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Background: The aim of this study was to compare the WaveOne Gold and ProTaper Next systems regarding the time spent preparing simulated canals performed by an inexperienced student. Material and Methods: 80 simulated L-shaped canals were randomly divided into two groups (n = 40) and numbered in order of instrumentation. Canals were instrumented with WaveOne Gold (group 1) and ProTaper Next (group 2) systems. The effective instrumentation time and the number of instrumentation cycles were recorded. All procedures were performed by the same operator. Statistical analysis was obtained by the Mann-Whitney, Kruskal-Wallis test with significance of p, (undefined)

[Excerpt] The success rates of endodontic treatment can reach levels from 86% to 98% (Abitbol et al., 2003). However, apical periodontitis may still persist or develop after treatment due to various factors, namely coronal leakage, caries or fractures, thus enabling reinfection by microorganisms of the oral cavity or proliferation of microorganisms in persisting endodontic infections (Siqueira, 2001, Correia-Sousa et al., 2015, Melo et al., 2017). Endodontic retreatment aims to reduce the bacterial load to a level that enables periapical healing. Nevertheless, its outcome is poor – about 70.9–83% (Torabinejad et al., 2009, Ng et al., 2011). The cleanliness of root canals cannot be accurately assessed through conventional periapical radiography or magnifying devices, but residual gutta-percha is systematically found in micro-CT scans after retreatment (Oltra et al., 2017). Chloroform and xylene have been widely used as endodontic solvents but concerns about their toxicity and potential carcinogenic effect led to seeking alternatives (Tamse et al., 1986, Metzger et al., 2000, Vajrabhaya et al., 2004, Magalhaes et al., 2007). Essential oils, like eucalyptol or orange oil, are one of the most common alternative groups of solvents used to enhance the dissolution or softening of gutta-percha. However, although they are considered less toxic, they are also reported as less powerful (Zaccaro Scelza et al., 2006, Faria-Junior et al., 2011, Martos et al., 2011). Studies show that, despite all the currently available technology, it is still not possible to achieve the complete removal of the potentially infected filling materials, which prevents total debridement and effective bacteria control (Alves et al., 2016, Keles et al., 2016, Rossi-Fedele and Ahmed, 2017). Although solvents have been indicated to prevent complications, such as ledges or perforations, in retreatment procedures, the literature reports that their use may hinder the cleaning of the root canal (Horvath et al., 2009). Retreatment can be carried out with or without solvents, but professionals often prefer to remove gutta-percha mainly with instrumentation, even though this may be a longer and less predictable procedure (Sae-Lim et al., 2000, Khalilak et al., 2013). Thus, endodontic solvents have almost fallen out of use. A new insight on endodontic retreatment seems to be necessary. [...], (undefined)

Background: Candida albicans is the most prevalent fungi isolated in endodontic infections. In this study, the ability of C. albicans biofilm to tolerate the novel solvent mixtures methyl ethyl ketone (MEK)/tetrachloroethylene (TCE) and MEK/orange oil (OOil) sequentially to the standard irrigation of sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic (EDTA) was evaluated. Methods: Biofilm cell cultures of C. albicans SC 5314 were treated sequentially with NaOCl and EDTA and exposed to MEK/TCE or MEK/OOil. The effect of the antimicrobial treatment was evaluated using the disk diffusion method for planktonic culture, and the enumeration of colony-forming units (CFUs) and scanning electron microscope (SEM) for biofilm cell culture. Results: C. albicans mature biofilm (24 h) was significantly reduced in biomass and cell viability after solvent mixtures exposure, compared with the previous NaOCl and EDTA treatments. MEK/OOil combination caused a total reduction of biofilm, while with MEK/TCE, there was a 3-log (CFU/cm2) reduction compared with the sequence NaOCl and EDTA, and a 4-log (CFU/cm2) reduction compared with the control. Conclusions: The additional exposure of a preformed 24 h C. albicans biofilm to novel solvent mixtures MEK/TCE and MEK/OOil caused a positive antibiofilm impact, overcoming the performance of the conventional endodontic irrigating protocol., This article was supported by National Funds through FCT-Fundação para a Ciência e a Tecnologia, I.P., within CINTESIS, R&D Unit (reference UIDB/4255/2020). This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and grant ref 2020.05720.BD for Liliana Fernandes; BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020-Programa Operacional Regional do Norte., info:eu-repo/semantics/publishedVersion

This study aimed to compare the efficacy of XP-endo Finisher R and IrriSafe, with a solvent mixture of Methyl ethyl ketone/Tetrachloroethylene (MEK/TCE), in the removal of root filling residues. Twenty-four human mandibular incisors were pair-matched by micro-computed tomography according to volume and aspect ratio. After retreatment, specimens were allocated to two experimental groups (n = 12), according to the supplementary instrument used. The volume of residual filling material after each irrigating step and the time for retreatment was calculated. Statistical analyses were carried out using Mann–Whitney test, with a significance level of 5%. The volume of initial root canal filling material between the groups was similar (p > 0.05). With the final irrigation protocol (NaOCl and EDTA) the volume of the filling remnants decreased significantly (p 0.05). The additional solvent mixture MEK/TCE increased the efficiency of filling materials reduction, regardless of the agitating instruments employed, IrriSafe or XP-endo Finisher R (p

The aim of this study was to compare the effects of new irrigation solvent mixtures with Methyl ethyl ketone (MEK)/Tetrachloroethylene (TCE) and MEK/Orange oil (OOil), and different agitation techniques on dentin hardness. One hundred forty-four mandibular teeth were prepared and standardized, with each root’s middle part transversely sectioned. Initial hardness was measured using a Vickers microhardness tester. Specimens were divided into four groups of agitation techniques (n = 36): no agitation; EndoActivator; IrriSafe; and XP-endo Finisher R. Each group was subdivided into six subgroups of irrigation protocols (n = 6): saline solution; NaOCl + EDTA; NaOCl + EDTA + MEK/TCE; MEK/TCE; NaOCl + EDTA + MEK/OOil; MEK/OOil. Final hardness was measured. The irrigation protocols NaOCl + EDTA, NaOCl + EDTA + MEK/TCE, and NaOCl + EDTA + MEK/OOil significantly decreased dentin hardness, while MEK/OOil increased it (p

Objectives: This study reports the efficacy of two solvent mixtures on the dissolution of gutta-percha and AH Plus sealer, together with the cytotoxicity. Methods: Methyl ethyl ketone (MEK), orange oil, tetrachloroethylene, MEK/tetrachloroethylene (1:1), MEK/orange oil (1:1), and chloroform (control) were tested. Twelve groups (n = 15) of standardized stainless-steel molds filled with softened gutta-percha cones and twelve (n = 15) filled with AH Plus were immersed in the corresponding mixture or individual solvent, in an ultrasonic bath, for either 2 or 5 min. The effect of the solvents was assessed qualitatively by a topographical analysis (scanning electron microscopy) and chemical analysis (Fourier transform infrared spectroscopy), and quantitatively by a weight loss and viscoelastic property (dynamic mechanical analysis) evaluation. The cytotoxicity was assessed on MG63 human osteoblastic cells. Results: The mixtures did not show the formation of new compounds. Both presented significantly higher efficacies compared to their individual solvents, suggesting a synergistic effect. Their dissolution efficacy was similar to that of chloroform, showing high cytocompatibility. Conclusions: The proposed strategy, incorporating ultrasound agitation and profiting from the synergy of adequate solvents, might enhance root canal cleanliness allowing a single-step procedure to dissolve gutta-percha and the sealer remnants, while assuring cytocompatibility with the periapical tissues., This article was supported by National Funds through FCT—Fundação para a Ciência e a Tecnologia,I.P.-V., within CINTESIS, R & D Unit (reference UIDB/4255/2020).

Synthetic cathinones abuse remains a serious public health problem. Kidney injury has been reported in intoxications associated with synthetic cathinones, but the molecular mechanisms involved have not been explored yet. In this study, the potential in vitro nephrotoxic effects of four commonly abused cathinone derivatives, namely pentedrone, 3,4-dimethylmethcatinone (3,4-DMMC), methylone and 3,4-methylenedioxypyrovalerone (MDPV), were assessed in the human kidney HK-2 cell line. All four derivatives elicited cell death in a concentration- and time-dependent manner, in the following order of potency: 3,4-DMMC >> MDPV > methylone ≈ pentedrone. 3,4-DMMC and methylone were selected to further elucidate the mechanisms behind synthetic cathinones-induced cell death. Both drugs elicited apoptotic cell death and prompted the formation of acidic vesicular organelles and autophagosomes in HK-2 cells. Moreover, the autophagy inhibitor 3-methyladenine significantly potentiated cell death, indicating that autophagy may serve as a cell survival mechanism that protects renal cells against synthetic cathinones toxicity. Both drugs triggered a rise in reactive oxygen and nitrogen species formation, which was completely prevented by antioxidant treatment with N‑acetyl‑L‑cysteine or ascorbic acid. Importantly, these antioxidant agents significantly aggravated renal cell death induced by cathinone derivatives, most likely due to their autophagy-blocking properties. Taken together, our results support an intricate control of cell survival/death modulated by oxidative stress, apoptosis and autophagy in synthetic cathinones-induced renal injury.

Background: This work aimed to evaluate the efficacy of sonic agitation of a binary mixture of solvents (methyl ethyl ketone/tetrachloroethylene) on filling remnants removal and compare the effects of solvent agitation with the enlargement to the next instrument size. Methods: Twenty-four mandibular incisors were prepared with ProTaper Next (X1, X2) and obturated with the single-cone technique and AH Plus sealer. The teeth were retreated with ProTaper Universal Retreatment and ProTaper Next and divided into two groups (n = 12) according to the final instrument (X3 or X4). All canals were submitted to a supplementary procedure consisting of a mixture of solvents―methyl ethyl ketone/tetrachloroethylene, agitated with EndoActivator. The volume of filling remnants was assessed through micro-computed tomography in the apical 5 mm. Statistical analysis was performed with a significance level of 5%. Results: The supplementary procedure of agitation of the solvent mixture was beneficial in both groups (p &lt, 0.05). There were no statistically significant differences between canals re-prepared until X4 and canals re-prepared until X3 plus solvent (p &gt, 0.05). Conclusions: An additional step with a two-solvent solution potentiated by EndoActivator showed to be very effective for the removal of gutta-percha and resinous sealer remnants from apical root canals of mandibular incisors, avoiding further enlargement.

Objective:This study aimed to evaluate the influence of the instrument regarding the apical fit and type of the alloy and coronal preflaring procedures in the accuracy of Propex Pixi.Methods: A total of 40 extracted human single-rooted permanent teeth with apical diameters of 200 mu m were selected. A #10 K-file was inserted in the root canal until its end could be observed by a dental microscope to obtain the actual working length (WL). Electronic measurements were performed using Propex Pixi to the root apex ("0.0"). Different file alloys (stainless steel [SS] and nickel titanium [NiTi]) and sizes (#10, #15, and #20) were used before and after coronal flaring. Statistical analysis was performed by a factorial analysis of variance (P, (undefined)

This work explored a novel approach to enhance the antibacterial activity of commercial Gutta-percha (GP) cones, the most commonly used core filling materials used in endodontic treatment. The reported procedure involved an argon (Ar) plasma treatment (PT) of the GP cone surface, followed by the deposition of a ZnO thin film by magnetron sputtering. The resulting surfaces were evaluated for surface topography, antibacterial activity against Enterococcus faecalis and Staphylococcus aureus, and cytocompatibility with human osteoblastic cells. GP cones treated with NaOCl, a routine chair-side protocol, were also tested as reference. The deposition of a ZnO film on pristine GP cones increased its antibacterial activity. Cones pre-treated with Ar-plasma (PT) and coated with the ZnO thin film presented significantly higher antibacterial activity than that observed on the pristine and, also, compared to the ZnO coated cones. The higher antibacterial activity of PT + ZnO cones appears related to the major effects induced by the PT pre-treatment on the cone surface endowing the deposited ZnO film with a homogeneous nanostructured topography that greatly improved surface reactivity. The modified GP cones maintained an appropriate cytocompatibility with human cells. This novel approach provides ready-to-use cones with enhanced antibacterial activity, improving a strict asepsis protocol during endodontic treatment and preventing secondary endodontic infections., Financial support from the European Union (FEDER funds POCI/01/0145/FEDER/007265) and National Funds (FCT/MEC, Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência) under the Partnership Agreement PT2020 UID/QUI/50006/2013 is acknowledged. This research was also sponsored by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 and FCT Project 9471 - RIDTI, co-funded FEDER and with reference PTDC/FIS-NAN/1154/2014. J. Borges acknowledges FCT for his Postdoc Grant (SFRH/BPD/117010/2016) and C. Lopes acknowledges FCT for his PhD Grant (SFRH/BD/103373/2014)., info:eu-repo/semantics/publishedVersion

Introduction: The purpose of this study was to evaluate the use of solvents that are not traditionally used in dentistry for the dissolution of an epoxy resin based sealer and the effect of ultrasonic agitation (UA). Methods: The dissolution of the AH Plus sealer (Dents ply DeTrey, Konstanz, Germany) and the effect of UA in various solvents (eucalyptol, xylene, chloroform, EndoSolv R [Septodont, Cedex, France], EndoSolv E [Septodont], methyl ethyl ketone [MEK], and ethyl acetate) were quantified. The dissolving capacity was assessed by weight loss, Vicker microhardness, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results were compared with factorial analysis of variance using IBM SPSS Statistics 23.0 software (IBM, Armonk, NY), considering a 0.05 significance level. A preliminary ex vivo study was performed in extracted teeth, with MEK activated by UA as the final irrigation after mechanical removal of the filling material. SEM was used for assessing the cleanliness of the root canal walls. Results: The new solvent proposals, ethyl acetate and MEK, exhibited high dissolution ability, almost reaching chloroform. UA increased dissolution. Vicker values corroborated the dissolution assays. SEM and XRD revealed that solvents affected mainly the organic component of the sealer. Ex vivo results confirmed the immersion model findings. Conclusions: MEK and ethyl acetate proved to be excellent alternatives to chloroform or xylene solvents. MEK presented a high sealer dissolving ability in a short period, especially with UA, without the potential hazards of chloroform, suggesting it is a good approach to AH Plus sealer's dissolution empowered by UA. These results should encourage further studies in order to confirm their clinical relevance., Supported by Fundacao Para a Ciencia e a Tecnologia through the Project UID/EMS/00285/2013., info:eu-repo/semantics/publishedVersion

Although several surgical techniques have been reported, no study has yet reported alternative strategies for endodontic treatment of autogenous transplanted teeth. Therefore, the aim of this clinical report is to present the long-term endodontic outcome of a nonvital autogenously transplanted third molar treated with an Er,Cr:YSGG laser and radial firing tips (RFTs).Autogenous tooth transplantation can be considered an alternative to restore edentulous areas and, in donor's teeth with complete root formation, root canal treatment should be performed up to 14 days following transplantation. In the present case report, the patient returned only after 6 months, with clinical and radiological signs of apical periodontitis (AP) associated with the transplanted tooth.Instead of traditional endodontic chemical irrigants or medications, the protocol for smear-layer removal and root canal disinfection was based on intracanal irradiation with an Er,Cr:YSGG laser and RFTs.After 3-years' follow-up, the complete reestablishment of the periodontal ligament and the arrest of the resorptive process could be noticed.This protocol has shown to be effective for the endodontic treatment of a transplanted multi-rooted tooth with AP. Further randomized clinical trials should be conducted to clearly demonstrate the effectiveness of this laser-assisted endodontic protocol.

Objetivos Este estudo teve como objetivos investigar a prevalência da fratura dos instrumentos endodônticos pelos alunos do Mestrado Integrado em Medicina Dentária da Faculdade de Medicina Dentária da Universidade do Porto e determinar possíveis fatores associados. Métodos Um estudo retrospetivo foi conduzido através da análise dos relatórios clínicos e radiográficos dos tratamentos endodônticos realizados pelos alunos de pré-graduação do Mestrado Integrado em Medicina Dentária da Faculdade de Medicina Dentária da Universidade do Porto entre setembro de 2008 e julho de 2012. Um total de 1.162 tratamentos (2.177 canais) em dentes molares (420), pré-molares (365) e dentes anteriores (377) foram avaliados. Dados adicionais como tipo e localização do dente, primeiro tratamento versus retratamento, tipo de instrumento fraturado, localização do instrumento retido e procedimento clínico adotado, foram processados. A análise estatística foi efetuada no programa R para intervalos de confiança de 95% e níveis de significância 0,05 para o teste chi-quadrado de Pearson. Resultados A prevalência de instrumentos fraturados durante o tratamento endodôntico pelos alunos de pré-graduação foi de 1,64%. Essa prevalência foi estatisticamente superior no terço apical (63,2%) relativamente ao terço médio (21,0%) e coronal (15,8%) (p< 0,05). A frequência da fratura dos instrumentos revelou-se superior nos casos de retratamento (p< 0,05). Conclusões A prevalência dos instrumentos endodônticos fraturados pelos alunos em pré-graduação foi baixa. Uma maior prevalência de fraturas foi associada aos casos de retratamento endodôntico e nas situações decorrentes da preparação do terço apical., Objectives: The purpose of this study was to investigate the prevalence of instrument fracture by undergraduate students of Dentistry of Faculdade de Medicina Dentaria da Universidade do Porto and establish possible associated fracture variables.Methods: A retrospective study was conducted by reviewing the clinical and radiographic reports of root canal treatments performed by undergraduate students of the Master Degree in Dentistry of Faculdade de Medicina Dentaria da Universidade do Porto between September 2008 and July 2012. A total of 1162 endodontic cases (2177 root canals) 420 molars, 365 premolars and 377 anterior teeth were evaluated. Additional data such as type and location of the tooth, initial therapy versus retreatment, type of instrument fractured, level of the retained instrument and management were recorded. Statistical analysis was performed with R program to 95% confidence intervals and 0.05 significance levels for the X-squared test.Results: The overall prevalence of instrument fracture during root canal treatment by undergraduate students was 1.64%. The prevalence of instruments fractured in the apical third (63.2%) was significantly higher when compared with middle (21.0%) and coronal (15.8%) thirds (p< 0.05). The fracture frequency was higher in retreatment cases in relation to initial therapies (p< 0.05).Conclusions: The prevalence of endodontic instrument fracture by the undergraduate students was low. A higher prevalence rate was associated in retreatment cases and in the apical third.