Endodontic sealers and post-endodontic waiting time affect the bond strength of the fiber posts / Cimentos endodônticos e tempo de espera após endodontia afeta a resistência de união de pinos de fibra

Introduction: The resistance adhesive of a fiber post can be affected by several factors, such as the endodontic sealer and post-endodontic waiting time. Objective: The aim of this study was to evaluate the effect of different endodontic sealers and two different post-endodontic waiting times on the bond strength of fiber posts. Material and method: Seventy-two bovine teeth were endodontically treated and filled using three endodontic sealers: eugenol-based, epoxy resin-based, or mineral trioxide aggregate-based. The specimens were stored at 37°C for 24 hours or for 30 months. After the respective storage times, the root canals were prepared for luting fiber posts using RelyX U200. Push-out tests and analysis of failures were performed. The push-out data were analyzed by two-way analysis of variance to compare the effects of the endodontic sealer and with the t-test to compare the effects of post-endodontic waiting time. Result: The AH Plus sealer yielded the highest bond strength values at 30 months post-endodontics (11.26 Mpa) (p < 0.05), however no had difference with Endofill sealer at the same time. Endofill and MTA Fillapex sealers did not differ significantly in their effects, irrespective of the post-endodontic waiting time. Conclusion: In conclusion, the endodontic sealer used and post-endodontic waiting time affect the adhesive resistance of fiber posts. The adhesion increases significantly when the fiber post is cemented 30 months after the root canal filling, while the adhesion is reduced when cementing immediately after root canal treatment, in particular for eugenol-based endodontic sealers.

Introdução: A resistência de união de um pino de fibra pode ser afetada por vários fatores, como o cimento endodôntico e o tempo de espera pós-endodontia. Objetivo: Avaliar o efeito de diferentes cimentos endodônticos e dois tempos de espera pós-endodontia na resistência de união de pinos de fibra. Material e método: Setenta e dois dentes bovinos foram tratados endodonticamente e obturados usando três cimentos endodônticos: à base de eugenol, à base de resina epóxia ou à base de mineral trióxido agregado. Os espécimes foram armazenados a 37 ° C por 24 horas ou por 30 meses. Após, os canais radiculares foram preparados para cimentação dos pinos de fibra usando o RelyX U200. Foram realizados testes de push-out e análise de falhas. Os dados foram analisados por análise de variância bidirecional e com o teste t. Resultado: O cimento AH Plus obteve os maiores valores de resistência de união aos 30 meses pós-endodontia (11,26 Mpa) (p <0,05), no entanto, não houve diferença com o cimento Endofill no mesmo tempo. Os cimentos Endofill e MTA Fillapex não diferiram significativamente em seus efeitos, independentemente do tempo de espera pós-endodontia. Conclusão: O cimento endodôntico utilizado e o tempo de espera pós-endodontia afetam a resistência adesiva dos pinos de fibra. A adesão aumenta significativamente quando o pino de fibra é cimentado 30 meses após a obturação do canal radicular, enquanto a adesão é reduzida ao cimentar imediatamente após o tratamento do canal radicular, principalmente para cimentos endodônticos à base de eugenol.

Endodontic Sealers Affect the Bond Strength of Fiber Posts and the Degree of Conversion of Two Resin Cements.

PURPOSE: To evaluate the effect of two endodontic sealers on the push-out bond strength between fiber posts and root canal wall after different storage times and verify the influence of the endodontic sealers on the degree of conversion of composite cements. MATERIALS AND METHODS: A total of 180 bovine teeth were endodontically treated using two endodontic sealers, eugenol-based (Endofill, Dentsply Maillefer) or epoxy resin-based (AH Plus, Dentsply Maillefer). Subsequently, the specimens were stored in 100% relative humidity at 37°C for 24 h, 6 or 12 months. After the respective storage times, the root canals were prepared for fiber post cementation using two composite cements, RelyX U200 (3M) or Multilink Automix (Ivoclar Vivadent). The push-out test and the failure analysis were performed. Degree of conversion was analyzed using a Raman microscope, for which samples were prepared using composite cement only or composite cement plus endodontic sealer. Finally, the push-out data were subjected to statistical analysis and the degree of conversion in percent was calculated. RESULTS: AH Plus sealer obtained the highest push-out bond strengths at 24 h and 6 months. There was no difference between the push-out bond strengths of AH Plus and Endofill sealer at 1 year (p < 0.05). Moreover, the degree of conversion was affected by the Endofill sealer. CONCLUSION: The use of a eugenol-based sealer is not recommended because it affects the push-out bond strength of fiber posts. AH Plus sealer and a post-endodontic waiting time of 24 h is recommended.

Endodontic Irrigation Protocols: Effects on Bonding of Adhesive Systems to Coronal Enamel and Dentin.

OBJECTIVE:  To evaluate the influence of endodontic irrigation protocols on bond strength of total-etch and self-etch adhesive systems to coronal enamel and dentin. MATERIALS AND METHODS:  A total of 66 coronal slices from 11 permanent molars were assigned to six groups (n = 11): endodontic irrigation protocols (5% sodium hypochlorite + 17% EDTA; 2% chlorhexidine gel + saline solution + 17% EDTA or no solution - control) and adhesive systems (Adper Single Bond 2 or Clearfil SE Bond). Dental slices were exposed to endodontic irrigation protocols for 30-minute prior to the application of the adhesive systems. Starch tubes were placed over the enamel and the dentin surfaces of each slice (2-4 tubes in each substrate) and filled with Filtek Z350 XT (3M ESPE) to build the microshear bond strength (µSBS) specimens (0.72 mm2 sectional area). After 24 hours of water storage (37°C), µSBS test was performed. Bond strength data (MPa) were analyzed by two-way ANOVA, separately for enamel and dentin (α = 0.05). RESULTS:  µSBS means were not influenced by endodontic irrigation protocols in enamel (p = 0.12) nor dentin (p = 0.49). Clearfil SE Bond system presented higher µSBS values than Adper Single Bond 2 both on enamel (p = 0.024) and dentin (p = 0.005). CONCLUSION:  Endodontic irrigation protocols (5% sodium hypochlorite or 2% chlorhexidine gel + saline solution combined with 17% EDTA) do not jeopardize the bond strength of adhesive systems to coronal enamel and dentin. CLINICAL SIGNIFICANCE: The results of this in vitro study suggest that endodontic irrigation protocols do not impair on bonding effectiveness of adhesive systems to coronal enamel and dentin. (J Esthet Restor Dent 29:222-228, 2017).