Percentage of gutta-percha in mesial canals of mandibular molars obturated by lateral compaction or single cone techniques

The aim of this study was to compare the percentage of gutta-percha (PGP) in mesial root canals of mandibular molars obturated with LC (Lateral Compaction) or SC (Single Cone) ProTaper Universal System techniques at different levels of the root. Mesial root canals of 20 human permanent molars with similar anatomical characteristics were instrumented using the ProTaper Universal rotary system technique until the F2 instrument, with 20 canals filled by SC ProTaper Universal technique and 20 canals by the LC technique. The mesial roots were sectioned transversely to 3, 5, and 7 mm from the root apex. Digital images of specimens were obtained at MIC-D digital microscope in increases of 30 to 35X. The gutta-percha area was measured using ImageTool software. Data were analyzed using two-way ANOVA and Bonferroni test (a = 0.05). The SC technique provided greater PGP than the LC technique in the apical third (3 mm) (P < 0.001). In the other thirds (5 and 7 mm) there was no statistical difference between the two techniques regarding the PGP (P > 0.05). There was no statistically significant difference between thirds of the root canal for both techniques (P > 0.05). It was concluded that SC technique provided greater PGP than the LC technique in the apical third of mesial root canals of mandibular molars. There was no difference between the two techniques regarding the PGP in the cervical and middle thirds. Microsc. Res. Tech. 75:12291232, 2012. (C) 2012 Wiley Periodicals, Inc.

Root Canal Area Increase Promoted by the EndoSequence and ProTaper Systems: Comparison by Computed Tomography

Introduction: The aim of this study was to compare the increase of the root canal area after instrumentation with EndoSequence or ProTaper rotary systems. Methods: Twenty-two mesial root canals from mandibular molars were instrumented. Teeth were mounted on a base, numbered, and divided into 2 groups; teeth from 1-11 (PT group) were instrumented by using the ProTaper system, and teeth from 12-22 (ES group) were instrumented by using the EndoSequence system. Cone beam computed tomography was performed on all teeth before and after instrumentation. Measurements at 3,5, and 7 mm as well as differences in instrument performance were statistically compared by the Student t test at 5% significance level. Results: Both systems increased significantly the root canal area (P < .05) at all levels. Comparison between the rotary systems showed significantly greater increase (P < .05) for EndoSequence at 3 mm, with no statistically significant difference (P < .05) at the other levels. Conclusions: Both rotary systems increased significantly the root canal area. (J Endod 2010;36:1179-1182)

Bond strength of different endodontic sealers to dentin: push-out test

Objective: The aim of this in vitro study was to evaluate the bond strength of different root canal sealers to dentin. Material and Methods: Forty extracted single-rooted human teeth were examined and the coronal and middle thirds of the canals were prepared with a 1.50 mm post drill (FibreKor Post System, Pentron). The teeth were allocated in two experimental groups, irrigated with 2.5% NaOCl+17% EDTA or saline solution (control group) and instrumented using Race rotary files (FKG) to a size #40 at the working length. Then, the groups were divided into four subgroups and filled with Epiphany sealer (Group 1), EndoREZ (Group 2), AH26 (Group 3) and Grossman's Sealer (Group 4). After 2 weeks of storage in 100% humidity at 37 degrees C, all teeth were sectioned transversally into 2-mm-thick discs. Push-out tests were performed at a cross-head speed of 1 mm/min using a universal testing machine. The maximum load at failure was recorded and expressed in MPa. Results: Means (+/- SD) in root canals irrigated with 2.5% NaOCl and 17% EDTA were: G1 (21.6 +/- 6.0), G2 (15.2 +/- 3.7), G3 (14.6 +/- 4.5) and G4 (11.7 +/- 4.1). Two-way ANOVA and Tukey's test showed the highest bond strength for the Epiphany's group (p < 0.01) when compared to the other tested sealers. Saline solution decreased the values of bond-strength (p < 0.05) for all sealers. Conclusion: Epiphany sealer presented higher bond strength values to dentin in both irrigating protocols, and the use of 2.5% NaOCl and 17% EDTA increased the bond strength values for all sealers.

Morphometrical analysis of cleaning capacity of a hybrid instrumentation in mesial flattened root canals

The cleaning capacity of hybrid and rotary instrumentation techniques in mesial flattened canals of mandibular first molars was evaluated by morphometrical analysis in this study. Twenty human mandibular first molars were randomly assigned into two groups, according to instrumentation technique, as follows: group 1, instrumentation with ProTaper Starter Kit (Dentsply/Maillefer) rotary system; group 2, manual instrumentation using K files (Dentsply/Maillefer) by crown-down technique in middle and apical thirds, cervical preparation with Gates-Glidden #1 and #2 (Dentsply/Maillefer) burs, and to finalise the preparation, ProTaper F2 and F3 rotary files. Serial transverse cross-sections (5 mu m) of the apical third, stained with hematoxylin and eosin, were analysed at 100 x original magnification. The images were submitted to morphometrical analysis with an integration grid to determine the percentage of root canal area with debris. Statiscal analysis (t-Student, P < 0.05) showed significant difference between the techniques (P < 0.05), although neither completely cleaned the root canal.

Clinical microscopic analysis of protaper retreatment system efficacy considering root canal thirds using three endodontic sealers

To evaluate the efficacy of ProTaper Universal rotary retreatment system and the influence of sealer type on the presence of filling debris in the reinstrumented canals viewed in an operative clinical microscope. Forty-five palatal root canals of first molars were filled with gutta-percha and one of the following sealers: G1, EndoFill; G2, AH Plus; G3, Sealapex. The canals were then reinstrumented with ProTaper Universal rotary system. Roots were longitudinally sectioned and examined under an operative clinical microscope (10x), and the amount of filling debris on canal walls was analyzed using the AutoCAD 2004 software. A single operator used a specific software tool to outline the canal area and the filling debris area in each third (cervical, middle, and apical), as well as the total canal area. Data were analyzed by Kruskal-Wallis test and Tukey test at P < 0.05. Sealapex demonstrated significant differences in the average of filling debris area/canal among the 3 thirds. This group revealed that apical third showed more debris than the both cervical and middle third (P < 0.0001). Endofill presented significantly more filling debris than Sealapex in the cervical third (P < 0.05). In the middle (P = 0.12) and apical third (P = 0.10), there were no differences amongst groups. Debris was left in all canal thirds, regardless of the retreatment technique. The greatest differences between techniques and sealers were found in the cervical third. Microsc. Res. Tech. 75:12331236, 2012. (C) 2012 Wiley Periodicals, Inc.

Mixing and motion of rice particles in a rotating drum

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ultrasonic versus high-speed cavity preparation: Analysis of increases in pulpal temperature and time to complete preparation

Statement of problem. The use of ultrasonic tips has become an alternative for cavity preparation. However, there are concerns about this type of device, particularly with respect to intrapulpal temperatures and cavity preparation time.Purpose. The purpose of this study was to analyze pulpal temperature increases generated by an ultrasonic cavity preparation with chemical vapor deposition (CVD) tips, in comparison to preparation with a high-speed handpiece with a diamond rotary cutting instrument. The time required to complete the cavity preparation with each system was also evaluated.Material and methods. Thermocouples were positioned in the pulp chamber of 20 extracted human third molars. Slot-type cavities (3 x 3 x 2 mm) were prepared on the buccal and the lingual surfaces of each tooth. The test groups were: high-speed cavity preparation with diamond rotary cutting instruments (n = 20) and ultrasonic cavity preparation with CVD points (n = 20). During cavity preparation, the increases In pulpal temperature, and the time required for the preparation, were recorded and analyzed by Student's t test for paired samples (alpha = .05).Results. The average pulpal temperature increases were 4.3 degrees C for the high-speed preparation and 3.8 degrees C for the ultrasonic preparation, which were statistically similar (P = .052). However, significant differences were found (P < .001) for the time expended (3.3 minutes for the high-speed bur and 13.77 minutes for the ultrasound device).Conclusions. The intrapulpal temperatures produced during cavity preparation by ultrasonic tips versus high-speed bur preparation were similar. However, the use of the ultrasonic device required 4 times longer for the completion of a cavity preparation.

Roughness of Human Enamel Surface Submitted to Different Prophylaxis Methods

The purpose of this in vitro study was to evaluate alterations in the surface roughness and micromorphology of human enamel submitted to three prophylaxis methods. Sixty-nine caries-free molars with exposed labial surfaces were divided into three groups. Group I was treated with a rotary instrument set at a low speed, rubber clip and a mixture of water and pumice; group II with a rotary instrument set at a low speed, rubber cup and prophylaxis paste Herjos-F (Vigodent S/A Industria e Comercio, Rio de Janeiro, Brazil); and group III with sodium bicarbonate spray Profi II Ceramic (Dabi A dante Indtistrias Medico Odontologicas Ltda, Ribeirao Preto, Brazil). All procedures were performed by the same operator for 10 s, and samples were rinsed and stored in distilled water. Pre and post-treatment surface evaluation was completed using a surface profilometer (Perthometer S8P Marh, Perthen, Germany) in 54 samples. In addition, the other samples were coated with gold and examined in a scanning electron microscope (SEM). The results of this study were statistically analyzed with the paired t-test (Student), the Kruskal-Wallis test and the Dunn (5%) test. The sodium bicarbonate spray led to significantly rougher surfaces than the pumice paste. The use of prophylaxis paste showed no statistically significant difference when compared with the other methods. Based on SEM analysis, the sodium bicarbonate spray presented an irregular surface with granular material and erosions. Based on this study, it can be concluded that there was an increased enamel stuface roughness when teeth were treated with sodium bicarbonate spray when compared with teeth treated with pumice paste.

Simultaneous and Direct Determination of As, Bi, Pb, Sb, and Se and Co, Cr, Cu, Fe, and Mn in Milk by Electrothermal Atomic Absorption Spectrometry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Simultaneous determination of Cu and Pb in fuel ethanol by graphite furnace AAS using tungsten permanent modifier with co-injection of Ir

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of Ir and Pd(NO3)(2)/Mg(NO3)(2) as Modifiers for the Simultaneous Determination of Mn, Ni, Pb, and Sb in Fuel Ethanol by Graphite Furnace MS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influência de nitrato de paládio, nitrato de magnésio e nitrato de níquel no comportamento térmico de arsênio em açúcares por espectrometria de absorção atômica em forno de grafite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sistemas de preparo e resistência à penetração e densidade de um Latossolo Vermelho eutrófico em cultivo intensivo e pousio

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeitos de sistemas de preparo do solo na cultura da soja (Glycine max (L.) Merrill)

Com o objetivo de avaliar o efeito de cinco equipamentos de preparo do solo sobre o desenvolvimento e a produtividade da cultura da soja (Glycine max L. (Merril)), foi conduzida uma pesquisa em Latossolo Vermelho distrófico, no município de Uberaba-MG, em delineamento experimental em blocos casualizados, com cinco tratamentos (escarificador, enxada-rotativa, arado de aivecas, arado de discos e grade aradora) e quatro repetições. Os sistemas de preparo do solo não mostraram diferenças para o número médio de dias para a emergência das plântulas, estande final, altura da primeira vagem e produtividade da cultura da soja. Os tratamentos com arado de disco, arado de aivecas e grade aradora proporcionaram as maiores populações iniciais da cultura. A altura das plantas foi afetada pelos sistemas de preparo utilizados, destacando-se o preparo com o arado de aivecas e com a enxada-rotativa, com os maiores e menores valores absolutos, respectivamente.

Métodos de preparo do solo: alterações na rugosidade do solo

Procurando relacionar os métodos de preparo de solo com alguns dos efeitos em um Latossolo Vermelho distrófico, foi conduzido, no município de Uberaba - MG, um trabalho utilizando-se do delineamento experimental em blocos casualizados, com cinco tratamentos e quatro repetições, tendo como tratamentos os preparos de solo: escarificador, enxada rotativa, arado de aivecas, grade aradora e arado de discos. Foram avaliadas a área mobilizada do solo e a área de elevação, tendo-se como referência a superfície natural do solo antes da mobilização, o empolamento do solo, a espessura média da camada mobilizada, o índice de rugosidade e a modificação da rugosidade do solo para a comparação da rugosidade antes e após sua mobilização. O escarificador proporcionou menor empolamento e maior índice de rugosidade do solo, enquadrando-se como preparo conservacionista por desestruturar menos o solo, podendo colaborar com as menores perdas de solo por erosão.