Ricardo Abreu da Rosa

Effect of Passive Ultrassonic Instrumentation as a Final Irrigation Protocol on Debris and Smear Layer Removal—A SEM Analysis

This study sought to evaluate the efficacy of passive ultrasonic irrigation (PUI) on removing the smear layer and debris from root dentin using scanning electron microscopy (SEM). Twenty‐five bovine incisors were manually prepared and divided into three groups according to the final irrigation protocol: EDTA, final irrigation with 12 mL of 17% EDTA for 3 minutes followed by 5 mL of 2.5% NaOCl; EDTA/PUI, final flush with 4 mL of 17% EDTA and PUI for 30 seconds. These procedures were repeated three times to standardize the volume of the irrigant. Control group, after preparation, the specimens were irrigated only with 17 mL of 2.5% NaOCl. The roots were fractured and analyzed using SEM. The intragroup analysis revealed that the EDTA/PUI protocol removed a higher amount of debris at the cervical third (P = 0.03). The intergroup analysis revealed that EDTA/PUI presented the lowest amount of debris at the cervical third (P = 0.007). Smear layer scores were higher in the control group compared with the EDTA and EDTA/PUI groups, but only at the cervical third (P = 0.02). None of the final irrigant protocols completely removed the smear layer and debris. EDTA/PUI only improved the removal of debris at the cervical third. Microsc. Res. Tech. 76:496–502, 2013.

Influence of Endodontic Sealer Composition and Time of Fiber Post Cementation on Sealer Adhesiveness to Bovine Root Dentin

This study aimed to assess the influence of the type of endodontic sealer (salicylate resin-based sealer vs. two endodontic sealers) and the time of fiber post cementation after root filling on the post adhesion to bovine root dentin. Sixty bovine roots were assigned to six groups (n=10), considering an experimental design with two factors (factorial 3x2): endodontic sealer factor in three levels [epoxy resin-based sealer (AH Plus), eugenol-based sealer (Endofill), and salicylate resin-based sealer plus mineral trioxide aggregate - MTA (MTA Fillapex)] and time for post cementation factor in two levels (immediate post cementation or 15 days after root canal filling). After post cementation, 2-mm-thick slices were produced and submitted to push-out test. The failure modes were analyzed under a 40× stereomicroscope and scored as: adhesive at cement/dentin interface; adhesive at cement/post interface; cement cohesive; post cohesive; dentin cohesive; or mixed. Data were analyzed using two-way ANOVA and Tukeys post-hoc tests (α=0.05). When the fiber posts were cemented immediately after the root canal filling, the bond strengths were similar, independent of the endodontic sealer type. However, after 15 days, the epoxy resin-based sealer presented higher bond strength than the other sealers (p<0.05). Comparison between each sealer in different experimental times did not reveal any differences. The main failure type was adhesive at dentin/cement interface (89.4%). The time elapsed between the root canal filling and post cementation has no influence on post/root dentin adhesion. On the contrary, the type of endodontic sealer can influence the adhesion between fiber posts and root dentin.

The influence of different cements on the pull-out bond strength of fiber posts

STATEMENT OF PROBLEM Glass fiber posts are commonly used to provide adequate support and retention for the restoration of endodontically treated teeth, but their resistance to dislodgement depends on their adhesion to root dentin. PURPOSE The purpose of this study was to assess the effect of cement type on the pull-out bond strength of fiber posts. MATERIAL AND METHODS Seventy maxillary canines were endodontically treated and then divided into 7 groups according to the cement used for fiber post cementation as follows (n = 10): RelyX Unicem, BisCem, RelyX Luting 2, RelyX ARC, Panavia F, Enforce, and Allcem. The specimens were subjected to a pull-out bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The results, in newtons, were analyzed with 1-way ANOVA and the Tukey post hoc test (α = .05). RESULTS RelyX Unicem (472.3 ± 8.9 N), BisCem (506.6 ± 9.2 N), RelyX ARC (498.0 ± 8.2 N), Panavia F (502.3 ± 7.0 N), and Allcem (470.0 ± 11.3 N) presented significantly higher bond strength than RelyX Luting 2 (241.8 ± 9.70 N) and Enforce (309.5 ± 6.3 N) cements (mean ± SD; P < .05). CONCLUSIONS Except for Enforce, all resin cements produced pull-out bond strength values twice that of resin modified glass ionomer cement. However, all cements promoted adequate retention to fiber posts to withstand functional loads.

Effectiveness of Final Irrigant Protocols for Debris Removal from Simulated Canal Irregularities

INTRODUCTION The aim of this in vitro study was to compare the effectiveness of saline, 2.5% sodium hypochlorite, and 2% chlorhexidine, with or without passive ultrasonic irrigation (PUI), in debris removal from simulated canal irregularities within prepared root canals. METHODS Ninety bovine lateral incisors were randomly divided into 3 main groups (n = 30) based on the irrigant and prepared with hand files attached to an oscillating handpiece (NSK, Tokyo, Japan) up to a size #80 K-file. Next, the teeth were split longitudinally, and a standardized groove was prepared into the apical third and filled with dentin debris. After the halves were reassembled, they were placed in a muffle. Each main group was randomly subdivided into 2 groups (n = 14) and was treated with different final irrigation protocols. In the sodium hypochlorite/PUI, chlorhexidine/PUI, and saline/PUI groups, the solution was ultrasonically activated 3 times for 20 seconds. In the remaining groups, PUI was not performed. Specimens were scored for debris removal and analyzed under a scanning electron microscope. RESULTS An association was observed between the score of debris removal and protocols using PUI (P < .05). No association was observed between the scores of debris removal and the irrigants (P = .87). CONCLUSIONS Final irrigation protocols that used PUI were more effective in removing debris from simulated canal irregularities into the apical third than those that did not use it.

Wizard CD Plus and ProTaper Universal: analysis of apical transportation using new software

Objective This study has two aims: 1) to evaluate the apical transportation of the Wizard CD Plus and ProTaper Universal after preparation of simulated root canals; 2) to compare, with Adobe Photoshop, the ability of a new software (Regeemy) in superposing and subtracting images. Material and Methods Twenty five simulated root canals in acrylic-resin blocks (with 20º curvature) underwent cone beam computed tomography before and after preparation with the rotary systems (70 kVp, 4 mA, 10 s and with the 8×8 cm FoV selection). Canals were prepared up to F2 (ProTaper) and 24.04 (Wizard CD Plus) instruments and the working length was established to 15 mm. The tomographic images were imported into iCAT Vision software and CorelDraw for standardization. The superposition of pre- and post-instrumentation images from both systems was performed using Regeemy and Adobe Photoshop. The apical transportation was measured in millimetres using Image J. Five acrylic resin blocks were used to validate the superposition achieved by the software. Students t-test for independent samples was used to evaluate the apical transportation achieved by the rotary systems using each software individually. Students t-test for paired samples was used to compare the ability of each software in superposing and subtracting images from one rotary system per time. Results The values obtained with Regeemy and Adobe Photoshop were similar to rotary systems (P>0.05). ProTaper Universal and Wizard CD Plus promoted similar apical transportation regardless of the software used for images superposition and subtraction (P>0.05). Conclusion Wizard CD Plus and ProTaper Universal promoted little apical transportation. Regeemy consists in a feasible software to superpose and subtract images and appears to be an alternative to Adobe Photoshop.

An in vivo radiographic evaluation of the accuracy of Apex and iPex electronic Apex locators

The aim of this study was to evaluate in vivo the clinical applicability of two electronic apex locators (EALs) - Apex (Septodont) and iPex (NSK) - in different groups of human teeth by using radiography. The working lengths (WLs) of 100 root canals were determined electronically. The EAL to be used first was chosen randomly and a K-file was inserted into the root canal until the EAL display indicated the location of the apical constriction (0 mm). The K-file was fixed to the tooth and a periapical radiograph was taken using a radiographic film holder. The K-file was removed and the WL was measured. The same procedure was repeated using the other EAL. Radiographs were examined with the aid of a light-box with lens of ×4 magnification by two blinded experienced endodontists. The distance between the file tip and the root apex was recorded as follows: (A) +1 to 0 mm, (B) -0.1 to 0.5 mm, (C) -0.6 to 1 mm, (D) -1.1 to 1.5 mm, and (E) -1.6 mm or greater. For statistical purposes, these scores were divided into 2 subgroups according to the radiographic apex: acceptable (B, C, and D) and non-acceptable (A and E). Statistically significant differences were not found between the results of Apex and iPex in terms of acceptable and non-acceptable measurements (p>0.05) or in terms of the distance recorded from file tip and the radiographic apex (p>0.05). Apex and iPex EALs provided reliable measurements for WL determination for endodontic therapy.

Penetrability of AH Plus and MTA Fillapex After Endodontic Treatment and Retreatment: A Confocal Laser Scanning Microscopy Study

The aim of the study was to assess the penetrability of two endodontic sealers (AH Plus and MTA Fillapex) into dentinal tubules, submitted to endodontic treatment and subsequently to endodontic retreatment. Thirty ex vivo incisors were prepared using ProTaper rotary system up to F3 instrument and divided in three groups according to the endodontic sealer used for root canal filling: AH Plus (AHP), MTA Fillapex (MTAF), and control group (CG) without using EDTA previously to the root canal filling. Rhodamine B dye (red) was incorporated to the sealers in order to provide the fluorescence which will enable confocal laser scanning microscopy (CLSM) assessment. All specimens were filled with gutta‐percha cones using the lateral compaction technique. The specimens were submitted to endodontic retreatment using ProTaper Retreatment system, re‐prepared up to F5 instruments and filled with gutta‐percha cones and the same sealer used during endodontic retreatment. Fluorescein dye (green) was incorporated to the sealer in order to distinguish from the first filling. The roots were sectioned 2 mm from the apex and assessed by CLSM. No difference was found between the two experimental groups (P > 0.05). On the other hand, in the control group the sealers were not capable to penetrate into dentinal tubules after endodontic treatment (P > 0.05). In retreatment cases, none of the sealers were able to penetrate into dentin tubules. It can be concluded that sealer penetrability is high during endodontic treatment. However, MTA Fillapex and AH Plus do not penetrate into dentinal tubules after endodontic retreatment. Microsc. Res. Tech. 77:467–471, 2014.

Push-out bond strength of fiber posts to root dentin using glass ionomer and resin modified glass ionomer cements

Objective The purpose of this study was to assess the push-out bond strength of glass fiber posts to root dentin after cementation with glass ionomer (GICs) and resin-modified glass ionomer cements (RMGICs). Material and Methods Fifty human maxillary canines were transversally sectioned at 15 mm from the apex. Canals were prepared with a step back technique until the application of a #55 K-file and filled. Post spaces were prepared and specimens were divided into five groups according to the cement used for post cementation: Luting & Lining Cement; Fuji II LC Improved; RelyX Luting; Ketac Cem; and Ionoseal. After cementation of the glass fiber posts, all roots were stored at 100% humidity until testing. For push-out test, 1-mm thick slices were produced. The push-out test was performed in a universal testing machine at a crosshead speed of 0.5 mm/minute and the values (MPa) were analyzed by Kolmogorov-Smirnov and Levenes tests and by two-way ANOVA and Tukeys post hoc test at a significance level of 5%. Results Fiber posts cemented using Luting & Lining Cement, Fuji II LC Improved, and Ketac Cem presented the highest bond strength to root dentin, followed by RelyX Luting. Ionoseal presented the lowest bond strength values (P>0.05). The post level did not influence the bond strength of fiber posts to root dentin (P=0.148). The major cause of failure was cohesive at the cement for all GICs and RMGICs. Conclusions Except for Ionoseal, all cements provided satisfactory bond strength values.

Evaluation of Epoxy Resin Sealer After Three Root Canal Filling Techniques by Confocal Laser Scanning Microscopy

The aim of this study was to evaluate the penetration of endodontic sealer into the dentin tubules, the integrity of the sealer layer perimeter, and the sealer area at the apical third after different filling techniques by confocal laser scanning microscopy (CLSM). Forty‐five mandibular premolars were mechanically prepared with ProTaper files, until F5 file. Thereafter, they were filled with an epoxy‐resin sealer (AH Plus) mixed with Rhodamine B dye (0.1% proportion) and allocated in three groups: Group 1, single master cone; Group 2, cold lateral compaction; and Group 3, Thermafil. For confocal laser scanning microscopy analysis, the specimens were transversely sectioned at 4 mm from the apex. The images at ×10 and ×40 were analyzed by Imagetool 3.0 software. Significant differences were not found among the three experimental groups according the dentin‐impregnate area by the sealer (P = 0.68) and between the sealer and root canal perimeter (P = 0.18). However, root canal filling techniques were significantly different when apical sealer areas were compared (P = 0.001). Thermafil group showed smaller sealer areas (8.09%) while cold lateral compaction and gutta‐percha master cone showed similar areas (17.37 and 21.18%, respectively). The dentin‐impregnated area was not dependent on the root canal filling technique. Single master cone, cold lateral condensation and Thermafil techniques presented integrity of the sealer perimeter close to 100% and Thermafil resulted in a significantly thinner sealer layer. Microsc. Res. Tech. 75:1277–1280, 2012.

Micro-CT Evaluation of Root Filling Removal after Three Stages of Retreatment Procedure

The aim of this study was to quantify the residual filling material after filling removal, re-preparation with rotary or reciprocating files and passive ultrasonic irrigation (PUI). Twenty maxillary molars were prepared using ProTaper instruments up to F1. The teeth were filled with AH Plus and ProTaper gutta-percha points using the single-cone technique. Thereafter, the specimens were scanned using a micro-computed tomography system (Micro-CT #1). Then, the root canal filling was removed using ProTaper Retreatment files, and a new scan was performed (Micro-CT #2). The specimens were divided into two groups according to the instrument used for re-preparation: ProTaper rotary or WaveOne reciprocating files (Micro-CT #3). Finally, PUI was performed, and a new micro-CT scan was performed (Micro-CT #4). Intragroup and intergroup analyses were performed using Friedman and Dunns post hoc test and the Kruskal-Wallis and Dunn post hoc tests, respectively. Palatal canal presented the highest volume of residual filling material in all stages of endodontic retreatment (p<0.05). The main reduction of filling volume was achieved after using ProTaper Retreament (p<0.05). The amount of remaining filling material after using ProTaper Retreatment was similar to that achieved with rotary and reciprocating files and after PUI (p>0.05). Rotary and reciprocating files achieved similar removal of the root canal filling (p>0.05). The greatest reduction in filling material was achieved after using ProTaper Retreatment files. Rotary and reciprocating instruments and PUI did not improve the removal of root canal filling materials.