Intracanal Irrigating Solutions Prior to Calcium Hydroxide Medication and Its Effects on Root Dentin Strength

Abstract The aim of this study was to assess the effects of intracanal irrigation with sodium hypochlorite (NaOCl) and ethylenediaminetetracetic acid (EDTA) prior to calcium hydroxide medication on the compressive strength of root dentin. Forty-eight roots with single and straight canals were instrumented with a crown-down technique using Flexofile files and Gates Glidden burs, under 0.9% sodium chloride (NaCl) irrigation. Root canals were randomly separated into 4 groups (n=12), according to the irrigating solution: Control Group, 0.9% NaCl; GroupNaOCl, 1% NaOCl; GroupEDTA, 17% EDTA; and GroupEDTA+NaOCl, 17% EDTA and 1% NaOCl. Solutions remained for 40 min, renewed every 10 min, except for GroupEDTA+NaOCl, where the solutions were alternated every 10 min. Canals were dried and filled with calcium hydroxide paste, and radiographed. Each canal was sealed and stored at 37 °C for 30 days. After this period, the roots were cut 1 mm below the cementoenamel junction and 6 mm apically from this point in order to obtain 6 mm-long cylinders. The compressive test was conducted with a crosshead speed of 1 mm/min. The means (±SD) (MPa) of compressive strength were: Control Group, 151.23±94.36; GroupNaOCl, 167.50±57.25; GroupEDTA, 108.79±99.88; GroupEDTA+NaOCl, 60.12±92.10. Significant statistical differences among groups were found (ANOVA and Tukey, a=5%, p=0.02). Control Group and GroupNaOCl showed higher means of compressive strength than GroupEDTA+NaOCl. Intracanal irrigation with 17% EDTA and 1% NaOCl produced a significant reduction of dentin compressive strength 30 days after medication with calcium hydroxide.

Resumo O objetivo desse estudo foi avaliar o efeito da irrigação intracanal com hipoclorito de sódio (NaOCl) e ácido etilenodiamino tetracético (EDTA) previamente à medicação de hidróxido de cálcio na resistência à compressão da dentina radicular. Quarenta e oito raízes com canais únicos e retos tiveram os canais instrumentados pela técnica coroa-ápice com limas Flexofile e brocas Gates Glidden sob irrigação com solução salina (NaCl) a 0,9%. Os canais radiculares foram separados em 4 grupos (n=12), de acordo com a solução irrigadora: Grupo Controle, NaCl 0,9%; GrupoNaOCl, NaOCl 1%; GrupoEDTA, EDTA 17%; e GrupoEDTA+NaOCl, NaOCl 1% e EDTA 17%. As soluções permaneceram por 40 min, sendo renovadas a cada 10 min, exceto para o GrupoEDTA+NaOCl, onde as soluções foram alternadas a cada 10 min. Os canais foram secos, preenchidos com pasta de hidróxido de cálcio e radiografados. Cada canal foi selado e mantido a 37 °C por 30 dias. Após esse período, as raízes foram cortadas 1 mm abaixo da junção cemento-esmalte e 6 mm apicalmente a este corte, a fim de obter cilindros de 6 mm de comprimento. O teste de compressão foi realizado com velocidade de cruzeta de 1 mm/min. As médias (±SD) da resistência à compressão em MPa foram: Grupo Controle, 151.23±94.36; GrupoNaOCl, 167.50±57.25; GrupoEDTA, 108.79±99.88; GrupoEDTA+NaOCl, 60.12±92.10. Diferenças estatisticamente significativas foram encontradas entre os grupos (ANOVA e Tukey; a=0,05; p=0,02). O Grupo Controle e o GrupoNaOCl obtiveram maiores médias de resistência à compressão em relação ao GrupoEDTA+NaOCl. A irrigação intracanal com EDTA 17% e NaOCl 1% promoveu redução significativa da resistência à compressão da dentina, após 30 dias de medicação intracanal com hidróxido de cálcio.

Adhesion of an endodontic sealer to dentin and gutta-percha: shear and push-out bond strength measurements and SEM analysis

The use of an adequate method for evaluation of the adhesion of root canal filling materials provides more reliable results to allow comparison of the materials and substantiate their clinical choice. The aims of this study were to compare the shear bond strength (SBS) test and push-out test for evaluation of the adhesion of an epoxy-based endodontic sealer (AH Plus) to dentin and gutta-percha, and to assess the failure modes on the debonded surfaces by means of scanning electron microscopy (SEM). Three groups were established (n=7): in group 1, root cylinders obtained from human canines were embedded in acrylic resin and had their canals prepared and filled with sealer; in group 2, longitudinal sections of dentin cylinders were embedded in resin with the canal surface smoothed and turned upwards; in group 3, gutta-percha cylinders were embedded in resin. Polyethylene tubes filled with sealer were positioned on the polished surface of the specimens (groups 2 and 3). The push-out test (group 1) and the SBS test (groups 2 and 3) were performed in an Instron universal testing machine running at crosshead speed of 1 mm/min. Means (±SD) in MPa were: G1 (8.8±1.13), G2 (5.9±1.05) and G3 (3.8±0.55). Statistical analysis by ANOVA and Student's t-test (a=0.05) revealed statistically significant differences (p<0.01) among the groups. SEM analysis showed a predominance of adhesive and mixed failures of AH Plus sealer. The tested surface affected significantly the results with the sealer reaching higher bond strength to dentin than to gutta-percha with the SBS test. The comparison of the employed methodologies showed that the SBS test produced significantly lower bond strength values than the push-out test, was skilful in determining the adhesion of AH Plus sealer to dentin and gutta-percha, and required specimens that could be easily prepared for SEM, presenting as a viable alternative for further experiments.

Análise comparativa ex vivo da eficiência na odontometria de três localizadores apicais eletrônicos: root zx, bingo 1020 e ipex / Comparative analisys ex vivo of the accuracy of three apex locator: root zx, bingo 1020 and ipex

Introdução e Objetivo: O objetivo do presente estudo foi avaliar ex vivo a precisão da leitura de três localizadores apicais eletrônicos: Root ZX, Bingo 1020 e Ipex em relação à medida real dos dentes. Material e métodos: Foram selecionados 50 dentes pré-molares extraídos, unirradiculares. Após abertura coronária, a mensuração do comprimento do dente (CD) foi realizada diretamente pela inserção de uma lima K#10 no canal até que sua ponta fosse observada no forame apical com auxílio de uma lente de aumento (8X). Após a remoção da lima, seu comprimento foi registrado com precisão de 0,01 mm com uso de paquímetro digital. Em seguida, os dentes foram mensurados eletronicamente (CE) com os 3 localizadores apicais até atingir a marca 0 no visor de cada aparelho. As medidas obtidas eletronicamente foram comparadas com o CD e as diferenças analisadas pelo teste de Kruskal-Wallis e pelo teste de proporções (? = 0,05). Resultados: Verificou-se que o sistema Root ZX foi diferente do Ipex (p < 0,01) e o sistema Bingo apresentou resultado intermediário, mostrando-se estatisticamente semelhante aos sistemas Root ZX e Ipex (p > 0,05). Dentro do limite de tolerância de ± 1,0 mm, os resultados demonstraram uma precisão de 100% para o Root ZX, 94% para o Bingo e 90% para o Ipex quando comparados aos valores do CD. Porém, no limite de ± 0,5 mm a precisão obtida foi de 90% para o Root ZX, 68% para o Bingo e de 52% para o Ipex. Conclusão: Todos os dispositivos eletrônicos testados foram hábeis em determinar com precisão o comprimento do dente quando considerada uma variação de 1 mm em relação à posição do forame apical. Porém, quando considerada uma variação de 0,5 mm apenas o aparelho Root ZX mostrou-se preciso.

Introduction and Objective: The objective of this study was to evaluate ex vivo the reading accuracy of three electronic apex locators: Root ZX, Bingo 1020 and Ipex in respect to the real measure of the teeth. Material and methods: Fifty single root premolar teeth extracted were selected. After coronary access, the length tooth (LT) measurement was directly realized by insertion of a K#10 file until its tip was observed in the apical foramen with the help of a magnifying glass (8X). After removing the file, its length was recorded with accuracy of 0.01 mm using digital caliper. Then, the teeth were electronically measured (LE) whit three apex locators until to achieve the zero mark on the display of each unit. The measures electronically obtained were compared with the LT and the differences were analyzed by Kruskal-Wallis Test and Test of proportions (? = 0,05). Results: It was found that the Root ZX system was statistically different from Ipex (p <0.01), the Bingo system presented intermediary result and were statistically similar to the Root ZX and Ipex systems (p> 0.05). Within the limit of tolerance of ± 1.0 mm, the results showed an accuracy of 100% for ZX Root, 94% for Bingo and 90% for Ipex when compared to the LT values. However, in the limits of ± 0.5 mm the accuracy achieved was 90% for Root ZX, 68% for Bingo and 52% for the Ipex. Conclusion: It was concluded that all electronic devices tested were able in determining the precise tooth length when considered a variation of 1 mm from the position of apical foramen. But when considered a variation of 0,5mm only the unit Root ZX proved to be accurate.