restored with a MP and RC; group III-Each tooth was restored with a GFP and RC. The specimens were left in an oven at a temperature of 37°C for 24 hours before performing the fracture strength tests. The fracture strength test was performed in a universal test machine at an angle of 90°.
Results: The Tukey test (p ≤ 0.05) showed that for the variable maximum force (kgf), there was no statistically significant difference among the groups (p = 0.272). The chi-square test showed that groups II and III presented over 70% of cohesive-adhesive type fractures when compared with group I (over 70% of adhesive fractures), and this difference was statistically significant (p < 0.05).
Conclusion: The pins tested did not increase the fracture resistance of the restorations (RC) in comparison with group I (without reinforcement); however, with the use of the MP and GFP, there was a predominance of cohesive-adhesive fractures (groups II and III).
Clinical significance: Evaluate if the new GFP can generate greater resistance to fracture of RC restorations.
Keywords: Glass fiber pins; Laboratory research Metal pin..