Abstract The survival of endodontically treated teeth depends on the remaining tooth structure. The aim of this study was to evaluate the impact of different access cavities on root canal preparation, restorative protocol, and fracture resistance of endodontically treated teeth. Fifty-six mandibular molars were divided into control (n=8) and experimental (n=16) groups according to access cavity: Traditional, Conservative, and Truss; and redistributed (n=8) according to instrumentation protocols: Reciproc Blue and R-motion. After, teeth were scanned in micro-CT and then filled and redistributed according to composite resin restoration (n=8): Filtek One BulkFill and Filtek Z350. A new micro-CT scan was performed to analyze the restorative material. Then, samples were submitted to fracture resistance testing and the failure pattern was determined. Data were analyzed using paired T-test, ANOVA, Tukey, and chi-square tests (α=0.05). In Truss, R-Motion promoted less transportation in different thirds of root canals. Higher percentages of voids (5.05%) and filling material (11.7%) were observed in Truss. Fracture resistance values were higher for the control group, followed by Truss, Conservative, and Traditional. The predominant failure pattern was type-II. In Truss, reciprocating instruments with smaller taper showed less canal transportation. Also, Truss provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material. Thus, in Truss, reciprocating files with smaller taper showed less canal transportation, and these cavities provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material.

Abstract This study aimed to analyze the root and root canal morphology of mandibular first and second molars using CBCT images. A total of 2,400 mandibular molars exams were selected from 600 patients aged between 18 and 75 years. The number of roots, number of root canals, and root canal configuration according to the Vertucci classification were verified. Overall, 94.92% of mandibular first molars and 90.17% of mandibular second molars had two separate roots. Among the biradicular molars, the first molars showed a greater incidence of type IV canals in the mesial root and type I in the distal root. In the second molars, the most common canal form was type IV in the mesial root and type I in the distal root. In the triradicular molars, the type IV and type I configurations were the most common in the mesial root of the first molar and second molar, respectively. In both triradicular molars, there was a prevalence of type I canal in the distal and DL roots. Statistical analysis was performed at a significance level of 0.05. The number of roots was correlated with gender (Spearman test), and the canal's configuration with gender and bilaterality (Wilcoxon test). The subpopulation studied has a high incidence of bilateral symmetry and mandibular molars with two roots with two distinct mesial canals and one distal canal. The bilateral configuration is possible to estimate the number of canals, especially in images that are difficult to visualize, such as atresic canals.

RESUMO A pesquisa foi realizada com o objetivo de avaliar os diferentes níveis de energia metabolizável (3050, 3100, 3150, 3200 e 3250 kcal.kg-1) na dieta de frango de corte de 22 a 42 dias de idade, mantidos em ambiente de estresse térmico. Trezentos pintos, machos com 814,7 g de peso médio inicial, foram distribuídos em delineamento experimental inteiramente casualizado, com cinco tratamentos, seis repetições e dez aves por unidade experimental. Os níveis de energia metabolizável das rações não influenciaram (P>0,05) as variáveis de desempenho conversão alimentar (CA), ganho diário de peso (GDP) e consumo diário de ração (CDR), nas duas fases estudadas, para as características de carcaça não houve diferenças estatísticas para os rendimentos de: carcaça, peito, coxa, sobrecoxa, coração, asa e dorso, sendo observadas diferenças para as variáveis, rendimento de moela e gordura abdominal. Foi observado aumento linear na porcentagem de gordura abdominal de acordo com o aumento dos níveis de energia na ração. O nível 3100 Kcal.kg-1 de energia metabolizável é o nível indicado nesta pesquisa por apresentar menor teor de gordura abdominal e menor custo por quilo de ração.

ABSTRACT The research was carried out with the objective of evaluating different levels of metabolisable energy (3050, 3100, 3150, 3200 and 3250 kcal.kg-1) in the diet of 22-to-42-day-old broilers kept in an environment of thermal stress. Three hundred male chicks weighing 814.7 g initial average weight were distributed in a completely randomised design with five treatments, six replications and ten birds per experimental unit. Feed metabolisable energy levels did not influence (P > 0.05) the performance variables of feed conversion, daily weight gain and daily feed intake in the two phases studied. There were no statistical differences in carcass yields: carcass, chest, thigh, drumstick, heart, wing and back. Differences were observed for the two variables gizzard yield and abdominal fat. A linear increase in the percentage of abdominal fat with an increase in energy levels in the diet was observed. The 3100 kcal.kg-1 level of metabolisable energy is the level indicated by this research because it results in lower abdominal fat content and lower cost per kilo of feed.

The aim of this study was to evaluate the influence of different restorative procedures on the fracture resistance of endodontically treated teeth submitted to intracoronal bleaching. Fifty upper central incisors were distributed into 5 groups: GI - healthy teeth; GII - endodontically treated teeth sealed with Coltosol; GIII - endodontically treated teeth bleached and sealed with Coltosol; GIV - endodontically treated teeth bleached and restored with composite resin; and GV - endodontically treated teeth bleached and restored with a fiberglass post and composite resin. In the bleached specimens, a cervical seal was made prior to bleaching with 38% hydrogen peroxide. The gel was applied on the buccal surface and in the pulp chamber, and was then light-activated for 45 s. This procedure was repeated three times per session for four sessions, and each group was submitted to the restorative procedures described above. The specimens were submitted to fracture resistance testing in a universal testing machine. There were statistically significant differences among the groups (p < 0.05). The mean value found for GIII was the lowest (0.32 kN) and was significantly different from the values found for GI (0.75 kN), GII (0.67 kN), GIV (0.70 kN), and GV (0.72 kN), which were not significantly different from each other (p > 0.05). The restorative procedures using composite resin were found to successfully restore the fracture resistance of endodontically treated and bleached teeth.

Este estudo avaliou, in vitro, a capacidade de remoção de debris do terço apical de canais radiculares achatados, usando diferentes protocolos de irrigação final. Trinta incisivos centrais mandibulares humanos com a raiz mésio-distal achatada foram preparados usando instrumento rotatório Endo-Flare 25.12 e limas Hero 642 30.06, 35.02, 40.02, irrigadas com 2ml de NaOCl 1% após cada lima. Os espécimes foram aleatoriamente distribuídos em cinco grupos de acordo com a irrigação final dos canais radiculares: Grupo I: 10 mL de água destilada (controle), Grupo II: 10 mL de NaOCl a 1% por 8 min, Grupo III: 2 mL de NaOCl a 1% por 2 min (repetidos 4 vezes), Grupo IV: 10 mL de NaOCl 2,5% por 8 min e Grupo V: 10 mL de NaOCl 2,5% por 2 min (repetido 4 vezes). Os terços apicais dos espécimes foram submetidos a processamento histológico de rotina e cortes transversais com 6 μm de espessura foram obtidos e corados com hematoxilina e eosina. Os espécimes foram analisados em microscopia óptica com aumento final de 40 X e as imagens submetidas à análise morfométrica com a utilização do software Scion Image. A análise de variância evidenciou não haver diferença estatística (p>0,05) entre os grupos GI (2,39 ± 3,59), GII (2,91 ± 2,21), GIII (0,73 ± 1,36), GIV (0,95 ± 0,84) e GV (0,51 ± 0,22). Conclui-se que os protocolos de irrigação final utilizando a seringa Luer apresentaram comportamentos semelhantes na remoção de debris do terço apical de canais radiculares achatados.

This study evaluated in vitro the capacity of debris removal from the apical third of flattened root canals, using different final irrigation protocols. Thirty human mandibular central incisors with a mesiodistal flattened root were prepared using rotary instrumentation by Endo-Flare 25.12 and Hero 642 30.06, 35.02, 40.02 files, irrigated with 2 mL of 1% NaOCl after each file. The specimens were randomly distributed into 5 groups according to the final irrigation of root canals: Group I: 10 mL of distilled water (control), Group II: 10 mL of 1% NaOCl for 8 min, Group III: 2 mL of 1% NaOCl for 2 min (repeated 4 times), Group IV: 10 mL of 2.5% NaOCl for 8 min, and Group V: 10 mL of 2.5% NaOCl for 2 min (repeated 4 times). The apical thirds of the specimens were subjected to histological processing and 6-μm cross-sections were obtained and stained with hematoxylin-eosin. The specimens were examined under optical microscopy at ×40 magnification and the images were subjected to morphometric analysis using the Scion image-analysis software. The total area of root canal and the area with debris were measured in square millimeters. Analysis of variance showed no statistically significant difference (p>0.05) among the groups GI (2.39 ± 3.59), GII (2.91 ± 2.21), GIII (0.73 ± 1.36), GIV (0.95 ± 0.84) and GV (0.51 ± 0.22). In conclusion, the final irrigation protocols evaluated in this study using the Luer syringe presented similar performance in the removal of debris from the apical third of flattened root canals.

OBJETIVOS: Avaliou-se a infiltração marginal apical em caninos superiores, obturados com quatro tipos diferentes de cimento, os quais foram imersos em tinta nanquim e mantidos a uma temperatura de 37º C por 96 horas, descalcificados em solução de ácido clorídrico a 5%, desidratados em série crescente de álcoois e diafanizados em salicilato de metila. MÉTODOS: Para isto, 64 dentes de estoque foram instrumentados pela técnica "crown-down", irrigados com solução de hipoclorito de sódio a 0,5% e divididos em dois grupos experimentais. Os dentes do Grupo I foram subdivididos em quatro sub-grupos de oito elementos e obturados cada um deles com os cimentos Endofill®, N-Rickert®, Sealapex® e Sealer 26®. Os dentes do Grupo II receberam aplicação adicional de laser Er:YAG, tendo seus canais radiculares obturados como aqueles do grupo I. RESULTADOS: A infiltração marginal apical apresentou valores estatisticamente maiores e significantes (p < 0,01), nos dentes obturados com o cimento Endofill®, em relação à infiltração ocorrida nos dentes obturados com os cimentos N-Rickert®, Sealapex® e Sealer 26®. Não houve diferença estatística significante (p > 0,05), quanto à infiltração marginal apical, nos dentes do Grupo I, preparados somente com a solução de hipoclorito de sódio a 0,5%, e naqueles do Grupo II, que foram irradiados com laser Er: YAG. CONCLUSÕES: A irradiação de laser Er:YAG aplicada nas paredes do canal radicular não foi capaz de prevenir a infiltração marginal apical.

OBJECTIVES: The aim of this study was to determine the effect of Er:YAG laser irradiation used to clean dentinal walls on the apical sealing of root canals filled with different types of sealers. Background Data: Laser application to the dentinal walls removed debris, rendering the root canals free of smear layers and leaving the dentinal canaliculi open. METHODS: Sixty-four maxillary canines obtained from laboratory files were instrumented with K-files (Dentsply, Maillefer, Ballaigues, Switzerland) using the crown-down technique, and irrigated with a 0.5% sodium hypochlorite solution. The specimens were divided into two groups of 32 teeth each. In group I, the teeth were instrumented and irrigated with sodium hypochlorite solution, and divided into four subgroups to be sealed with the different materials (Endofill, N-Rickert, Sealapex and Sealer 26). In group II, the root canals were subjected to Er:YAG laser irradiation (200 mJ, 7 Hz and 60 J total energy), followed by root canal sealing as in group I. RESULTS: The data showed lower levels of apical microleakage in the teeth filled with N-Rickert, Sealapex and Sealer 26 cements than in those sealed with Endofill (p < 0.01). No significant difference in microleakage was observed between teeth irrigated only with 0.5% sodium hypochlorite and those submitted to Er:YAG laser application (p > 0.05). CONCLUSIONS: The Er:YAG laser irradiation applied to the root canal walls was not able to prevent apical microleakage.

No presente estudo avaliou-se, in vitro, a influência do cimento endodôntico à base de óxido de zinco e eugenol (EndoFill) na adesão de pinos intra-radiculares cimentados com cimento resinoso (Enforce) ou cimento fosfato de zinco. Vinte e quatro caninos superiores uniradiculares foram distribuídos em dois grupos e obturados com cimento a base de oxido de zinco e eugenol + cones de guta-percha ou somente cones de guta-percha (sem cimento). Em metade dos espécimes em cada grupo (n=6), os pinos intra-radiculares foram cimentados com cimento resinoso Enforce e na outra metade com cimento de fosfato de zinco. Os espécimes foram submetidos a ensaios de resistência à tração numa máquina Instron 4444, sendo os valores de força máxima necessária ao desprendimento dos retentores registrados e submetidos à análise estatística pelo teste de Kruskal-Wallis (p<0,01). Os pinos cimentos com cimento fosfato de zinco apresentaram valor médio de resistência à tração superior (353,4 N) ao dos pinos cimentados com Enforce (134,9 N). Em relação à influência do cimento à base de eugenol na retenção dos pinos intra-radiculares, houve diferença significante (p<0,01) somente entre os grupos cimentados com Enforce, sendo que nos canais obturados com EndoFill + guta-percha houve menor resistência à tração que nos canais obturados apenas com guta-percha (respectivamente 101,5 e 168,2 N). Conclui-se que o cimento à base de fosfato de zinco apresentou maior retenção que o cimento resinoso Enforce e que o cimento obturador contendo eugenol (EndoFill) somente afetou as propriedades adesivas do cimento resinoso.

The present study evaluated, in vitro, the influence of an eugenol-based endodontic sealer (EndoFill) on the adhesion of intra-radicular posts cemented with a resin-based cement (Enforce) ou a zinc phosphate cement. Twenty-four single-rooted maxillary canines were divided into 2 groups (n=12) and obturated with either gutta-percha points plus EndoFill or gutta-percha points alone (no cement). In each group, half of intracanal posts (n=6) were cemented with Enforce resin-based cement and half with zinc phosphate cement. Specimens were submitted to pull-out test in an Instron machine and tensile force was applied at a crosshead speed of 0.5 mm/min until post dislodgement. The maximum forces required for post removal was recorded (N) and means were submitted to statistical analysis by Kruskal-Wallis test (p<0.01). Posts cemented with zinc phosphate cement were significantly more retentive (353.4 N) than those cemented with Enforce (134.9 N) (p<0.01). Regarding the influence of the eugenol-based cement (EndoFill) on post retention, there was statistically significant difference (p<0.01) only between the groups cemented with Enforce, i.e., in the canals filled with EndoFill + guta-percha there was lower bond strength than in the canals filled with gutta-percha points alone (101.5 and 168.2 N, respectively). In conclusion, the zinc-phosphate-based cement showed greater post retention than the resin-based cement. The findings of this study suggest that the eugenol-containing sealer interfered with the adhesive properties of the resin-based cement.

Este estudo in vitro comparou a resistência à remoção por tração de núcleos metálicos fundidos em liga de Cu-Al (Goldent-LA) cilíndricos, jateados, de comprimento constante igual a 9 mm, cimentados com cimento de fosfato de zinco e com três diferentes diâmetros: 0,9 mm, 1,3 mm e 1,7 mm. Trinta e seis caninos superiores hígidos tiveram suas coroas seccionadas, sendo as raízes incluídas em blocos de resina acrílica, e os canais, tratados endodonticamente. Os dentes foram divididos em três grupos para serem preparados e padronizados com o auxílio de um paralelômetro com as seguintes brocas: Grupo 1 - Largo nº 2; Grupo 2 - Largo nº 4; Grupo 3 - Largo nº 6. Os núcleos foram moldados com resina acrílica ativada quimicamente e, após a fundição, foram jateados e tiveram as suas dimensões conferidas com um paquímetro digital. Após a cimentação, os corpos-de-prova foram armazenados em água destilada durante 7 dias, em estufa a 37ºC e, posteriormente, submetidos a teste de tração em uma máquina universal de ensaios Instron 4444. Com a análise estatística dos resultados, pôde-se concluir que não houve diferença estatisticamente significante entre os grupos testados. A variação do diâmetro em núcleos cilíndricos jateados cimentados com fosfato de zinco não afetou a resistência à remoção.

This study compared the resistance to removal by traction of abraded cylindrical metal cast posts of Cu-Al (Goldent-LA). The posts had constant length (9 mm) and three different diameters (0.9, 1.3 and 1.7 mm), and were cemented with zinc phosphate cement. The crowns of 36 sound maxillary canines were sectioned, the roots were immersed in resin blocks and the root canals were endodontically treated. The teeth were divided into three groups to be prepared and standardized with the use of a parallelometer with the following burs: Group 1 - Largo n. 2; Group 2 - Largo n. 4; Group 3 - Largo n. 6. The posts were molded with chemically activated resin and after casting they were abraded and their dimensions were confirmed with a digital caliper. After cementation of the posts in the prepared root canals, the samples were kept at 37ºC in distilled water for 7 days and subsequently submitted to the traction test in a universal testing machine (Instron 4444). The results showed no statistical difference between the groups. Diameter variation (0.9 mm, 1.3 mm and 1.7 mm) in abraded cylindrical posts cemented with zinc phosphate did not affect resistance to removal.

A eficiência de três desinfetantes usados em Odontologia foi estudada na descontaminação de 60 cones de guta-percha contaminados com culturas puras e padronizadas de cinco cepas de microrganismos (Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, Candida albicans ATCC CBS-ICB/USP 562, Bacillus subtilis em esporos ATCC 6633 e Streptococcus mutans ATCC 25175). Os cones foram tratados com solução aquosa de polivinilpirrolidona-iodo 10% (PVP-I; Grupos 1 e 2), solução aquosa de hipoclorito de sódio 5,25% (Grupos 3 e 4) e pastilhas de formaldeído (Grupo 5). Nossos resultados indicam que todos os agentes químicos foram eficientes para a esterilização a frio dos cones de guta-percha em curtos espaços de tempo.

This study evaluated the effectiveness of three disinfectants used in Dentistry for decontamination of gutta-percha cones. Sixty gutta-percha cones were contaminated with standardized pure cultures of five species of microorganisms (Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, Candida albicans ATCC CBS-ICB/USP 562, Bacillus subtilis spores ATCC 6633 and Streptococcus mutans ATCC 25175). The cones were treated with 10% polyvinylpyrrolidone-iodine aqueous solution (PVP-I; Groups 1 and 2), 5.25% aqueous sodium hypochlorite (Groups 3 and 4) and paraformaldehyde tablets (Group 5). All chemical agents were efficient for the cold sterilization of gutta-percha cones in short time periods.