Efeito do momento de imersão na alteração volumétrica do agregado trióxido mineral HP / Effect of the immersion moment at the volumetric alteration of the mineral trioxide aggregate HP

Introdução: A solubilidade é uma propriedade relaciona- da à dissociação dos constituintes do material, pela ação do contato com o líquido circundante. Introdução: O objetivo do presente estudo foi avaliar o efeito da hidratação durante a varredura com microtomografia (micro-TC) sobre a alteração volumétrica do MTA HP. Métodos: foram utilizados 20 dentes incisivos superiores de acrílico com cavidade retrógrada. O cimento MTA HP foi inserido na cavidade com um condensador Paiva. As amostras foram inspecionadas visualmente com uma lupa de 5x, para garantir que não permanecessem espaços vazios ou lacunas. Os espécimes foram divididos em dois grupos (n=10). Os dentes foram escaneados logo após o manuseio do MTA. Para o grupo com imersão em água, Eppendorf hidratado foi mantido com 1mL de água durante a varredura; no outro grupo, os dentes foram escaneados sem água. Nos dois grupos, os dentes foram imersos em água durante sete dias. Em seguida, os dentes foram escaneados novamente em micro-TC usando os mesmos parâmetros e condições de cada grupo. Foi realizada a reconstrução das imagens pelo software Nrecon e o volume de solubilidade, determinado pelo software CTan, analisando-se a variação volumétrica. Resultados: O grupo de corpos de prova escaneados imersos na água apresentou maior variação volumétrica, com diferenças estatisticamente significativas em relação ao grupo escaneado sem imersão. O escaneamento do corpo de prova imerso em água favorece uma maior perda volumétrica do material. Conclusão: Os estudos para avaliar a variação volumétrica de cimentos de silicato de cálcio devem ser feitos com imersão em água.

Introduction: Solubility is a property related to the dissocia- tion of the constituents of the material by the action of contact with the surrounding liquid, for this reason, the aim of this study was to evaluate the effect of the hydration during the scanning in the microtomography on the volumetric alteration of the MTA HP. Methods: Twenty acrylic teeth upper incisor with retrograde cavity were utilized. The MTA HP cement was inserted into the cavity using a Paiva condensor. The specimens were visually inspected with a 5x magnifying glass to ensure they did not remain void or gaps. The specimens were divided into 2 groups (n=10). The teeth were scanned shortly after handling the MTA. For the group with water immersion, hydrated Eppendorf was kept with 1mL the water during the scanning and the other group, the teeth were scanning without water. In the two groups the teeth were immersed into water during 7 days. Next the teeth were newly scanned in the Micro-CT using the same parameters and conditions of each group. Reconstruction of images by the Nrecon software and the solubility volume determined by the CTan, analyzing the volumetric change. Results: The group of specimens scanned immersed into the water presented higher volumetric change with statistically significant differences in relation the group scanned without immersion. The scanning of the specimen immersed in water favors the greater volumetric loss of the material. Conclusion: Studies to evaluate volumetric change of calcium silicate cements should be made immersed in wate

Comparison of efficiency of the retreatment procedure between Wave One Gold and Wave One systems by Micro-CT and confocal microscopy: an in vitro study.

INTRODUCTION: To compare, by Micro-CT and confocal laser scanning microscopy (CLSM), the ability of the Wave One Gold and Wave One systems to remove filling material from mesial canals of mandibular molars, effective time spent; quantity of extruded material, and percentage of sealer in the dentinal tubules after retreatment and re-obturation procedures. MATERIALS AND METHODS: Ten first mandibular molars (n = 20 mesial canals) were prepared and filled with gutta-percha and Endofill sealer mixed with Rhodamine B dye using the single cone technique. After 7 days, the canals were scanned using a high-definition micro-computer tomography with 19-mm voxel size and divided into two groups (n = 10) according to the system used in retreatment: group 1, Wave One (WO), and group 2, Wave One Gold (WG). After removing filling material with the primary file of each system, the WO 40/.08 and WG 35/.06 files were used. After using each file, a new scanning was performed and the residual filling material and extruded filling material were measured. The effective time spent to remove the canal filling was measured after each instrument. After retreatment, the teeth were re-obturated with gutta-percha and AH Plus sealer mixed with fluorescein dye using the single-cone technique. The roots were sectioned at 2, 4 and 6 mm and analysed by CLSM to measure the percentage of remaining sealer and the sealer of the new root canal filling. The data were statistically compared (P < 0.05). RESULTS: Both systems presented a similar volume of filling material remaining in the canals after the use of the two instruments, similar residual and new material in the dentinal tubules, and similar extrusion of material (P > 0.05). When using WO 25, the operator spent significantly less effective time than when using WG 25 (P < 0.05); however, use of WG 35 and WO 40 required a similar time to remove filling material from the canals (P > 0.05). CONCLUSIONS: Neither of the two systems removed all the filling material. The WG system presented similar ability in removing filling and extruded material in comparison with WO system. The effective time spent was shorter for WO 25 than for WG 25. CLINICAL RELEVANCE: Wave One Gold can be an alternative to perform retreatment considering that in comparison with Wave One, there was no difference in filling material removal capacity and extruded materials. There was only difference in the effective time spent, in which the operator spent more time with WG 25 than with WO 25.

Do different strains of E. faecalis have the same behavior towards intracanal medications in in vitro research?

The aim of this study was to evaluate the antimicrobial action of different endodontic pastes against Enterococcus faecalis ATCC 29212, isolated from the urinary tract, and compare the action with E. faecalis ATCC 4083, isolated from the root canal. For this purpose, dentin blocks were infected for 21 days with both bacteria at different time-intervals to ensure there would be no cross contamination. After this period, blocks were immersed in the test medications for 7 days, according to the following groups: CH/S, CH/P, CH/CMCP, CH/CHX, CH/DAP and TAP. Images of the samples were captured with a confocal microscope and the percentage of live cells was computed by means of the Bioimage program. The ATCC 29212 strain was shown to be more resistant to CH/SS, Calen, CH/DAP, and TAP than the ATCC 4083 strain. The antimicrobial action of the medications against each strain were divergent concerning the order of susceptibility. The authors concluded that the strains behaved in a different manner: in general, those extracted from the urinary tract were more resistant to the tested medications. Therefore, when E. faecalis must be used for in vitro research in endodontics, we suggest the use of ATCC 4083 strain to obtain results that are closer to the clinical reality.

Effect of the irrigation protocols on the elimination of dentin debris from simulated lateral canals / Efeito do método de irrigação na eliminação de debris dentinários em canais late-rais simulados

Objective: Computed microtomography was used to evaluate the capacity of debris removal from simulated lateral canals, in conventional irrigation, passive ultrasonic irrigation (PUI), continuous passive irrigation (CUI), Endoactivator and EasyClean, for both types of motion (continuous and reciprocating). Material and Methods: Sixty acrylic incisors with 3 simulated lateral canals per tooth (cervical, middle and apical third) were instrumented with Reciproc 40/06 and then filled with dentin debris. The teeth were scanned and divided into 6 groups (n = 10) according to the irrigation protocol: G1 - conventional, G2 - PUI, G3 - CUI, G4 - Endoactivator, G5 - EasyClean continuous rotation and G6 - EasyClean reciprocating. After the irrigation protocols, the samples were scanned again. The initial and final volume images were analyzed and the percentage of debris removal were found for each group in all levels. Results: There were significant differences between the initial and final volume of debris after the protocols, with the exception of conventional irrigation group in the apical and cervical thirds, EasyClean reciprocating in the middle and cervical thirds, and CUI in the middle third. In the analysis between the groups: in the apical third, Endoactivator and PUI removed more debris than CUI (p < 0.05); in the middle and cervical thirds, PUI was more efficient than conventional irrigation, EasyClean reciprocating and CUI (p < 0.05). Conclusion: No method completely removed the debris. PUI was the method that showed greater effectiveness in cleaning the lateral canals. (AU)

Objetivo: O objetivo desse estudo foi avaliar a capacidade de remoção de debris de canais laterais simulados através da microtografia computadorizada (microCT), na irrigação convencional, ultrassônica passiva (IUP), ultrassônica contínua (IUC), Endoactivator e EasyClean, para os dois tipos de movimento (contínuo ou alternado). Material e Métodos: Sessenta incisivos de acrílico com três canais late-rais simulados por dente (terço cervical, médio e apical) foram instrumentados com Reciproc 40/06 e preenchidos com debris de dentina bovina. Os dentes fo-ram escaneados e divididos em 6 grupos (n = 10): G1 - convencional, G2 - IUP, G3 - IUC, G4 - Endoactivator, G5 - EasyClean rotação continua e G6 - EasyClean reciprocante. Depois do protocolo de irrigação, as amostras foram novamente escaneadas. O volume inicial e final das imagens foram analisados e o percentual de debris removidos foram encontrados para cada grupo nos três terços. Resultados: Todos os grupos obtiveram diferenças significantes após o proto-colo de irrigação, com exceção do grupo da irrigação convencional nos terços apical e cervical, EasyClean reciprocante (médio e cervical) e IUC no terço médio. Na análise intragrupo para o terço apical, EndoActivator e IUP removeram mais debris que IUC (p<0,05); no médio e cervical, IUP foi mais eficiente que a irrigação convencional, EasyClean reciprocante e IUC (p<0,05). Conclusão: Nenhum método foi capaz de remover completamente os debris. A irrigação ultrassônica passiva foi a que demonstrou melhor efetividade na limpeza dos canais laterais. (AU)

Do different strains of E. faecalis have the same behavior towards intracanal medications in in vitro research?

Abstract: The aim of this study was to evaluate the antimicrobial action of different endodontic pastes against Enterococcus faecalis ATCC 29212, isolated from the urinary tract, and compare the action with E. faecalis ATCC 4083, isolated from the root canal. For this purpose, dentin blocks were infected for 21 days with both bacteria at different time-intervals to ensure there would be no cross contamination. After this period, blocks were immersed in the test medications for 7 days, according to the following groups: CH/S, CH/P, CH/CMCP, CH/CHX, CH/DAP and TAP. Images of the samples were captured with a confocal microscope and the percentage of live cells was computed by means of the Bioimage program. The ATCC 29212 strain was shown to be more resistant to CH/SS, Calen, CH/DAP, and TAP than the ATCC 4083 strain. The antimicrobial action of the medications against each strain were divergent concerning the order of susceptibility. The authors concluded that the strains behaved in a different manner: in general, those extracted from the urinary tract were more resistant to the tested medications. Therefore, when E. faecalis must be used for in vitro research in endodontics, we suggest the use of ATCC 4083 strain to obtain results that are closer to the clinical reality.

Comparative Effectiveness of New Mechanical Irrigant Agitating Devices for Debris Removal from the Canal and Isthmus of Mesial Roots of Mandibular Molars.

INTRODUCTION: The aim of this study was to compare the effectiveness of Easy Clean (Easy Dental Equipment, Belo Horizonte, MG, Brazil) in continuous and reciprocating motion, passive ultrasonic irrigation (PUI), Endoactivator systems (Dentsply Maillefer, Ballaigues, Switzerland), and conventional irrigation for debris removal from root canals and isthmus. METHODS: Fifty mesial roots of mandibular molars were embedded in epoxy resin using a metal muffle; afterward, the blocks containing the roots were sectioned at 2, 4, and 6 mm from the apex. After instrumentation, the roots were divided into 5 groups (n = 10) for application of the final irrigation protocol using Easy Clean in continuous rotation, Easy Clean in reciprocating motion, PUI, Endoactivator, and conventional irrigation. Scanning electron microscopic images were taken after instrumentation and after the first, second, and third activation of irrigating solution to evaluate the area of remaining debris with image J software (National Institutes of Health, Bethesda, MD). RESULTS: The protocol of 3 irrigating solution activations for 20 seconds provided better cleaning of the canal and isthmus. On conclusion of all procedures, analysis of the canals showed a statistical difference only at 2 mm; the Easy Clean in continuous rotation was more efficient than conventional irrigation (P < .05). On conclusion of all steps, the largest difference was observed in the isthmus in which the Easy Clean in continuous rotation was more effective than conventional irrigation at the 3 levels analyzed and the Endoactivator at 4 mm (P < .05). The PUI promoted greater cleaning than conventional irrigation at 6 mm (P < .05). There was no statistical difference between Easy Clean in continuous rotation, Easy Clean in reciprocating motion, and PUI (P > .05). CONCLUSIONS: Irrigating solution activation methods provided better cleaning of the canal and isthmus, especially the Easy Clean used in continuous rotation. The protocol of 3 irrigating solution activations for 20 seconds favored better cleaning.

Influência do contato com sangue e soro fisiológico na solubilidade, pH e constituição química do MTA / Influence of contact with blood and saline on solubility, pH and chemical composition of MTA

Objetivo: o objetivo deste estudo foi avaliar a solubilidade, pH e composição química do MTA branco em contato com sangue e soro fisiológico. Métodos: trinta réplicas de incisivos centrais superiores em acrílico, com retrocavidades com 3 mm de profundidade, foram preenchidas com MTA branco. Os espécimes foram individualmente inseridos em microtubos e divididos em três grupos (n = 10): no Grupo 1, as amostras não foram expostas a líquidos (grupo controle); no grupo 2, os microtubos receberam 1 mL de soro fisiológico; e no Grupo 3, receberam 1 mL de sangue humano fresco. As amostras foram armazenadas a 37°C durante 24 horas. A solubilidade foi avaliada volumetricamente, de modo que os espécimes foram escaneados por Micro-CT e individualmente imersos em 10 mL de água ultrapura; após 168 horas, novos escaneamentos foram realizados. O nível de pH foi mensurado após 168 horas. Secções das amostras com 2 mm de espessura foram analisadas por meio de espectroscopia de energia dispersiva, para avaliar a composição iônica. Os dados foram analisados estatisticamente pelos testes ANOVA e Tukey. Resultados: a solubilidade foi similar (p > 0,05) para todos os grupos. Após 168 horas, o pH foi significativamente maior para o Grupo 2, em comparação ao Grupo 3 (p < 0,05). Quanto à composição iônica, foi encontrada maior concentração de cálcio e o contato com sangue não interferiu na liberação de íons de cálcio. Conclusão: o contato do sangue e soro fisiológico com o MTA não influenciou na solubilidade, ambos favoreceram um pH alcalino, com o aumento da liberação de íons cálcio, com pequenas variações na composição iônica.