Cyclic Fatigue of Root Canals Obturated With Different Material Systems

OBJECTIVES: To evaluate the effect of artificially generated occlusal load on the integrity of two commercially available obturation systems. METHODS: 32 maxillary anterior teeth were debrided, decoronated, and reduced to 15mm length. Then, they were cleaned and shaped using Sequence rotary files to 40/06 under 5.25% NaOCl irrigation, and they were obturated with either gutta-percha and AH Plus sealer (Group GP; Dentsply Caulk) or with Resilon and Epiphany sealer (Group Res; Sybron Endo). Teeth from each group (n=12) were allowed to set for 2h and then placed under cyclic force (2Hz, 10-100N load range) at a 45-degree angle to the long axis for 22h while immersed in 37°C water. Cyclic loading was intended to generate two opposing stresses on opposite sides of the canal, one tensile (lingual) and the other compressive (buccal). Other teeth from each group (n=4) were not subjected to cyclic force and served as controls. Each tooth was sectioned with a low-speed saw and finished with 600 grit SiC abrasive disks and then examined using an optical microscope at 520X magnification to assess the integrity of the obturation-root canal interface. The gap width and length of debonded interface were measured and compared statistically using Kruskal-Wallis ANOVA and Dunn's pairwise test (α=0.05) because of unequal variance. RESULTS: Cyclic loaded GP canals showed a significantly longer debonded interface along the tensile surface of the canal while cyclic loaded Res canals showed a significantly longer debonded interface along both the compressive and tensile surfaces of the canals compared to the unloaded GP and Res controls (P≤0.05). CONCLUSION: The results indicate that cyclic loading can cause debonding in canals obturated with both of the material systems investigated.