Clinical implementation of comprehending dentin on a microscopic level

SUMMARY: The aim of the present in vitro study is to visualize dentin to get an in-depth knowledge of the nature of dentin that could provide useful information regarding conditioning dentinal substrate when treating dentinal lesions. Forty-nine extracted human third molars were obtained and prepared to produce artificial dentinal lesions through demineralizing with acetic acid for 7 and 14 days, or lactic acid for 7 days. The teeth were divided into groups and treated with either NaOCl, pepsin, trypsin, or phosphoric acid. To obtain information on the morphology of the treated dentinal surfaces, all samples were visualized under high resolution field emission scanning electron microscope. With high magnification reaching x50000 dentin was clearly visualized together with its constitutes. The effect of various demineralization approaches and various treatment protocols were demonstrated clearly. The relationship between the conditioning procedure steps and the subsequent bond strength was discussed. To our best knowledge, there is no previous clear highly magnified scanning electron microscope images for dentin, and dentinal components and constitutes with and without various treatments. The current in vitro study suggests the complexity nature of dentin as a substrate that should be treated carefully especially with technique sensitive procedures such as adhesive restorations.

El objetivo del presente estudio in vitro fue visualizar la dentina para obtener un conocimiento completo de la naturaleza de ella lo que podría proporcionar información útil sobre el acondicionamiento del sustrato dentinario en el tratamiento de lesiones dentinarias. Se obtuvieron 49 terceros molares humanos extraídos y se prepararon para producir lesiones dentinales artificiales mediante desmineralización con ácido acético por 7 y 14 días, o ácido láctico por 7 días. Los dientes se dividieron en grupos y se trataron con NaOCl, pepsina, tripsina o ácido fosfórico. Para obtener información sobre la morfología de las superficies dentinarias tratadas, todas las muestras se visualizaron bajo un microscopio electrónico de barrido de emisión de campo de alta resolución. Con un gran aumento que alcanzó x50000, la dentina se visualizó claramente junto con sus componentes. Se demostró el efecto de varios enfoques de desmineralización y varios protocolos de tratamiento. Se discutió la relación entre los pasos del procedimiento de acondicionamiento y la subsiguiente fuerza de unión. Hasta donde sabemos, no hay imágenes claras previas de microscopio electrónico de barrido altamente ampliadas para la dentina y los componentes y constituyentes de la dentina con y sin diferentes tratamientos. El estudio in vitro actual sugiere la naturaleza compleja de la dentina como sustrato que debe tratarse con cuidado, especialmente en los procedimientos sensibles a la técnica, tal como las restauraciones adhesivas.

The penetration effect of ultrasound and Er:YAG laser irrigation activation techniques on dentine of infected human root canals / 口腔疾病防治

Objective@#This ex vivo study evaluated the effect of ultrasound and Er:YAG laser irrigation activation techniques on the penetration of sodium hypochlorite solution into infected human root canal dentin, providing a reference for clinical infection control of infected root canals.@*Methods @#Thirty-six cases of infected root canals were collected and randomly divided into three groups according to the irrigation technique: 12 cases in the conventional syringe irrigation (CSI) group, 12 cases in the passive ultrasonic irrigation (PUI) group, 12 cases in the Er:YAG laser and photon-induced photoacoustic streaming (PIPS) group and 36 cases of clean root canals (12 cases in the CSI group, 12 cases in the PUI group, 12 cases in the PIPS group). All of the selected root canals were straight root canals of posterior teeth. After standardizing the root length, all canals were subjected to instrumentation and dynamic irrigation. 2% methylene blue solution was used to visualize the penetration of the irrigant. EXAKT cutting and grinding equipment was used to take transverse sections of 100-150 μm at the coronal, middle and apical thirds of the root canals. The data (maximum penetration depth, average penetration depth, and penetration percentage) were observed under a light microscope to evaluate the effect of dye penetration. @*Results @# With the three irrigation techniques, the maximum penetration depth, average penetration depth and penetration percentage of the infected root canals were significantly lower than those of clean root canals in the full length of the root canal (P<0.05). The penetration percentage, average penetration depth and maximum penetration depth of the PIPS group were significantly higher than those of the CSI group in the coronal, middle and apical thirds of the infected root canal, respectively (P<0.05). There was no significant difference in the maximum penetration depth, average penetration depth or penetration percentage between the PUI and CSI groups (P>0.05). There was also no significant difference in the maximum penetration depth, average penetration depth or penetration percentage between the PIPS and PUI groups (P>0.05). @*Conclusion @# The dentine permeability of infected root canals was weaker than that of clean root canals. Er:YAG laser-assisted irrigation activation technology could significantly improve the penetration of sodium hypochlorite solution into infected dentin, but passive ultrasonic irrigation did not significantly improve the penetration.

Human pulp tissue dissolution ability of different extracts of Sapindus mukorossi: An in vitro study / 中草药·英文版

Objective: Due to the many negative properties of sodium hypochlorite used in current root canal treatment, interest in biocompatible natural agents is increasing day by day. The aim of this study was to evaluate whether various extract solutions of Sapindus mukorossi have dissolution effects on human pulp tissues. Methods: Primarily powder extracts were obtained by extracting fruit shells of S. mukorossi in different solvents (ethanol, methanol, buthanol and distilled water). The test solutions were prepared and randomly separated into six groups with 10 samples in each group: ethanol extract, methanol extract, butanol extract, distilled water extract of S. mukorossi, sodium hypochlorite (NaOCl) and the control group. Among these, S. mukorossi extracts were separated into two subgroups, depending on their concentration level (50 µg/mL and 100 µg/mL). The pulp tissues of freshly extracted human molars were used for dissolution test. The weights of the pulpal tissues were measured and recorded for two times after the samples were placed in the solutions. Statistical analysis for all descriptive statistics was performed using SPSS 22 (P < 0.05). Results: Our results showed that maximum percent yield of preparation was obtained in methanol extract of S. mukorossi. Among all of the groups, the best dissolution capacity was seen in the NaOCl group (positive control group). Among S. mukorossi groups, the best tissue solvent solution was found in SMM group at 50 µg/mL and SMB group at 100 µg/mL. Conclusion: The different extracts of S. mukorossi had a capacity to dissolve pulp tissue but this capacity was less than NaOCl. Therefore, further studies will enable the creation of a commercial solution for clinical use by increasing the effectiveness of S. mukorossi while combining it with other endodontic irrigation solutions.

Volume and/or time of naocl influences the fracture strength of endodontically treated bovine teeth

Abstract The aim of this study was to evaluate whether amplifying the volume and/or time of contact of NaOCl affects the fracture strength of endodontically treated bovine teeth. Four bovine incisors from 10 animals were allocated into 4 groups using a split-mouth design. Root canals were instrumented using a sequence of 4 manual stainless steel files and irrigated with a 5.25% alkalized NaOCl solution. The total volume and time of irrigation, per sample, varied among the groups as following: standard volume and time of contact - 15 mL/11.5 min; volume raise - 30 mL/11.5 min; time of contact raise - 15 mL/19 min; and volume and time of contact raise - 30 mL/19 min. Samples were subjected to a fracture resistance assay. At p=0.05, two-way ANOVA statistically scrutinized the results. Effect size of NaOCl time of contact and volume were also calculated (η2). The variation in time (p=0.000), volume of irrigation (p=0.000) and the combination of both (p=0.038) negatively influenced the fracture resistance. Standard volume and time of irrigation showed the highest fracture strength while isolated increase in volume or time reduced in 25% and 37%, respectively, the fracture resistance; the simultaneous increase in volume and time of irrigation promoted a reduction of 47%. Effect size of NaOCl time of contact was superior (0.746) than the volume (0.564). Raising the volume and/or time of a 5.25% alkalized NaOCl solution reduces the fracture resistance of endodontically treated bovine teeth.

Resumo O objetivo desse estudo foi o de avaliar se o aumento de volume e/ou tempo de contato do NaOCl afeta a resistência à fratura de dentes bovinos tratados endodonticamente. Quatro incisivos bovinos de 10 animais foram alocados em 4 grupos usando um desenho experimental de boca dividida. Os canais radiculares foram instrumentados usando uma sequência de 4 limas manuais de aço inoxidável e irrigados com uma solução de NaOCl alcalinizada a 5,25%. O volume total e o tempo de irrigação, por amostra, variaram entre os grupos da seguinte forma: volume e tempo de contato padrão (grupo controle) - 15 mL/11,5 min; aumento de volume - 30 mL/11,5 min; aumento no tempo de contato - 15 mL/19 min; e aumento no volume e no tempo de contato - 30 mL/19 min. As amostras foram submetidas a um ensaio de resistência à fratura. Com p=0.05, o teste two-way ANOVA analisou estatisticamente os resultados. O tamanho do efeito do tempo de contato e volume de NaOCl também foi calculado (h2). A variação no tempo (p=0,000), no volume de irrigação (p=0,000) e a interação entre ambos (p=0.038) influenciaram negativamente a resistência à fratura. O volume e o tempo padrão de irrigação apresentaram a maior resistência à fratura, enquanto o aumento isolado no volume ou no tempo de contato reduziram 25% e 37%, respectivamente, a resistência à fratura; o aumento simultâneo do volume e tempo de irrigação promoveu uma redução de 47%. O tamanho do efeito do tempo de contato com o NaOCl foi superior (0,746) ao volume (0,564). Aumentando o volume e/ou o tempo de uma solução de NaOCl alcalinizada a 5,25% reduz a resistência à fratura de dentes bovinos tratados endodonticamente.

Resistencia al cizallamiento utilizando adhesivo de grabado total y autograbante con y sin hipoclorito de sodio en dentina / Shear strength using total and self etching adhesive with and without sodium hypochlorite in dentin

Es un estudio de investigación cuantitativo donde el objetivo fue determinar la resistencia al cizallamiento utilizando adhesivo de grabado total y autograbante, introduciendo la desproteinización con NaOCl al 5.25 por ciento en dentina y comparar sus valores de resistencia. El estudio se realizó en 31 molares seccionados mesiodistalmente y vestibulo lingual, obteniendo 124 especímenes, se suspendieron en acrílico, pulieron y colocaron en refrigeración a 36 oC durante 48 horas; fueron clasificados en grupos A: Prime & Bond NT, B: NaOCl + Prime & Bond NT, C: NaOCl + Xeno® IV y D: Xeno® IV; se fotoactivó un cilindro de resina compuesta ESTHET-X HD de Dentsply, se mantuvo por 24 horas en horno Felisa con 100 por ciento de humedad, finalmente se probaron en la máquina INSTRON a una velocidad de 1 m/min. Se obtuvieron los siguientes promedios, grupos: A: 6.26, B: 7.71, C: 12.03 y D: 15.06 MPa. Para el grupo C y D que pertenecen al grupo autograbante, fueron estadísticamente significativos para el sustrato dentinal. NaOCl no mostró significancia entre los grupos.

It is a quantitative research where the objective was to determinethe shear strength using total and self etching adhesive, introducing de proteinization with 5.25% NaOCl in dentin and comparing its resistance values. The study was performed on 31 mesiodistally andbuccololingual sectioned molars, obtaining 124 specimens, suspended in acrylic, polished and placed in refrigeration at 36 oC for 48 hours;Were classified into groups A: Prime & Bond NT, B: NaOCl + Prime& Bond NT, C: NaOCl + Xeno® IV and D: Xeno® IV; A: DentsplyESTHET-X HD composite resin cylinder was photoactivated, kept for24 hours in a Felisa oven with 100% humidity, finally tested on theINSTRON machine at a speed of 1 mm/min. The following averageswere obtained, groups: A: 6.26, B: 7.71, C: 12.03 and D: 15.06 MPa.For group C and D belonging to the self-etching group, they werestatistically significant for the dentinal substrate. NaOCl, showed nosignificance between the groups.

Comparative Evaluation Of Anti – Bacterial Efficacy Of Sodium Hypochlorite And Carbolic Acid Against Enterococcus Faecalis As Root Canal Irrigant.

Background: Elimination of microorganisms from infected root canal is a complicated & difficult task. Elimination or sufficient reduction of irritants, microorganisms and prevention of recontamination of the root canal after the treatment is the essential factor for successes of the treatment. Methods: Following materials required for this study i.e. 36 teeth prepared for root canal inoculation, Enterococcus faecalis strain, 5 % and 10 % carbolic acid solution, 5.25 % sodium hypochlorite solution, phosphate buffer saline and normal saline solution. An overnight subculture plate of E.faecalis was taken for inoculum preparation and uniform suspension made in normal saline (02 ml) by taking up isolated colonies and adjusted to 0.5 McFarland standard which gives 1.5 X 108 cfu / ml. Result and Conclusion: From this study, we can conclude that 5.25 % NaOCl is one of the superior and successful endodontic irrigant against 5 % and 10% carbolic acid.In our study, result shows that sodium hypochlorite solution is superior to carbolic acid solution. However, as this study is in vitro study, not simulate the oral environment; further few clinical studies are required in evaluation of antimicrobial efficacy of these solutions for predictable and successful endodontic outcome.

Comparative Evaluation of Smear Layer Removal Efficacy Using QMix 2in1, Chitosan, Smear Clear and Glyde.

Aim and Objective: The effects of four endodontic irrigants and on a smear layer created by hand and rotary instrumentation were evaluated in vitro in the middle and apical thirds of root canals. Materials and Methods: Forty eight mature extracted mandibular premolar teeth with a single root canal and a closed apex were distributed randomly into four groups of 12 teeth each. Whilst cleaning and shaping up to size F5 using Protaper Universal System, the root canals were irrigated with 3 mL of 5.25% NaOCl, between each file size. Group 1 (G1) were irrigated with a final flush of QMix 2in1. The teeth in group 2 (G2) were irrigated with a final flush of 0.2%Chitosan, group 3 (G3) with Smear Clear and group 4 (G4) with Glyde. The teeth were split longitudinally and prepared for examination by scanning electron microscopy. Results: Specimens irrigated with a final flush of Glyde (G4) or 0.2%Chitosan (G2) were cleaner than with QMix and Smear Clear, showing very clean root canal surfaces in the middle one-third but in the apical one-third the smear layer was not completely removed, especially at the openings of the dentinal tubules. Statistical analysis showed no significant difference in the cleanliness of root canal wall between G1, G2, G3 and G4. Conclusion: Irrigation with QMix 2in1, Smear Clear, 0.2%Chitosan, and Glyde and 6% did not remove all the smear layer from the root canal system. All these irrigants showed less effectiveness in removal of smear layer from apical 3rd. Glyde showed maximum efficacy in removal of removal of smear layer followed by 0.2%Chitosan, Smear Clear and then QMix 2in1.

Decontaminant solution on in vitro growth of Byrsonima intermedia seedlings / Solução desinfestante no crescimento in vitro de plântulas de Byrsonima intermedia

Byrsonima intermedia A. Juss. é uma planta medicinal e frutífera do Cerrado, cuja propagação convencional é difícil, devido à presença do endocarpo extremamente lignificado. Embora o hipoclorito de sódio (NaOCl) seja amplamente utilizado para a desinfestação superficial, existem poucos relatos de seus efeitos sobre o crescimento do explante. Neste trabalho, o objetivo foi estudar o efeito de diferentes pHs e períodos de exposição de sementes de B. intermedia em uma solução de NaOCl. As sementes foram submetidas a diferentes tempos de exposição (1, 5 e 10 minutos) numa solução de NaOCl com diferentes pHs (5, 7, 10 e 12) e, após o tratamento com hipoclorito de sódio, os embriões foram inoculados em meio WPM com a concentração de 50% de sais sem sacarose, ágar a 0,5% e pH 5,8 e, depois de 75 dias de cultivo, o crescimento das plântulas foi avaliado. A utilização de NaOCl é eficaz na desinfestação de sementes de B. intermedia, independente da variação do pH ou dos períodos de exposição. A porcentagem de plântulas normais, o comprimento da parte aérea e o número de folhas são positivamente afetados pela utilização de solução de NaOCl a pH de 8,5-8,9 ou pelo aumento do período de exposição, enquanto o número de raízes é afetado apenas pelo aumento do período de exposição na solução NaOCl.

Byrsonima intermedia A. Juss., is a medicinal and fruit plant of the Cerrado in which the conventional propagation is difficult due to the presence of extremely lignified endocarps. Although sodium hypochlorite (NaOCl) is widely used in the surface decontamination, there are few reports of its effects on explant growth. The aim of this work was to study the effect of different pH and exposure periods of B. intermedia seeds to a NaOCl solution. Seeds were subjected to different exposure periods (1, 5 and 10 minutes) to a NaOCl solution at different pH (5, 7, 10 and 12) and after treatment with NaOCl, embryos were inoculated in a WPM medium with 50% concentration of salts without sucrose, 0.5% agar and pH 5.8 and after 75 days of culture the growth of seedlings was evaluated. The use of NaOCl is effective in the decontamination of B. intermedia seeds, independent of pH variation and exposure periods and the parameters such as percentage of normal seedlings, shoot length, and number of leaves are positively affected by the use of NaOCl solution at pH 8.5-8.9 and by increasing the exposure period, however, the number of roots is affected only by increasing the exposure period in the NaOCl solution.

Effects of NaOCl on Neuronal Excitability and Intracellular Calcium Concentration in Rat Spinal Substantia Gelatinosa Neurons

Recent studies indicate that reactive oxygen species (ROS) can act as modulators of neuronal activity, and are critically involved in persistent pain primarily through spinal mechanisms. In this study, we investigated the effects of NaOCl, a ROS donor, on neuronal excitability and the intracellular calcium concentration ([Ca2+]i) in spinal substantia gelatinosa (SG) neurons. In current clamp conditions, the application of NaOCl caused a membrane depolarization, which was inhibited by pretreatment with phenyl-N-tert-buthylnitrone (PBN), a ROS scavenger. The NaOCl-induced depolarization was not blocked however by pretreatment with dithiothreitol, a sulfhydryl-reducing agent. Confocal scanning laser microscopy was used to confirm whether NaOCl increases the intracellular ROS level. ROS-induced fluorescence intensity was found to be increased during perfusion of NaOCl after the loading of 2',7'-dichlorofluorescin diacetate (H2DCF-DA). NaOCl-induced depolarization was not blocked by pretreatment with external Ca2+ free solution or by the addition of nifedifine. However, when slices were pretreated with the Ca2+ ATPase inhibitor thapsigargin, NaOCl failed to induce membrane depolarization. In a calcium imaging technique using the Ca2+-sensitive fluorescence dye fura-2, the [Ca2+]i was found to be increased by NaOCl. These results indicate that NaOCl activates the excitability of SG neurons via the modulation of the intracellular calcium concentration, and suggest that ROS induces nociception through a central sensitization.

Carisolv as an endodontic irrigant in deciduous teeth: An SEM study.

Aim: Root canal irrigation plays an important role in the debridement and disinfection of the root canal system. "The purpose of this study was to evaluate the efficacy of Carisolv TM , 1% sodium hypochlorite (NaOCl) gel, and 1% NaOCl solution as root canal irrigants in deciduous anterior teeth." Materials and Methods: Thirty-six extracted deciduous anterior teeth were used. Root canals were flooded with NaOCl solution in Group A, NaOCl gel in Group B and Carisolv TM in Group C and incubated for 30 min. Scanning electron microscope photomicrographs of canal wall debris in the apical, middle and coronal thirds were scored. Results: The results showed that regardless of irrigation regime, canals were consistently cleaner in the coronal and middle thirds than in the apical thirds. NaOCl solution, NaOCl gel, and Carisolv TM had comparable activity at coronal third and middle third of root canals. At the apical third, NaOCl solution cleaned canals better than NaOCl gel and Carisolv TM . Carisolv TM cleaned debris better than NaOCl gel at the apical third. Conclusion: Carisolv TM can be used as an adjunct to root canal preparation.

Effect of inmersion desinfection with 0, 5 percent sodium hypochlorite and 2 percent glutaraldehyde on alginate and silicone: microbiology and SEM study / Efecto de la desinfección en inmersión con 0, 5 por ciento de hipoclorito sódico y glutaraldehído al 2 por ciento sobre alginato y silicona: estudio de la microbiología y SEM

The disinfection of dental impression materials has become an essential topic of universal concern, as it may be the first instance of microbial contamination during dental care. The purpose of this study is twofold: To determine the effectiveness of disinfection with 0.5 percent sodium hypochlorite and 2 percent glutaraldehyde solutions in irreversible hydrocolloid (alginate) and silicone impressions and to analyze the effect of disinfection on surface quality with a scanning electronic microscope. Atotal of 32 impressions (16 made of irreversible hydrocolloid and 16 made of silicone) were taken from maxillary dentate patients. Samples of 1cm2 (80 , irreversible hydrocolloid, 80 silicone) were obtained and distributed in ten groups: alginate in no disinfectant (control group 1, AL), alginate in 0.5 percent sodium hypochlorite (NaOCl) for 5 (AH5) and 10 minutes (AH10), alginate in 2 percent glutaraldehyde for 5 (AG5) and 10 minutes (AG10), silicone in no disinfectant (control group 2), silicone in 0.5 percent NaOCl for5 (SH5) and 10 minutes (SH10), and silicone in 2 percent glutaraldehyde for 5 (SG5) and 10 minutes (SG10). Each sample was divided into two segments (one for the microbiological and one for the SEM study). Microbiological samples were planted on blood agar, Mac Conkey agar, and Sabouraud agar, and identification was made by Gram´s stain. The samples were then processed by an SEM. Immersion in the 5 percent NaOCl and 2 percent glutaraldehyde for 10 minutes completely eliminated bacteria in the impressions, compared with the control group (P=0.000004). Immersion in 0.5 percent NaOCl and 2 percent glutaraldehyde for 5 and 10 minutes significantly inhibited bacterial growth in both the irreversible hydrocolloid and silicone impressions compared with control group (P<0.05). However, in the SEM study, immersion in both disinfectant solutions for 5 and 10 minutes did not significantly affect the surface quality of the irreversible hydrocolloid...

La desinfección de los materiales de impresión dental se ha convertido en un tema esencial, ya que puede ser el primer caso de contaminación microbiana durante la atención dental. El propósito de este estudio es doble: determinar la eficacia de la desinfección con hipoclorito sódico al 0,5 por ciento y 2 por ciento de glutaraldehído en soluciones de hidrocoloide irreversible (alginato) y las impresiones de silicona, para analizar el efecto de la desinfección en la calidad de la superficie con un microscopio electrónico de barrido. Un total de 32 impresiones (16 hechas de hidrocoloides irreversibles y 16 de silicona) superiores de pacientes dentados fueron estudiadas. Las muestras de 1cm2 (80, hidrocoloide irreversible, el 80 de silicona) fueron obtenidas y distribuidas en diez grupos: alginato sin desinfectante (grupo de control1, AL), alginato en el 0,5 por ciento de hipoclorito sódico (NaOCl) durante 5 (AH5) y 10 minutos (AH10), alginato en glutaraldehído al 2 por ciento durante 5 (GA5) y 10 minutos (AG10), silicona sin desinfectante (grupo de control 2), silicona en 0,5 por ciento de NaOCldurante 5 (SH5) y 10 minutos (SH10) y, en glutaraldehído al 2 por ciento durante 5 (SG5) y 10 minutos (SG10). Cada muestra se dividió en dos segmentos (uno para los análisis microbiológicos y uno para el estudio SEM). Las muestras microbiológicasse sembraron en agar sangre, agar MacConkey y agar Sabouraud, y la identificación se realizó por tinción de Gram. Las muestras fueron procesadas por un SEM. La inmersión en 5 por ciento NaOCl y 2 por ciento de glutaraldehído durante 10 minutos eliminó completamente las bacterias de las impresiones, en comparación con el grupo control (P = 0,000004). La inmersión en 0,5 por ciento de NaOCl y glutaraldehído al 2 por ciento durante 5 y 10 minutos, inhibió el crecimiento de bacterias, tanto en el hidrocoloide irreversible e impresiones de silicona en comparación con el grupo control (P <0,05). Sin embargo, en el estudio SEM...

Changes in micro-TBS to pulp chamber dentin after the application of NaOCl & reversal effect by using sodium ascorbate / 대한치과보존학회지

Clinical suggestion for the limitation of application time of NaOCl solution is needed to avoid large reductions in resin-dentin bond strength. The aim of this study was to measure the change of micro-tensile bond strength after the various application time of 5.25% NaOCl solution to pulp chamber dentin in endodontic access cavity, and to evaluate the effect of 10% sodium ascorbate application for 10 min on bond strength after the treatment of 5.25% NaOCl solution. In this experiment, there were no statistical differences(p>0.05) in bond strengths between upper chamber dentin and lower chamber dentin. NaOCl-treated group for 20 min did not show any significant decrease(p>0.05) in bond strength than non-treated control group. In contrast to that, bond strengths of NaOCl-treated groups for 40 & 80 min were significantly lower(p<0.05) than that of non-treated control group. 10% sodium ascorbate retreated group for 10 min after 5.25% NaOCl application for 40 min to chamber dentin showed the recovery of bond strength significantly. However, the bond strength of sodium ascorbate retreated group after 5.25% NaOCl application for 80 min was still significantly lower(p<0.05) compared to the non-treated control group, which means the reductions in resin-dentin bond strength were not fully reversed. On the contrary, sodium ascorbate retreated group after 5.25% NaOCl application for 5 min showed significantly higher(p<0.05) bond strength compared to the control group, which demonstrates its superior recovery effect. In SEM exminations of specimens retreated with 10% sodium ascorbate after NaOCl application for 40 & 80 min showed that resin tags were formed clearly and densely, but weakly in density and homogeneity of individual resin tag compared to the control specimen.

Adhesion of Epiphany and AH Plus sealers to human root dentin treated with different solutions

This study evaluated comparatively the adhesion of Epiphany and AH Plus endodontic sealers to human root dentin treated with 1 percent NaOCl and 1 percent NaOCl+17 percent EDTA, using the push-out test. Sixty root cylinders obtained from maxillary canines had the canals prepared and were randomly assigned to 3 groups (n=20), according to root dentin treatment: GI - distilled water (control), GII - 1 percent NaOCl and GIII - 1 percent NaOCl+17 percent EDTA. Each group was divided into 2 subgroups (n=10) filled with either Epiphany or AH Plus. Bond strength push-out test data (kN) were obtained and analyzed statistically by ANOVA and Tukey's post-hoc test. There was statistically significant difference between sealers (AH Plus: 0.78 ± 0.13; Epiphany: 0.61 ± 0.19; p<0.01) and among root dentin treatments (distilled water: 0.58 ± 0.19; 1 percent NaOCl: 0.71 ± 0.12; 1 percent NaOCl+17 percent EDTA: 0.80 ± 0.17; p<0.05). In conclusion, AH Plus sealer presented greater adhesion to dentin than Epiphany, regardless of the treatment of root canal walls.

O objetivo do presente estudo foi avaliar a adesividade do cimento Epiphany à dentina radicular previamente tratada com hipoclorito de sódio a 1 por cento e EDTA a 17 por cento, em comparação ao cimento AH Plus, pelo método do "push-out". Foram preparados sessenta cilindros de raízes de caninos superiores humanos que foram distribuídos em 3 grupos (n=20) de acordo com o tratamento da dentina: GI água destilada (controle), GII hipoclorito de sódio 1 por cento e GIII EDTA 17 por cento. Esses grupos de corpos-de-prova foram distribuídos em 2 subgrupos para receber os cimentos obturadores a serem testados: Ephiphany e AH Plus. Foi realizado o teste do "push-out" e os resultados (em kN) foram analisados estatisticamente por ANOVA e o teste "post-hoc" de Tukey. A análise demonstrou diferença estatisticamente significativa entre os cimentos (AH Plus: 0,78 ± 0,13; Epiphany: 0,61 ± 0,19; p < 0,01) e entre as soluções testadas (água destilada: 0,58 ± 0,19; NaOCl: 0,71 ± 0,12; EDTA: 0,80 ± 0,17; p<0,05). Conclui-se que o cimento AH Plus apresentou valores de adesividade superiores aos obtidos pelo cimento Epiphany, independente do tratamento realizado nas paredes dos canais radiculares.

Influence of Sodium Ascorbate on Microtensile Bond Strengths to Pulp Chamber Dentin treated with NaOCl / 대한치과보존학회지

The purpose of this study was to evaluate the influence of sodium ascorbate on microtensile bond strengths of total-etching adhesive system to pulp chamber dentin treated with NaOCl. Pulp chambers of extracted human non-caries permanent molars were treated as follows: group 1, with 0.9% NaCl; group 2, with 5.25% NaOCl; group 3, with 5.25% NaOCl and 10% sodium ascorbate for 1min; group 4, with 5.25% NaOCl and 10% sodium ascorbate for 1 min and 10ml of water; group 5, with 5.25% NaOCl and 10% sodium ascorbate for 5 min; group 6, with 5.25% NaOCl and 10% sodium ascorbate for 5 min and 10ml of water; group 7, with 5.25% NaOCl and 10% sodium ascorbate for 10 min; group 8, with 5.25% NaOCl and 10% sodium ascorbate for 10 min and 10ml of water. Treated specimens were dried, bonded with a total-etching adhesive system (Single bond), restored with a composite resin(Z250) and kept for 24h at 100% humidity to measure the microtensile bond strength. NaOCl-treated group (group 2) demonstrated significantly lower strength than the other groups. No significant difference in microtensile bond strengths was found between NaCl-treated group (group 1) and sodium ascorbate-treated groups (group 3-8). The results of this study indicated that dentin treated with NaOCl reduced the microtensile bond strength of Single bond. Application of 10% sodium ascorbate restored the bond strength of Single bond on NaOCl-treated dentin. Application time of sodium ascorbate did not have a significant effect.

Time-dependent effects of EDTA application on removal of smear layer in the root canal system / 대한치과보존학회지

This study was to verify that the combined application of NaOCl and EDTA was more effective in removal of smear layer than the application of NaOCl alone. Furthermore it was aimed to find out the optimal time for the application of EDTA. Thirty five single rooted teeth were cleaned and shaped. NaOCl solution was used as an irrigant during instrumentation. After instrumentation, root canals of the control group were irrigated with 5 ml of NaOCl for 2 minutes. 30 sec, 1 min, and 2 min group were irrigated with 5 ml of 17% EDTA for 30 sec, 1 min, and 2 min respectively. Then the roots were examined with scanning electron microscopy for evaluating removal of smear layer and erosion of dentinal tubule. The results were as follows; 1. The control group: The smear layer was not removed at all. 2. The other groups: 1) Middle(1/3): All groups showed almost no smear layer. And the erosion occurred more frequently as increasing irrigation time. 2) Apical(1/3): The cleaning effect of 2 min group was better than the others. The results suggest that 2 min application of 17% EDTA should be adequate to remove smear layer on both apical(1/3) and middle(1/3).

The effect of smear layer treatment on the microleakage / 대한치과보존학회지

The purpose of this study was to compare the sealing ability of root canal obturation with or without the treatment of smear layer. Eighty extracted human teeth with one canal were selected. Instrumentation was performed with crown-down technique. After instrumentation, root canals of the NaOCl group and NaOCl-6 group were irrigated with 3% NaOCl. EDTA group and EDTA-6 group were irrigated with 17% EDTA. Then all teeth were obturated using continuous wave obturation technique. NaOCl group and EDTA group were immersed in methylene blue solution for 84hours. NaOCl-6 group and EDTA-6 group were immersed in methylene blue solution for 6months. The teeth were sectioned at 1.5 mm (Level 1), 3.0 mm (Level 2) and 4.5 mm (Level 3) from the root apex. The length of dye-penetrated interface and the circumferential length of canal at each level were measured using Sigma-Scan Pro 5.0. 1. The mean leakage ratio was decreased cervically. 2. NaOCl group showed higher mean leakage ratio than EDTA group at each level. But there was significant difference at level 1 only (p < 0.05). 3. NaOCl-6 group showed higher mean leakage ratio than EDTA-6 group at each level. But there was significant difference at level 1 only (p < 0.05). 4. NaOCl-6 group showed higher mean leakage ratio than NaOCl group at each level. But there was significant difference at level 1 only (p < 0.05). 5. EDTA-6 group showed higher mean leakage ratio than EDTA group at each level. But there was no significant difference. 6. In NaOCl group and NaOCl-6 group, scanning electron micrographs of tooth sections generally covered with smear layer. In EDTA group and EDTA-6 group, tooth sections showing the penetration of sealers to opened dentinal tubules. The results suggest that removal of smear layer was effective to reduce the apical microleakage of the root canal.

The effect of NaOCl treatment and sterilization procedures on the corrosion of endodontic files / 대한치과보존학회지

A variety files made of stainless steel (S-S) or nickel-titanium (Ni-Ti) are used during endodontic treatment. The purpose of this study was to evaluate the corrosion susceptibility of S-S and Ni-Ti endodontic files. Three brands of files were used for this study: K-flex(R) S-S files (Maillefer, USA), Profile(R) Ni-Ti files (Maillefer, USA), K-3(R) Ni-Ti files (SybronEndo, USA). 120 files of each brands (21mm, ISO size #20) were divided into 12 groups according to 1) sterilization methods using Autoclave or Ethylene Oxide (E-O) gas, 2) Irrigation solutions using 5.25 % NaOCl or Saline, 3) the number of sterilization (1, 5, 10 times). After above procedures, each of the files was inspected by three examiners with a light microscope and camera at X25. Each file was judged and ranked according to the following criteria: 0; no corrosion, 1; mild corrosion, 2; moderate corrosion, and 3; severe corrosion. The files of high score were examined under the Scanning Electron Microscope. Data were statistically analyzed with the Kruskal-Wallis test (p < 0.05). Most of the ten time-autoclaved files had showed mild to moderate corrosion. But, one or five time-autoclaved files did not show corrosive surface. NaOCl treatment and E-O gas sterilization did not influence on corrosion. There was a significant difference in corrosion susceptibility between sterilization methods and the number of autoclaving. However, there was no significant difference between brands and file materials.