: Several strategies have been tried out for the control and antimicrobial treatment of carious lesions such as the direct application of ozone. However, the the oxidation process after the use of ozone facilitates the permanence of residual oxygen, which can negatively influence the use of adhesive systems. The application of 10% sodium ascorbate on the dentin surface can neutralize the effect of oxygen. However, the influence of these substances on the coronary dentin microhardness must be studied. Objective: This study aimed to evaluate the microhardness of human dentin after the application of gaseous ozone and sodium ascorbate. Material and methods: Nineteen third molars were sectioned in order to separate the occlusal surface from the roots leaving a 4 mm thick specimen which was further divided into its mesial and distal parts. The mesial parts were allocated to Group A which was subdivided into two groups: control group, in which the initial microhardness was measured, and an ozone group, in which the application of gaseous ozone was performed for 40 seconds followed by the measurement of the final microhardness. The distal parts were allocated to Group B, subdivided into two groups, a control group in which the initialmicrohardness was measured and an ozone + sodium ascorbate group in which the application of gaseous ozone was performed for 40 seconds and a solution of 10% sodium ascorbate for 10 minutes followed by measurement of the final microhardness. Results: The results showed that there was a statistically significant increase in dentin microhardness (p>0.05) in Group A (control and ozone) and in Group B (control and ozone + sodium ascorbate). However,there was no statistically significant increase in microhardness (p>0.05) between ozone in group A and ozone + sodium ascorbate in group B. Conclusion: The application of gaseous ozone increased the microhardness of human dentin and the application of sodium ascobate had no influence on the microhardness that has already been modified by gaseous ozone.
Purpose:To evaluate the effect of intra-radicular cleaning protocols after post-space preparation (PSP) on marginal adaptation of a luting agent to root dentin. Methods: Eighty bovine incisors were sectioned transversely to obtain 18-mm-long root sections. The roots were prepared with ProTaper instruments and filled using Tagger's hybrid technique. PSP was performed at a length of 14 mm using #3-5 Largo drills. The roots were distributed into eight groups according to the chelating solution used (17% EDTA or 0.2% Chitosan) and the chelating activation/delivery method employed (conventional needle irrigation [CNI], EndoActivator [EA], XP-Endo Finisher [XPF] or passive ultrasonic irrigation [PUI]). The fiber posts were cemented using self-adhesive resin cement, and the roots were sectioned to obtain three discs from each root third. The dentin discs were observed under an optical microscope at ×40 magnification to assess marginal adaptation. The different protocols were compared considering the frequency of the marginal adaptation scores using the Kruskal-Wallis test, followed by the Dwass-Steel-Critchlow-Fligner test (α = 5%). Results: The use of 17% EDTA resulted in better marginal adaptation (P < 0.001). PUI yielded results that were similar to those for EA (P = 0.949) and superior to those for XPF (P = 0.020). The combination of 17% EDTA + PUI provided a greater number of interfaces without marginal gaps (P < 0.001). Conclusion:The cleaning protocol influenced the marginal adaptation of resin cement to root dentin.
Objetivo: Analisar o índice de transporte (IT) e a capacidade de centralização (CC) do preparo do canal radicular com diferentes instrumentos de níquel-titânio por meio da tomografia computadorizada de feixe cônico (TCFC). Material e Métodos: Quarenta e cinco canais mesiovestibulares de molares inferiores prototipados foram aleatoriamente distribuídos em 03 grupos (n=15), conforme o instrumento rotatório empregado: G1. BioRace®; G2. V-File®; G3. Protaper Next®. Imagens de TCFC foram realizadas antes e após o preparo dos canais radiculares. As mensurações foram realizadas por dois examinadores utilizando-se o software OsiriX® DICOM Viewer. Estabeleceu-se o nível de 3 mm abaixo da furca para a realização das mensurações nas imagens. O IT e CC foram analisados conforme metodologia proposta por Gambill et al (1996). Os dados e os valores obtidos foram avaliados pelo teste de Kruskal-Wallis e o nível de significância foi de 5%. Resultados: Todos os instrumentos analisados apresentaram transporte e descentralização. BioRace® e V-File® apresentaram tendência ao transporte para o sentido distal, enquanto o Protaper Next® apresentou tendência para o sentido mesial, porém não foram encontradas diferenças entre os grupos (p>0,05). Não se verificou CC perfeita (=1,0) após o uso dos instrumentos testados. Conclusão: Nenhum instrumento acionado em cinemática de rotação contínua ou reciprocante mostrou ausência de transporte ou capacidade de centralização do canal.
O objetivo deste estudo foi avaliar o surgimento de defeitos na dentina radicular após o uso de diferentes sistemas rotatórios de níquel-titânio (NiTi). Cem molares inferiores humanos tiveram as coroas e raízes mesiais removidas a fim de se obter um espécime de 14 mm da raiz distal. Vinte raízes serviram como controle e não foram preparadas. As demais foram alocadas em 4 grupos (n = 20) e preparadas com os seguintes sistemas: BioRace®, K3®, ProTaper Universal® e Hero 642®. Após o preparo as raízes foram seccionadas perpendicularmente ao seu longo eixo a 1, 3, 6 e 9 mm do ápice, coradas com azul de metileno a 1% e examinadas em um estereomicroscópio com aumento de 40X. Os discos de dentina foram inspecionados e a ausência/presença de defeitos da dentina radicular registrada. A análise estatística dos dados incluiu distribuição de frequência e teste de associação. A significância estatística para a associação entre as variáveis foi determinada pelo teste do Qui-quadrado. O nível de significância estabelecido foi p <0,05. Um total de 300 fatias foram examinadas. O sistema BioRace® promoveu mais fraturas e outros defeitos quando comparado aos sistemas K3® e Hero 642® (p<0,05). Não foram observadas diferenças significativas entre os sistemas BioRace® e ProTaper Universal® (p>0,05). Com relação aos níveis de profundidade do canal radicular, maior quantidade de defeitos foi observada nos cortes realizados a 6 e 9 mm do ápice radicular. O uso de instrumentos de NiTi durante o preparo do canal resultou em defeitos na dentina.
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