Mechanical properties of composite core material with fiber posts

Objective: To evaluate the influence of different types of posts on the diametral tensile strength (DTS) and fracture Toughness (FT) of a resin composite core material. Methods: For DTS test, disc specimens, 6 mm in diameter and 3 mm thick, were prepared from resin composite (ParaCore) and a group of pre-fabricated glass fiber posts (n=15) as follows: resin composite only (control Group1); EverStick (Group2); ParaPost (Group3). Specimens were soaked at 37 °C for 7 days in deionized water and then subjected to DTS test using an Instron universal testing machine until failure occurred and maximum load was recorded (N). Mean values and SD for DTS values (MPa) were calculated, and data were analyzed statistically using one-way analysis of variance, followed by the Tukey B rank order test (p=.05). For FT test, triangular prism specimens (6mmX6mmX12mm) were prepared from ParaCore build-up material (n=15) as follows: ParaCore only (Group4), ParaCore and EverStick (Group5), and ParaCore and ParaPost (Group6). Specimens were stored in deionizedwater then tested, and data analyzed as for the DTS groups. Results: Mean values (SD) in MPa for DTS were as follow: ParaCore: 41.07(2.66); EverStick: 29.89(4.19); ParaPost: 28.35(2.15). Analysis of variance indicated significant differences among the groups except between groups 2 and 3. (P=05). FT mean values (SD) were: ParaCore: 1.70 (0.53); ParaCore and EverStick: 1.56 (0.38); ParaCore and ParaPost: 1.55 (0.34). No statistical significance among the FT groups were found using at p=0.05. Conclusion: The use fiber posts reduced the strength of the core material under DTS. FT test produced inconclusive results.

Acknowledgments: Coltene/Whaledent