The aim of this study was to evaluate the fracture resistance of endodontically maxillary premolars restored with mesio-occlusal-distal (MOD) inlays made with ceramic (IPS-Empress 2) and ceromer (Targis) and luted with three different dual-cured resin cements (Enforce, Variolink II, Panavia F). Sixty maxillary premolars were randomly distributed into six groups, according to their mesio-distal and facio-lingual dimensions. The teeth were endodontically treated and MOD cavities prepared. After the restorations were cemented, the samples were thermocycled and submitted to an axial compressive load by the action of a rounded end steel cylinder contacting the incline planes of occlusal surfaces of the teeth. The mode of fracture was analysed with a microscope. The best results were found with the combinations (cement/restorative material) Enforce/Targis (107.57 kgf) and Enforce/Empress (90.21 kgf) followed by Variolink II/Targis (86.44 kgf)-Variolink II/Empress (84.07 kgf) and Panavia F/Targis (82.43 kgf)-Panavia F/Empress (76.73 kgf). Analysis of variance (P < 0.05) showed a significant difference between Enforce and Panavia cements regardless of the restorative material. Considering the same luting agent there was no statistically significant difference between the restorative materials. Fracture of lingual cusps occurred in 55 of the 60 teeth and most of them were of the cohesive type.
The dental prosthesis market is rapidly evolving to meet patient and clinical demands. These new materials must have good flexural strength, toughness, aesthetic properties, and reliability in performance for structural applications. The present work aimed to compare the bending strength of 4 types of chairside lithium disilicate (Li2Si2O5) glass-ceramics used for dental prosthesis and to analyze the influence of heat treatment on the transformation of lithium metasilicate (Li2SiO3) into lithium disilicate. The three-ball test for the biaxial flexion test (B3B) was used. Weibull statistical analysis was used, and it showed that samples with a higher percentage of zirconia have a greater tendency to fail. The flexion tests showed that the addition of more than 10% of zirconia reduced the flexural strength. The heat treatment process improves and provides greater mechanical strength. The XRD results indicated that the samples with the lowest percentage of zirconia exhibited greater crystallinity and corroborated the microstructural analysis. SEM analyses showed a greater amount and elongated crystals of lithium disilicate when comparing samples with a higher percentage of zirconia. Therefore, samples with lower zirconia showed greater flexural strength than samples with higher additions of zirconia.
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Objective: The aim of the present study was to compare the fracture strength of endodontically restored teeth with glass-fiber pin and experimental pin of computer-aided design / computer-aided manufacturing (CAD / CAM). Methodology: A total of 20 bovine incisors with sectioned crowns and roots were prepared with 15mm length were randomly divided into two groups (n = 10): G1 - pin fiber glass (control) and G2 - pin machined (experimental). In both groups, the samples had their root canals treated endodontically. The roots were included in acrylic resin, the pins cemented with dual resin cement and subsequently subjected to the compression fracture strength test at a speed of 0.05 mm / min under a 45 ° angle in a universal test machine until the fracture. The values of fracture resistance were submitted to Student's t-test with the SPSS program with a significance level of 5%. Results: According to the tests, the results required strength at fracture was lower in the pre-fabricated custom (48.2kgf) fiber pin group than the group of pins milled by the CAD / CAM system (56.9kgf), however no there was a statistical difference between them (p = 0.26). With a mean SD ± 14.6 for the first and ± 19.0 for the second group. Conclusion: Fiber pins developed by CAD / CAM technology may appear as a viable alternative for intraradicular restorations of endodontically treated elements, since there was no statistical difference in fracture resistance with pre-fabricated pins.
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