IADR Abstract Archives
Effect of load cycling on the fracture strength/mode of root canal treated teeth restored with FRC-posts or FRC-base
Objectives: To comparatively evaluate the fracture strength and failure mode pattern of root canal treated teeth restored FRC-posts or FRC-base plus a particle-filled composite.
Methods: Intact first upper premolars with two roots, extracted for orthodontic reasons, were distributed into 2 groups (A,B, 2x10 teeth each), with similar premolar sizes in each group. The lingual cusps of all teeth were removed down to cervical enamel. The teeth were subjected to root-canal treatment, provisionally sealed and following 1w-storage (H2O/37oC) were restored as follows: Group A: 1) FRC-post luted into lingual canal; 2) enamel acid etching; 3) adhesive treatment (G-Aenial Bond,10s-exp); 3) particle-filled composite application (G-Aenial, 3x2mm increments, 40s-exp each), 4) contouring-finishing-polishing. Group B: 1) Removal of gutta-percha down to 2mm depth from cut cervical enamel; 2) etching and adhesive treatments as above 3) application of a FR composite base (Ever-X, 4mm layer); 4) application of the particle-filled composite (2mm layer); 5) contouring-finishing-polishing. Specimens were immersed in H2O (1w/37oC), then subjected to load-cycling (50N/2Hz/200k cycles) and fractured under compressive loading. Failure mode was characterized by stereomicroscopy. Statistical analysis was performed by Mann-Whitney (load) and x2 (mode) at a=0.05.
Results: No statistically significant differences (p=0.273) were found in fracture load between median values of groups A (860 N) and B (1059 N). In group A, 60% of the specimens demonstrated catastrophic root fractures and 40% mixed fractures (residual tooth crown and restorative material), whereas in group B, no root fractures were found and the failure modes were equally distributed between mixed fractures as above and fracture of the buccal cusp. The differences in mode between groups A and B were statistically significant (p=0.004).
Conclusions: The FR-base composite tested significantly modified failure mode, diminishing the catastrophic root fractures induced by FRC-posts, at a similar fracture load.
Methods: Intact first upper premolars with two roots, extracted for orthodontic reasons, were distributed into 2 groups (A,B, 2x10 teeth each), with similar premolar sizes in each group. The lingual cusps of all teeth were removed down to cervical enamel. The teeth were subjected to root-canal treatment, provisionally sealed and following 1w-storage (H2O/37oC) were restored as follows: Group A: 1) FRC-post luted into lingual canal; 2) enamel acid etching; 3) adhesive treatment (G-Aenial Bond,10s-exp); 3) particle-filled composite application (G-Aenial, 3x2mm increments, 40s-exp each), 4) contouring-finishing-polishing. Group B: 1) Removal of gutta-percha down to 2mm depth from cut cervical enamel; 2) etching and adhesive treatments as above 3) application of a FR composite base (Ever-X, 4mm layer); 4) application of the particle-filled composite (2mm layer); 5) contouring-finishing-polishing. Specimens were immersed in H2O (1w/37oC), then subjected to load-cycling (50N/2Hz/200k cycles) and fractured under compressive loading. Failure mode was characterized by stereomicroscopy. Statistical analysis was performed by Mann-Whitney (load) and x2 (mode) at a=0.05.
Results: No statistically significant differences (p=0.273) were found in fracture load between median values of groups A (860 N) and B (1059 N). In group A, 60% of the specimens demonstrated catastrophic root fractures and 40% mixed fractures (residual tooth crown and restorative material), whereas in group B, no root fractures were found and the failure modes were equally distributed between mixed fractures as above and fracture of the buccal cusp. The differences in mode between groups A and B were statistically significant (p=0.004).
Conclusions: The FR-base composite tested significantly modified failure mode, diminishing the catastrophic root fractures induced by FRC-posts, at a similar fracture load.