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Purpose: The objective of this study was to compare engine-driven instrumentation methods in relation to the appearance of defects in the walls of the root canal. Materials and methods: In total, 60 single-rooted human teeth, extracted for periodontal reasons, were conserved in Deltalab Eurotubo sterile A with 2% thymol until use. The teeth were decoronated and randomly divided into three groups (n = 20). In Group 1, canal negotiation was achieved with a size 10 K-file, followed by rotary pre-instrumentation with Pathfiles. Instrumentation with the ProTaper Universal system was carried through to a final file F4. In Group 2, the teeth were instrumented with the WaveOne Gold system according to the manufacturer's instructions. In Group 3, the teeth were left unprepared as control. After this, the canals were irrigated with 2 ml of distilled water and the teeth were conserved in distilled water. The samples were sectioned transversely before subsequent analysis on three levels. Defects were scored: 0 for no defects, 1 for cracks. Results: Reciprocating instrumentation with the WaveOne Gold Large instrument reduced by 30% the frequency of occurrence of cracks in the root canal walls in the coronal and apical thirds with respect to ProTaper F4 instrumentation (P < 0.05). There were no statistically significant differences between the systems in the incidence of cracks in the middle third. Conclusions: Instrumentation with WaveOne Gold generated fewer cracks in the coronal and apical thirds of the root canal compared with the ProTaper system. [ABSTRACT FROM AUTHOR]

Aim: To determine and classify the position of the mesial root canal orifices on the pulp chamber floor and examine their possible correlation with the radicular pattern in mandibular first molars. Materials and Methods In total, 110 extracted mandibular first molars were obtained and the positions of the orifices and the radicular pattern were observed using an operating microscope. Results: Of the mesial root canals, 61 (55.5%) had an independent pattern and 49 (44.5%) had a confluent radicular pattern. In canal orifices with symmetrical positions on the pulp chamber floor, the interorificial distance was key: 88% of canals were confluent at distances between 1 and 2 mm and 95.3% were independent at distances > 2 mm. In asymmetric positions, the canals had an independent pattern regardless of distance, with a percentage of 82.4%. Analysis of the independent and confluent radicular patterns showed a significant difference with the interorificial distance (P = 0.0004). Conclusion: A significant correlation was seen between the position of the mesial root canal orifices on the pulp chamber floor and an independent or confluent radicular pattern in the mandibular first molars. [ABSTRACT FROM AUTHOR]

Introduction: Dens invaginatus is a malformation of the tooth during embryonic development that presents in several morphological types. This article reports a case of a type II dens invaginatus with an extensive periradicular lesion that was treated successfully. Methods: Three-dimensional imaging, cone beam computed tomography (CBCT) was used to identify the morphology of dens invaginatus and to help devise a treatment plan. Nonsurgical and surgical endodontic treatments were performed to achieve a favourable outcome. Conclusions: Understanding both the configuration of the internal root canal and irregularities of the external root using CBCT can ensure predictable and successful results, as in this case. The 2-year follow-up showed complete healing of the periapical pathosis. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the fracture risk of ProTaper nickel-titanium (NiTi) rotary instruments under a continuous versus an alternating rotation when using the same instrumentation sequence. Plastic blocks with an embedded artificial root canal were used to investigate the fracture risk of NiTi instruments under a continuous rotation (360 degrees) and an alternating rotation (clockwise 60 degrees and counter-clockwise 45 degrees). A new instrument set was used until fracture of any instrument occurred. The number of times an instrument set and instrument type were used before fracture occurred was recorded and statistically evaluated. The results obtained in this investigation showed that the fracture risk of ProTaper instruments when used under continuous rotation was significantly higher (52.14% / P<0.001) compared with use under an alternating rotation. [ABSTRACT FROM AUTHOR]

Background: Laser irradiation has been introduced in endodontic treatment due to its bactericidal effect. The aim of this study is to evaluate the bactericidal efficacy of a 940 nm diode laser alone or in combination with 5% sodium hypochlorite (NaOCl) against mature biofilms of E. Faecalis. Methods: Sixty-eight (60 for the three groups, 4 for SEM and 4 as negative controls) single-rooted human central incisors were prepared and contaminated with E. Faecalis. After two weeks of incubation, specimens were randomly divided in three groups; group 1 (n =20), the teeth were irradiated with a 940 nm diode laser; group 2 (n=20), specimens were rinsed with 5%NaOC1; group 3 (n=20), the teeth were rinsed with 5% NaOC1 and then were irradiated with 940 nm diode laser. Four teeth were used to observe the biofllms by SEM. Intracanal bacteria sampling was done, and the samples were plated to determinate the CFU count. Results: At 24 hours and 7 days, group 3 showed a significant difference (P=0,02; P0,00) in disinfection if compared to group 1 but did not show this difference if compared to group 2 (P=1, P=0,66), although group 3 obtaining a more extensive disinfection. Groups 1 and 2 did not show difference after 24 hours (P=0,09) but showed a significant difference 7 days afterwards (P=0,04). Conclusion: The combination of sodium hypochlorite and diode laser light (940 nm) has a synergistic effect, intensifying the bactericidal action. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to evaluate the fracture and defects observed in ProTaper Next files discarded after a normal clinical use., Material and Methods: 571 ProTaper Next rotary instruments were collected after clinical use from the clinic of endodontics over 12 months. The length of the files was measured using a digital caliper to determine any fracture, later all the files were evaluated under a stereomicroscope to observe defects such as unwinding, curving or fracture. The data obtained were analyzed using a chi-square and z test., Results: 13.83% of the discarded files showed defects, the most frequent defect was fracture (7.53%). The highest rate of fracture was observed in the X1 (17.04) files (19.87%). The presence of deformations without fracture was also more frequent in the 17.04 file (11.8%)., Conclusions: Because of the relatively high incidence of deformation of smaller files, these instruments should be considered as a single use. It is important not to exceed the maximum uses recommended by the manufacturer to reduce the risk of cyclic fatigue, the main cause of fracture of the files (79.07%). It is also important to observe each file after use to discard small defects or fractures. Key words: Clinical use, deformation, fracture, M-Wire, ProTaper Next., Competing Interests: Conflict of interest statement: The authors have declared that no conflict of interest exist.

Background: One of the causative factors of root defects is the increased friction produced by rotary instrumentation. A high canal curvature may increase stress, making the tooth more susceptible to dentinal cracks. The purpose of this study was to evaluate dentinal micro-crack formation with the ProTaper NEXT and ProTaper Universal systems using LED transillumination, and to analyze the micro-crack generated at the point of maximum canal curvature., Material and Methods: 60 human mandibular premolars with curvatures between 30-49° and radii between 2-4 mm were used. The root canals were instrumented using the Protaper Universal® and Protaper NEXT® systems, with the aid of the Proglider® system. The obtained samples were sectioned transversely before subsequent analysis with LED transillumination at 2 mm and 8 mm from the apex and at the point of maximum canal curvature. Defects were scored: 0 for no defects; and 1 for micro-cracks., Results: Root defects were not observed in the control group. The ProTaper NEXT system caused fewer defects (16.7%) than the ProTaper Universal system (40%) ( P <0.05). The ProTaper Universal system caused significantly more micro-cracks at the point of maximum canal curvature than the ProTaper NEXT system ( P <0.05)., Conclusions: Rotary instrumentation systems often generate root defects, but the ProTaper NEXT system generated fewer dentinal defects than the ProTaper Universal system. A higher prevalence of defects was found at the point of maximum curvature in the ProTaper Universal group. Key words: Curved root, Micro-crack, point of maximum canal curvature, ProTaper NEXT, ProTaper Universal, Vertical root fracture., Competing Interests: Conflict of interest statement:The authors declare that no competing interests exist.

Background: Irrigation of the root canal system is an essential step in the endodontic treatment. The aim of this article is to introduce continuous apical negative-pressure ultrasonic irrigation (CANUI), a new irrigation concept, and compare the characteristics of this new technique with current devices for activating the irrigant., Material and Methods: CANUI is designed for cleaning and disinfecting the root canal system. The device consists of a tube inside another tube that allows the continuous ultrasonic exchange of fresh irrigant, as the irrigant is simultaneously aspirated apically. The coronal and apical tubes are 0.75 and 0.3 mm in diameter, respectively. It is composed of a nickel-titanium microcannula suitable for the working length of curved canals., Results: The CANUI technique has the advantages of apical negative pressure (to avoid apical extrusion of the irrigant) and continuous ultrasonic irrigation (continuous refreshment of the irrigant and forced introduction into the canal ramifications)., Conclusions: The CANUI technique could improve the irrigation technique of dentists to reach more disinfection in endodontic treatments. Key words: Apical negative pressure, continuous ultrasonic irrigation, irrigation in curved canals, irrigation systems., Competing Interests: Conflict of interest statement:The authors deny any conflict of interest.

Background: The efficacy of endodontic irrigation procedures can be compromised by the complexity of the root canal system. Delivering irrigants to the apical third of curved canals presents a particular challenge to endodontists. This study compared the effects of two ultrasonic irrigation techniques on the penetration of sodium hypochlorite into the main canal and simulated lateral canals of curved roots in extracted teeth., Material and Methods: Two sets of simulated lateral canals were created at 2, 4, and 6 mm from the working length in 60 single-rooted teeth (6 canals/tooth, n = 360 canals). The teeth were randomly divided into three experimental irrigation groups: group 1 (n = 20), positive pressure irrigation (PPI); group 2 (n = 20), passive ultrasonic irrigation (PUI); and group 3 (n = 20), continuous ultrasonic irrigation (CUI). To assess the irrigation solution penetration, 20% Chinese ink (Sanford Rotring GmbH, Hamburg, Germany) was added to a 5% sodium hypochlorite solution and delivered into the curved root canals. The penetration of contrast solution into the simulated lateral canals was scored by counting the number of lateral canals (0-2) penetrated to at least 50% of the total length., Results: The CUI group showed significantly higher ( P < 0.05) irrigant penetration into the lateral canals and into the apical third of the main canals. The PPI group showed significantly lower sodium hypochlorite penetration ( P < 0.001) into the main and lateral canals compared with that in the CUI and PUI groups. Significantly higher irrigant penetration was observed in the PUI group than the PPI group., Conclusions: Using CUI as the final rinse significantly increased the penetration of irrigant solution into the simulated lateral canals and apical third of curved roots. Key words: Continuous ultrasonic irrigation, curved root canals, passive ultrasonic irrigation, positive pressure irrigation, root canal irrigation., Competing Interests: The authors deny any confict of interest.

Objective: The aim of this study was to compare the scanning electron microscopic (SEM) morphology of root canal walls instrumented manually and mechanically with and without the application of Er:YAG laser., Methods: Single-rooted, human, extracted teeth were cut at the cementoenamel junction. The teeth were divided into four groups: teeth that were simply instrumented manually, those that were instrumented manually and laser treated, a group that was mechanically instrumented, and a fourth in which the teeth were mechanically instrumented and laser treated. After instrumentation, the teeth were split longitudinally to facilitate their evaluation by SEM., Results: The results show that the use of the Er:YAG laser is effective in removing the smear layer from root canal walls., Conclusions: The removal of the smear layer is essential to the success of endodontic treatment; the use of the Er:YAG laser combined with rotary and manual techniques improves the cleanliness of root canals.