Resumo Objetivo Este trabalho avaliou a carga para fratura e deslocamento de raízes restauradas com pinos de diferentes módulos de elasticidade. Material e método Trinta e seis réplicas de microfibras de vidro embutidas em resina epóxi foram fabricadas a partir de uma raiz de um pré-molar tratado endodonticamente preparado em 12 mm de comprimento com brocas customizadas, deixando 4 mm apicais sem preparo. As raízes foram randomicamente restauradas com (n = 12): FP-LM (pino de fibra com um baixo módulo de elasticidade – 50 GPa), FP-HM (pino de fibra com um alto módulo de elasticidade – 67 GPa) e MP (pinos metálicos – 208 GPa), usando adesivo autopolimerizável e cimento resinoso dual. Núcleos foram confeccionados com resina composta e coroas metálicas foram cimentadas em todas as raízes com cimento resinoso autoadesivo com modo de polimerização químico. Os espécimes foram submetidos ao teste de fratura em 45° (inclinação de 45° / 0,5 mm/min) e o deslocamento foi registrado aos 100 N. Resultado Anova 1 fator mostrou que o módulo de elasticidade dos retentores não afetou as médias de fratura (p = 0,203) (FP-LM: 237,4 ± 65,11 N; FP-HM: 236,7 ± 92,85 N; MP: 295,8 ± 108,7 N) mas foi estatisticamente significante para o deslocamento (p < 0,00): o teste de Tukey mostrou que a média de deslocamento do grupo FP-LM (0,81 ± 0,15 mm) foi significativamente maior do que o grupo FP-HM (0,46 ± 0,26 mm; p = 0,00) e MP (0,62 ± 0,07 mm; p = 0,47). Conclusão Pinos com diferentes módulos de elasticidade mostram resistência similar, porém um menor deslocamento é obtido quando pinos de fibra com alto módulo de elasticidade (FP-HM/MP) são usados.

Abstract Objective This study aimed to evaluate the fracture load and displacement of roots restored with posts of different elastic modulus. Material and method Thirty-six replicas of epoxy resin mixed with glass microfibers were made from an endodontically-treated human premolar root prepared to a length of 12 mm with a custom drill, leaving the apical 4 mm unprepared. Replicas were randomly restored with (n = 12): FP-LM (fiber post with low elastic modulus– 50 GPa), FP-HM (fiber post with high elastic modulus – 67 GPa) and MP (metallic post – 208 GPa), using self-curing adhesive and dual resin cement. Cores were built up with composite resin and metallic crowns were cemented in all the roots with self-adhesive resin cement with self-curing mode. Specimens were subjected to a fracture load test (45° inclination/0.5 mm/min) and displacement was registered at 100 N. Result One-way ANOVA showed that elastic modulus of the post did not affect the fracture load means (p = 0.203) (FP-LM: 237.4 ± 65.11 N; FP-HM: 236.7 ± 92.85 N; MP: 295.8 ± 108.7 N) but was statistically significant for the displacement (p < 0.00): Tukey’s test showed that FP-LM displacement mean (0.81 ± 0.15 mm) was significantly higher than those for FP-HM (0.46 ± 0.26 mm; p = 0.00) and MP (0.62 ± 0.07 mm; p = 0.04). Conclusion Posts with different elastic modulus exhibit similar fracture loads, but a lower displacement is achieved when fiber posts with a high elastic modulus and metallic posts are used.

Abstract The aim of this systematic review was to compare the clinical performance and failure modes of teeth restored with intra-radicular retainers. A search was performed on PubMed/Medline, Central and ClinicalTrials databases for randomized clinical trials comparing clinical behavior and failures of at least two types of retainers. From 341 detected papers, 16 were selected for full-text analysis, of which 9 met the eligibility criteria. A manual search added 2 more studies, totalizing 11 studies that were included in this review. Evaluated retainers were fiber (prefabricated and customized) and metal (prefabricated and cast) posts, and follow-up ranged from 6 months to 10 years. Most studies showed good clinical behavior for evaluated intra-radicular retainers. Reported survival rates varied from 71 to 100% for fiber posts and 50 to 97.1% for metal posts. Studies found no difference in the survival among different metal posts and most studies found no difference between fiber and metal posts. Two studies also showed that remaining dentine height, number of walls and ferrule increased the longevity of the restored teeth. Failures of fiber posts were mainly due to post loss of retention, while metal post failures were mostly related to root fracture, post fracture and crown and/or post loss of retention. In conclusion, metal and fiber posts present similar clinical behavior at short to medium term follow-up. Remaining dental structure and ferrule increase the survival of restored pulpless teeth. Studies with longer follow-up are needed.

Objective: Considering that periodontal ligament simulation may influence the stress distribution over teeth restored with intraradicular retainers, this study aimed to assess the combined effect of mechanical cycling and periodontal ligament simulation on both the bond strength between fiber posts and root dentin and the fracture resistance of teeth restored using glass fiber posts. Material and Methods: Ninety roots were randomly distributed into 3 groups (n=10) (C-MC: control; P-MC: polyether; AS-MC: addition silicone) to test bond strength and 6 groups (n=10) (C: control; P: polyether; AS: addition silicone, without mechanical cycling, and C-MC, P-MC and AS-MC with mechanical cycling) to test fracture strength, according to the material used to simulate the periodontal ligament. For the bond strength test, fiber posts were cemented, cores were built, mechanical cycling was applied (2×106 cycles, 88 N, 2.2 Hz, and 45º incline), and the teeth cut into 3 slices (2 mm), which were then subjected to the push-out test at 1 mm/min. For the fracture strength test, fiber posts were cemented, cores were built, and half of the groups received mechanical cycling, followed by the compressive strength (45° to the long axis and 1 mm/min) performed on all groups. Results: Periodontal ligament simulation did not affect the bond strength (p=0.244) between post and dentin. Simulation of periodontal ligament (p=0.153) and application of mechanical cycling (p=0.97) did not affect fracture resistance. Conclusions: The materials used to simulate the periodontal ligament did not affect fracture or bond strength, therefore periodontal ligament simulation using the tested materials could be considered optional in the conditions of the study.