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OBJECTIVES: This study aimed to compare the success and survival rates of metal-ceramic crowns and composite resin restorations applied in root filled teeth that received a glass fiber post. METHODS: A prospective, randomized controlled trial, with equivalent parallel groups was designed. Eighty-two teeth were randomly allocated to the metal-ceramic or composite resin groups. Multivariate Cox regression analysis with shared frailty for patients and Kaplan-Meier curves were performed using success and survival rates (p<0.05). RESULTS: Seventy-five post-retained restorations (34 metal-ceramic crowns and 41 composite restorations) in 62 patients were analyzed. The median follow-up was 8.1 years [IQR 4.0-9.9]. Twenty-seven failures were observed. Twenty-two failures (81.5 %) were observed in the composite resin group, of which six (27.3 %) were not repairable. Five failures (18.5 %) were observed in the metal-ceramic crown group, of which three (66.6 %) were non-repairable. The cumulative success rate at 8 years was 85.0 % for crowns (AFR=1.31 %) and 43.2 % for composite resins (AFR=6.58 %), while the survival rate was 93.8 % for crowns (AFR=0.52 %) and 97.6 % for composite resins (AFR=0.20 %). Considering the success rates, adjusted multivariate Cox regression showed that composite resin had a Hazard Ratio of 5.07 (95 %CI, 1.99-12.89) greater than the metal-ceramic crown. No significant difference in the failure risk was observed when the survival rates were considered (HR=0.38, 95 %CI (0.10 - 1.44), p = 0.156). Co-variables did not affect the success and survival rates (p>0.05). CONCLUSIONS: Metal-ceramic crowns showed a higher success rate than composite restorations. The survival rates were similar, but composite restorations presented a higher need for repairs. CLINICAL SIGNIFICANCE: Post-retained composite restorations may need more reinterventions during the lifecycle, although more preservation of sound tooth structure is expected with a large restoration of resin post-and-core. These aspects have to be discussed with the patient for decision-making planning.

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RESUMO

This study evaluated the effect of air drying temperature and different silane coupling agents on the bond strength between glass fiber posts and composite resin core. The post surface was cleaned with alcohol and treated with different silane coupling agents, being three prehydrolyzed silanes [Silano (Angelus), Prosil (FGM), RelyX Ceramic Primer (3M ESPE)] and one two-component silane [Silane Coupling Agent (Dentsply)]. Two post-silanization air drying temperatures, 23ºC and 60ºC, were applied. A cylindrical plastic matrix was placed around the silanized post and filled with composite resin. Each bonded post provided 7 slices for push-out testing. Each slice was loaded to failure under compression at a cross-head speed of 0.5 mm/min. Data were analyzed by two-way ANOVA and Scott-Knott tests (α=0.05). Dunnett's test was used to compare the mean of the control group with that of each experimental group. Scanning electron microscopy (SEM) was used to evaluate the interface of the fractured slices. For the 23ºC air drying temperature, the use of RelyX Ceramic Primer resulted in significantly lower bond strength than the other silane coupling agents, while the bond strength with Silane Coupling Agent was the highest of all groups. Only with Silane Coupling Agent, the bond strength for the 23ºC air drying temperature was significantly higher than that for 60ºC air drying. In conclusion, the use of warm air drying after silane application produced no increase in the bond strength between the fiber-reinforced composite post and the composite core. The two-component silane produced higher bond strength than all prehydrolyzed silanes when it was used with air drying at room temperature.

Este estudo avaliou o efeito da temperatura do ar e diferentes silanos na resistência de união entre pino de fibra e resina composta. Os pinos foram limpos com álcool e tratados com diferentes silanos: três pré-hidrolizados [Silano (Angelus), Prosil (FGM), RelyX Ceramic Primer (3M ESPE)] e um de dois componentes [Silane Coupling Agent (Dentsply)]. Duas temperaturas (23ºC e 60ºC) para secagem do silano foram aplicadas. Matriz plástica cilíndrica foi posicionada em torno do pino já silanizado, e preenchida com resina composta simulando núcleo de preenchimento. Cada cilindro obtido pela união pino/preenchimento foi seccionado, gerando 7 fatias para ensaio mecânico de push-out. Aplicou-se sobre cada fatia carregamento de compressão, com velocidade de 0,5 mm/min, até a falha da amostra. Os dados foram analisados pela ANOVA e teste Scott-Knott (α=0,05). Utilizou-se teste de Dunnett para comparação do grupo controle com cada um dos outros grupos experimentais. Após ensaio mecânico, observaram-se as amostras em microscópio eletrônico de varredura. Para 23ºC, RelyX Ceramic Primer apresentou os menores valores de resistência de união, enquanto o Silane Coupling Agent (Dentsply) obteve os maiores valores. Para o Silane Coupling Agent (Dentsply), os valores de resistência de união foram maiores para temperatura de 23ºC do que 60ºC. Em conclusão, o uso de ar quente após aplicação do silano não gerou aumento nos valores de resistência de união entre pino de fibra e material de preenchimento de resina composta. O silano de dois componentes apresentou maior resistência de união do que todos os silanos pré-hidrolizados quando usados na temperatura ambiente.

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