Influence of apical enlargement in cleaning and extrusion in canals with mild and moderate curvatures

Optical microscopy and morphometric analysis were used in this study to evaluate, in vitro, the cleaning of the apical region in root canals with mild or moderate curvatures subjected to biomechanical preparation with a rotary system, as well as to assess the amount of extruded material to the periapical area. Lateral incisors (n = 32), 16 with curvature angles smaller or equal to 10º (GI) and 16 between 11º and 25º angles (GII) were submitted to Hero 642 rotary instrumentation with different surgical diameters: (A) 30.02 and (B) 45.02. Irrigation was performed at each change of instrument with 5 mL of ultrapure Milli-Q water and the extruded material through the apical foramen was collected. Root cross-sections were subjected to histological analysis by optical microscopy (×40) and the images were evaluated morphometrically using the Image Tool software. Quantification of the extruded material was performed by weighing after liquid evaporation. ANOVA showed no statistically significant differences (p>0.05) among the groups with respect to the procedures used to clean the apical region. Considering the amount of extruded material, the Tukey's HSD showed that canals with mild curvature prepared with the 45.02 surgical diameter showed significantly higher values (p<0.05) that those of the other groups, which were similar between themselves (p>0.05). In conclusion, the effect of cleaning the apical region did not differ in the groups, considering root curvature and the surgical diameter of instruments used for apical preparation. The amount of extruded material was greater in canals with mild curvature that were prepared with the 45.02 surgical instrument diameter.

Este estudo avaliou, in vitro, por meio de microscopia óptica e morfometria, a limpeza da região apical em canais radiculares com curvatura leve e moderada submetidos ao preparo biomecânico com sistema rotatório, bem como avaliou a quantidade de material extruído para a área apical. Incisivos laterais (n = 32), sendo 16 com ângulo de curvatura igual ou inferior a 10º (GI) e 16 entre 11º e 25º (GII), foram submetidos à instrumentação rotatória com o sistema Hero 642 com diferentes diâmetros cirúrgicos: (A) 30,02 e (B) 45,02. A irrigação, a cada troca de instrumento, foi realizada com água ultra-pura de Milli Q (5 mL), e o material extruído através do forame apical foi coletado. As raízes foram submetidas a análise histológica sob microscopia óptica (40×) e as imagens foram submetidas à análise morfométrica utilizando o software Image Tool. A quantificação do material extruído foi realizada por pesagem, após a evaporação do líquido. A análise de variância não mostrou diferença estatística significante em relação à limpeza da região apical nos diferentes grupos testados (p>0,05). Considerando a quantidade de material extruído, o teste de T6ukey mostrou que os canais com curvatura leve preparados com o diâmetro cirúrgico 45,02 apresentaram os maiores valores, sendo estatisticamente diferente dos demais grupos (p<0,05) que foram semelhantes entre si (p>0,05). Pode-se concluir que a limpeza da região apical não diferiu entre os diferentes grupos, considerando a curvatura radicular e o diâmetro cirúrgico. A quantidade de material extruído foi maior nos canais preparados com curvatura leve que foram preparados com diâmetro cirúrgico 45,02.

Análise histológica dos tecidos periapicais de dentes de cães como recurso para avaliar a influência dos auxiliares químicos da instrumentação no selamento dos canais radiculares obturados com RealSeal® e expostos ao meio bucal / Histological analysis of periapical tissue of dogs´ teeth as a means to evaluate the influence of irrigating solutions in the sealing of root canals filled with RealSeal® and exposed to oral environment

Este estudo, in vivo, visou a avaliar a influência do auxiliar químico no selamento dos canais radiculares obturados com o sistema RealSeal® e preparados para a colocação de pino protético, pela análise da resposta dos tecidos periapicais de dentes de cães. Foram testados os produtos químicos hipoclorito de sódio a 1% e a clorexidina gel a 2%. A pesquisa foi desenvolvida em 6 cães, 10 dentes em cada um deles, num total de 60 dentes e 120 canais divididos em sete grupos, sendo três grupos teste, três grupos controle negativo e um grupo controle positivo. Todos os dentes permaneceram selados por 24 horas após terem sido tratados. Decorrido este prazo, os selamentos provisórios dos dentes pertencentes aos grupos teste e controle positivo foram removidos, permanecendo sem selamento por 90 dias. Os dentes dos grupos controle negativo foram mantidos com selamento durante todo o período experimental, quando os animais foram mortos e suas mandíbulas removidas. O processamento histológico foi realizado com hematoxilina e eosina. A análise histológica, com auxílio de um microscópio óptico, baseou-se na avaliação da situação histológica dos tecidos periapicais. A análise estatística foi realizada a partir do teste não paramétrico de Kruskal-Wallis com localização de diferenças pelos procedimentos de post-hoc, de Mann-Whitney e Willcoxon. O nível de significância considerado adequado foi de 5%. Os grupos experimentais...

The aim of this study was to assess the influence of the cleaning protocol on sealing of root canal obturation with RealSeal following post space preparation, by means of periapical tissue response analysis. 1% sodium hypochlorite and 2% chlorhexidine were the tested products. For this purpose, six dogs were used, 10 teeth in each dog, comprising a total of 60 teeth and 120 root canals, were randomly divided into seven groups, being three test groups, three negative controls and a positive control. Following obturation, all teeth were kept totally sealed during 24 hours to allow sealer setting. Then the positive control and the three test groups had their seal removed, and obturation material exposed to the oral environment for 90 days. Negative controls were kept sealed during the whole experimental period. The animals were killed and their mandibles removed. Histological procedures were adopted as to HE staining. Optical histological analysis at magnifications varying from 25x to 400x considered the periapical tissue status at various sites...

Cleaning ability of chlorhexidine gel and sodium hypochlorite associated or not with EDTA as root canal irrigants: a scanning electron microscopy study

The aim of this study was to evaluate the cleaning efficacy of 2 percent chlorhexidine gluconate gel (CHX) compared to 2.5 percent sodium hypochlorite solution (NaOCl) associated or not with 17 percent EDTA used as irrigants during the biomechanical preparation. Fifty freshly extracted single-rooted human teeth with complete apex formation were randomly divided into five groups: G1 - sterile saline, G2 - 2.5 percent NaOCl, G3 - 2 percent CHX, G4 - 2.5 percent NaOCl + EDTA and G5 - 2 percent CHX + EDTA. The specimens of G1 were subdivided into two control groups. The teeth were decoronated and the coronal and middle root thirds were prepared with Gates-Glidden burs, and the apical third was reserved to manual instrumentation. All procedures were performed by a single operator. In all groups, 2 mL of irrigant was delivered between each file change. The teeth were sectioned and prepared for analyses under scanning electron microscopy (SEM). SEM micrographs were graded according to a score scale by two examiners. Data were analyzed statistically by Kruskal-Wallis and Dunn tests at 1 percent significance level. The best results were obtained in the groups in which the irrigant was used followed by the chelating agent. No statistically significant difference was observed among G4, G5 and the positive control group (p<0.01). The groups G2 and G3 were significantly different from the others, presenting the worst cleaning capacity. In conclusion, the use of the chelating agent is necessary to obtain clean canal walls, with open tubules and no heavy debris. The use of 2 percent chlorhexidine gluconate gel alone is not able to remove the smear layer.