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OBJECTIVE: This study aimed to evaluate the effect of ultrasonic cleaning of the intracanal post space on the bond strength of fiber posts in oval canals filled with a premixed bioceramic (Bio-C Sealer [BIOC]) root canal sealer. MATERIALS AND METHODS: Fifty premolars were endodontically prepared and divided into 5 groups (n = 10), based on the type of root canal filling material used and the post space cleaning protocol. A1: gutta-percha + AH Plus (AHP) and post space preparation with ultrasonic cleaning, A2: gutta-percha + BIOC and post space preparation with ultrasonic cleaning, B1: gutta-percha + AHP and post space preparation, B2: gutta-percha + BIOC and post space preparation, C: control group. Fiber posts were cemented with a self-adhesive luting material, and 1 mm thick slices were sectioned from the middle and cervical third to evaluate the remaining filling material microscopically. The samples were subjected to a push-out test to analyze the bond strength of the fiber post, and the results were analyzed with the Shapiro-Wilk, Bonferroni, Kruskal-Wallis, and Mann-Whitney tests (p < 0.05). Failure modes were evaluated using optical microscopy. RESULTS: The results showed that the fiber posts cemented in canals sealed with BIOC had lower bond strength than those sealed with AHP. The ultrasonic cleaning of the post space improved the bond strength of fiber posts in canals sealed with AHP, but not with BIOC. CONCLUSIONS: BIOC decreased the bond strength of fiber posts in oval canals, regardless of ultrasonic cleaning.

RESUMO

OBJECTIVES: The objective of this study was to evaluate the bond strength of three root-end filling materials (MTAA-MTA Angelus, MTAS-experimental MTA Sealer, and ZOE- zinc oxide and eugenol cement) in retrograde preparations performed with different ultrasonic tips (CVD, Trinity, and Satelec). MATERIALS AND METHOD: Ninety 2-mm root sections from single-rooted human teeth were used. The retrograde cavities were prepared by using the ultrasonic tips, coupled to a device for position standardization. The specimens were randomly divided into nine groups: CVD MTAA; CVD MTAS; CVD ZOE; Trinity MTAA; Trinity MTAS; Trinity ZOE; Satelec MTAA; Satelec MTAS; Satelec ZOE. Each resin disc/dentin/root-end filling material was placed in the machine to perform the push-out test. The specimens were examined in a stereomicroscope to evaluate the type of failure. Data were submitted to statistical analysis using ANOVA and Tukey tests (α = 0.05). RESULTS: The highest bond strength was observed for the CVD tip irrespective of the material used (P < 0.05). There was no significant difference for the Trinity TU-18 diamond and S12 Satelec tips (P > 0.05). MTAA and MTAS showed highest bond strength. The most common type of failure was adhesion between the filling material and dentin wall, except for ZOE, where mixed failure was predominant. CONCLUSIONS: The CVD tip favored higher bond strength of the root-end filling materials. MTA Angelus and experimental MTAS presented bond strength to dentin prepared with ultrasonic tips. CLINICAL RELEVANCE: Root-end preparation with the CVD tip positively influences the bond strength of root-end filling materials. MTA Angelus and experimental MTAS present bond strength to be used as root-end filling materials.

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AIM: The percentage of Endofill remaining on canal walls after retreatment with different techniques was evaluated using confocal microscopy and qualitative analysis of the interface between the filling material/dentine. METHODOLOGY: Sixty-four root canals of incisors were prepared with ProTaper, filled with gutta-percha and Endofill mixed with 0.1% rhodamine B. The roots were thermocycled and distributed into groups according to the method of evaluation: GI - direct viewing (DV) and GII - operating microscope (OM) and according to the removal technique: A) ProTaper retreatment (PR), B) PR/xylol, C) ultrasound and D) ultrasound/xylol. The root canals were then refilled with gutta-percha and AH Plus with 0.1% fluorescein and sectioned at 2, 4 and 6 mm from the apex. The percentage of remaining Endofill was analysed by confocal microscopy. Additionally, 16 roots were prepared with a ProTaper F5 instrument and were filled with Endofill + 0.1% rhodamine B/gutta-percha (negative control group) (n = 8), and the positive control group (n = 8) were filled with AH Plus with 0.1% fluorescein/gutta-percha. RESULTS: Three-way anova demonstrated differences in the method of evaluation, removal techniques and their interaction (P < 0.05). OM (26.15 ± 12.16%) had a smaller percentage of remaining sealer than DV (32.77 ± 14.47%). The Tukey's test revealed that ultrasound/xylol (15.77 ± 7.15%) led to lower percentages of remaining sealer, significantly different from the PR group (35.25 ± 13.63%), PR/xylol (33.03 ± 11.64%) and ultrasound (33.79 ± 11.71%), which were similar (P > 0.05). Qualitative analysis detected that ultrasound had lower remaining Endofill than PR, particularly when combined with xylol. Operating microscope resulted in lower residual sealer, regardless of the removal technique. CONCLUSIONS: None of the protocols was associated with complete removal of the filling material; however, the use of ultrasound/xylol under an OM provided better results.

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The purpose of this study was to investigate whether the Electrochemical Dissolution (DE) facilitates the retrieval of fractured files, from Endo-Training block with an artificial root canal, by using ultrasonic techniques (US). Twenty Endo-Training block with an artificial single canal with working length 16 mm and twenty nickel-titanium (NiTi) Protaper Universal rotary files were used. 10 Shaping S1 files and 10 Shaping S2 files, were sectioned transversally within the conduit, to 5mm of the apical tip. Twenty samples were divided into four groups: Group1 and 3 received the action of DE and US, and groups 2 and 4 received the action of US. To remove the fragments we used Staging Platform and Dental Microscope. Outcome was analyzed statistically by Student t test. Statistical Analysis showed a significant difference in retrieval time of the fragments and weight loss mass of Endo training block ultrasonic tips were used, between groups that applied Ultrasonic with electrochemical dissolution and the group using only ultrasonic. It can be concluded that there was weight loss mass of separated fragment by electrochemical action, however, it was not sufficient and its use alone was inconclusive to retrieve the fragments. The procedure needs to be complemented with the use of the staging platform, ultrasonic tips and Dental Microscope.

Este estudio tiene como propósito determinar si la Disolución Electroquímica (DE) favorece el retiro de fragmentos de limas fracturadas, insertos en bloc endodónticos de entrenamiento de resina, con un conducto radicular simulado, mediante el uso de ultrasonido (US). Se utilizaron 20 bloc y 20 limas rotatorias usadas ProTaper Universal de NiTi Shaping Files, 10 S1, 10 S2, que fueron fracturadas dentro del conducto, a 5 mm desde la punta apical y divididos en Grupo1 y 3 que recibieron la acción de la DE y US; y Grupo 2 y 4 sólo utilizó US. Para retirar los fragmentos se utilizó Plataforma de Trabajo y Microscopio Dental. Los datos fueron analizados con la prueba T de Student. Los resultados indican que existen diferencias estadísticamente significativas en el tiempo de retiro de los fragmentos y en la pérdida de masa del bloc de entrenamiento por el uso del ultrasonido, en los grupos que se aplicó Disolución Electroquímica más Ultrasonido. Se puede concluir que la acción electroquímica permite que exista pérdida de masa del fragmento fracturado, sin embargo, no es suficiente y su sola utilización no es concluyente para retirar los fragmentos, es necesario complementar el procedimiento con la utilización de la Plataforma de Trabajo, puntas de ultrasonido y el Microscopio Dental.

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