Wilson Tadeu Felippe

Objetivo: O objetivo deste estudo foi avaliar e comparar a efetividade das soluções de hipoclorito de sódio (NaOCl) 1% e 5%, clorexidina (CHX) 2%, suspensões de nanopartículas de prata (Np Ag) 1% e nanopartículas de óxido de zinco (Np ZnO) 26% contra o biofilme de E. faecalis. Material e Métodos: Setenta e seis dentes humanos unirradiculados foram modelados, montados em um aparato específico e esterilizados. Após, 100 μL de uma suspensão de E. faecalis foi inserida nos canais, sendo renovada diariamente por 7 dias. Quatro segmentos radiculares foram analisados por meio de microscopia eletrônica de varredura (MEV) para confirmar a presença do biofilme. Os segmentos radiculares remanescentes foram divididos aleatoriamente em 6 grupos (n = 12), de acordo com a solução irrigadora empregada: G1) solução salina 0,85% (controle); G2) NaOCl 1%; G3) NaOCl 5%; G4) CHX 2%; G5) suspensão de Np Ag 1%; e G6) suspensão de Np ZnO 26%. Concluída a irrigação, a susceptibilidade do biofilme às soluções irrigadoras (n = 10) foi determinada pelo método de plaqueamento e contagem de unidades formadoras de colônias (UFC). Uma análise por meio de MEV foi conduzida em 2 segmentos de cada grupo para visualização da estrutura do biofilme. O conjunto de dados, representados pelos valores médios de UFC para cada grupo, foi analisado estatisticamente pelos testes Kruskal-Wallis e Mann-Whitney (p < 0,05). Resultados: A efetividade das soluções de NaOCl 5% e Np Ag 1% contra o biofilme intracanal de E. faecalis foi superior comparada à solução salina 0,85% (p < 0,05). NaOCl 5% reduziu 100% das UFC comparado ao grupo controle, seguido pela suspensão de Np Ag 1% (97,6%), Np ZnO 26% (96,1%), NaOCl 1% (94,1%) e CHX 2% (93,1%). Conclusão: Com base na metodologia aplicada, as soluções de NaOCl 5% e Np Ag 1% apresentaram excelente efetividade contra o biofilme de E. faecalis estabelecido no canal radicular. Descritores: Biofilmes. Desinfecção. Enterococcus faecalis. Nanopartículas metálicas.

The aim is to verify, under scanning electron microscopy, the occurrence of apical root resorption in anterior and posterior teeth with chronic and radiographically visible periapical lesions. Thirty‐two teeth were extracted, the apical thirds (n = 39) were removed, and prepared to analyse the external apical root surface. All specimens presented irregular areas of root resorption with different depths, located mainly around the apical foramen. Teeth with chronic periapical lesions present areas of external apical root resorption with irregular surface and different depths located mainly around the apical foramen. Root resorptions may show different configurations and destroy the apical root structure more or less extensively.

To evaluate the capacity of the ROOT ZX II to locate the apical foramen and to control the apical extent of rotary instrumentation. Sixty-five extracted human single rooted teeth were selected and measured directly using a size 15 K-Flexofile introduced in the canal until the tip was visible at the major foramen (direct length, DL). The teeth were then measured electronically (EL1) with the ROOT ZX II when used passively, that is without rotation. To test the auto reverse function, the root canals were instrumented with nickel titanium rotary instruments. Instrumentation was carried out apically until rotation was reversed by the automatic apical reverse (AAR) function at different levels (2, 1 and 0.5). The instrumented length at each level was measured and registered as AAR2, AAR1 and AAR0.5, respectively. After instrumentation, a second passive electronic measurement was conducted and noted as electronic length 2 (EL2). All measurements were expressed in millimetres with accuracy set to 0.5 mm. Percentages of acceptable measurements for each electronic reading were calculated and compared using the proportions test. The Wilcoxon's signed rank test was used to compare the differences between DL/EL1 and DL/EL2, and to compare EL2 with the different AAR measurements. The critical value of statistical significance was 5%. EL1 and EL2 measurements were coincident to DL in 56 (86%) and 54 (83%) of the cases, respectively. The proportions test showed no statistically significant difference between these percentages (P > 0.05). The Wilcoxon's signed rank test did not show any differences (P > 0.05) when comparing the mean difference between DL with EL1 (0.03) and DL with EL2 (0.10). Statistically significant differences were observed when comparing EL2 with AAR2 and with AAR1. The ROOT ZX II reliably located the major apical foramen, but was not an accurate method for controlling the apical extent of rotary instrumentation. Rotary instrumentation with the automatic apical reverse feature was always closer to the foramen than expected.

Aim  To evaluate the influence of mineral trioxide aggregate (MTA) on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals and to verify the necessity of employing calcium hydroxide paste before using MTA.Methodology  Twenty premolars from two 6‐month old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedström files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals of two premolars in each dog were left empty (control group). The other eight teeth in each animal were divided into two experimental groups. The apical thirds of the canals of group 1 were filled with MTA. In the teeth of group 2, the canals were dressed with a calcium hydroxide–propylene glycol paste. After 1 week, the paste was removed and the apical third was filled with MTA. All teeth were restored with reinforced zinc oxide cement (IRM) and amalgam. The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing. The sections were studied to evaluate seven parameters: formation of an apical calcified tissue barrier, level of barrier formation, inflammatory reaction, bone and root resorption, MTA extrusion, and microorganisms. Results of experimental groups were analysed by Wilcoxon's nonparametric tests and by the test of proportions. The critical value of statistical significance was 5%.Results  Significant differences (P < 0.05) were found in relation to the position of barrier formation and MTA extrusion. The barrier was formed in the interior of the canal in 69.2% of roots from MTA group only. In group 2, it was formed beyond the limits of the canal walls in 75% of the roots. MTA extrusion occurred mainly in roots from group 2. There was similarity between the groups for the other parameters.Conclusions  Mineral trioxide aggregate used after root canal preparation favoured the occurrence of the apexification and periapical healing. The initial use of calcium hydroxide paste was not necessary for apexification to occur, and has shown to be strongly related to the extrusion of MTA and formation of barriers beyond the limits of the root canal walls.