Resin cement and glass fibre accessories posts: photoelastic analysis

Objective: This study assessed the stress generated by resin cement on the walls of the prepared root with or without insertion of principal and/or accessory pre-fabricated glass fibre posts through photoelastic technique. Methods: The specimens were made of photoelastic resin discs with an inner orifice (2 mmƒÖ and 4 mm height). The specimens were sandblasted with aluminum oxide and coated with an adhesive layer (Scotchbond Multi-purpose), and photoactivated by 20s. The specimens were divided into 5 groups (n=5) according to section of post used: Group 1 (G1) (control) - cement resin BiFix, Group 2 (G2) -one principal glass fibre post (Reforpost), Group 3 (G3) - 1 principal and 2 accessory glass fibre posts (Reforpin) Group 4 (G4) -5 accessories posts. After polymerization the specimens were analysed and the visual representation of stress were measured through the program Imagetool using the isocromatic ring of order 1. The data were converted into MPa through a proper equation and the data submitted to ANOVA and Tukey's test (5%). Results: G1 (3.48 °" 0.23) did not differ from G2 (3.27 °" 0.26), but both differ from G3 (2.82 °" 0.14) and G4 (2.80 °" 0.18), which did not differ among each other. Conclusion: The inclusion of accessories posts can contribute to reducing the contraction stress on the walls of the root canals.