Influence of ultrasonic activation in association with different final irrigants on intracanal smear layer removal

Aim: To evaluate the influence of ultrasonic activation (US) with different irrigant regimens in smear layer removal. Methods: One hundred bovine incisors were instrumented and divided into ten groups (n=10) according to final irrigation protocols: distilled water (DW); DW+US; 17% EDTA; QMix; 10% citric acid; 37% phosphoric acid; 17% EDTA+US; QMix+US; 10% citric acid+US; 37% phosphoric acid+US. The samples were then submitted to scanning electron microscopy where a score system was used to evaluate the images and effectiveness of proposed treatments. The data were statistically analyzed by Kruskal-Wallis and Mann-Whitney U tests for intergroup comparisons as well as the Wilcoxon and Friedman tests for intragroup comparisons at 5% significance level. Results: In the cervical third, groups 17% EDTA, QMix, 10% citric acid, 17% EDTA+US, QMix+US and 10% citric acid+US were more effective in smear layer removal (p<0.05); in the middle third, groups 17% EDTA+US and QMix+US were more effective in smear layer removal (p<0.05); in the apical third, groups 17% EDTA,17% EDTA+US and QMix+US were more effective in smear layer removal (p<0.05). Conclusions: US can aid 17% EDTA and QMix in smear layer removal at the middle third and QMix at the apical third, contributing to the cleaning of root canal system.

Effect of cleaning methods on bond strength of self-etching adhesive to dentin

Aim:

The aim of this study was to investigate the influence of cleaning methods to remove zinc oxide-eugenol-based root canal sealer (Endomethasone) on the bond strength of the self-etching adhesive to dentin.

Materials and Methods:

Twenty crowns of bovine incisors were cut to expose the pulp chamber. A zinc oxide- and eugenol-based sealer was placed for 10 min in contact with the pulp chamber dentin. Specimens were divided into four groups according to the cleaning method of dentin used: G1, no root canal sealer (control); G2, 0.9% sodium chlorite (NaCl); G3, ethanol; and G4, followed by diamond drill. After cleaning, the teeth were restored with composite resin and Clearfil SE Bond. All specimens were sectioned to produce rectangular sticks and dentin/resin interface was submitted to microtensile bond testing. The mean bond strengths were analyzed using ANOVA/Tukey (α = 0.05).

Results:

G3 and G4 showed bond strengths similar to the G1 (P > 0.05). A significant decrease in the bond strength in the G2 was observed (P < 0.05). G1, G3, and G4, the predominant failure mode was the mixed type. The prevalence of adhesive failure mode was verified in the G2.

Conclusion:

The cleaning methods affected the bond strength of the self-etching adhesive to dentin differently.

Diagnosis of vertical root fracture with cone-beam computerized tomography in endodontically treated teeth: three case reports

A definitive diagnosis of vertical root fracture (VRF) is often a challenging task for clinicians. This is because two dimensional periapical radiographs are usually unable to detect the fracture line due to the direction of the X-ray beam. This report presents a set of 3 cases of endodontically treated teeth that were diagnosed with VRFs based on findings from clinical, radiographic, and cone-beam computerized tomographic (CBCT) examinations. After extraction, VRFs were confirmed in all cases. The presence of periodontal pockets or other signs which would compromise the correct diagnosis could not be detected in all three cases. Fracture lines were only visible with the aid of CBCT which provided useful information for the diagnosis and management of VRF. However, the clinical and radiographic data should not be discarded, but used in conjunction with CBCT.