Cytotoxicity assessment of 1% peracetic acid, 2,5% sodium hypochlorite and 17% EDTA on FG11 and FG15 human fibroblasts / Avaliação da citotoxicidade de ácido peracético a 1%, hipoclorito de sòdio a 2,5% e EDTA a 17% em fibroblastos humanos FG11 e FG15

The aim of this study was to evaluate the cytotoxic effects of 2.5% sodium hypochlorite (NaOCl), 17% ethylenediamine tetraacetic acid (EDTA), and 1% peracetic acid (PAA) on human fibroblasts. FG11 and FG15 cell lines were cultured in 24well cell culture plates for cell proliferation assessment and 96well cell culture plates for the methylthiazolyldiphenyltetrazolium bromide (MTT) assay; Dulbecco's modified Eagle's medium (DMEM) was used as control data. The experimental solutions were used at 0.01%, 0.05%, and 0.1% dilutions and assessed at 1, 2, and 4hour intervals. Data were subjected to statistical analysis by twoway analysis of variance (ANOVA), followed by the Bonferroni test at a significance level of p <0.05. The assessment of cell proliferation in this study showed cytotoxicity to the fibroblasts with 2.5% NaOCl for all three dilutions at all time intervals, 17% EDTA for the 0.05% and 0.1% dilutions at the 2and 4hour intervals, and 1% PAA for all three dilutions at the 4hour interval. The cell viability assay (MTT assay) for fibroblasts showed 2.5% NaOCl to be cytotoxic at the 0.05% and 0.1% dilutions at all time intervals, 17% EDTA to be cytotoxic at the 0.1% dilution at the 2and 4hour intervals, and 1% PAA to be cytotoxic at the 0.1% dilution at the 2and 4hour intervals. In conclusion, 1% PAA was less cytotoxic than 2.5% NaOCl and 17% EDTA (AU)

O objetivo do presente estudo foi o de avaliar os efeitos citotóxicos de hipoclorito de sódio (NaOCl) a 2,5%, ácido etilenodiaminotetracético (EDTA) a 17% e ácido peracético (PAA) a 1% em fibroblastos humanos. As linhagens celulares FG11 e FG15 foram colonizadas em 24well cell plates para avaliação da proliferação celularr e em 96well cell plates para o ensaio de MTT; O médio modificado Dulbecco's Eagle's (DMEM) foi usado como controle. As soluções experimentais foram usadas com diluições de 0,01%, 0.05%, e 0,1% e avaliadas com 1, 2 e 4 horas de intervalo. Os dados foram submetidos à análise estatística pelo twoway ANOVA, seguido do teste de Bonferroni com nível de significância de p <0.05. A avaliação da proliferação celular neste estudo mostrou o NaOCL a 2,5% como citotóxico nas 3 diluições e 3 intervalos de tempo, o EDTA a 17% nas diluições de 0,05% e 0,1% nos intervalos de 2 e 4 horas, e o PAA a 1% em todas as diluições no intervalo de 4 horas. O teste de viabilidade cellular (MTT) mostrou o NaOCl a 2,5% citotóxico a 0,05% e 0,1% em todos os intervalos, o EDTA a 17% citotóxico nas diluições de 0,1% nos intervalos de 2 e 4 horas e o PAA a 1% citotóxico na diluição de 0,1% nos intervalos de 2 e 4 horas. Como conclusão o PAA a 1% mostrouse menos citotóxico que o NaOCl a 2,5% e o EDTA a 17% (AU)

Effectiveness of the waveone and protaper D systems for removing gutta-percha with or without a solvent / Eficiência dos sistemas waveone e protaper D na remoção de guta-percha com ou sem uso solvente

Endodontic retreatment requires complete removal of the filling material and access to the apical foramen. The purpose of this study was to evaluate the effectiveness of the WaveOne reciprocating system and compare it to the ProTaper D rotary system, with or without the use of a solvent, in removing filling material from root canals. The time required for each filling removal technique employed was also determined and compared. Forty extracted human mandibular premolars with a single, straight, flattened canal were prepared and filled. They were divided into four groups (n = 10): Group 1: ProTaper D NiTi rotary instruments; Group 2: ProTaper D NiTi rotary instruments, with a solvent; Group 3: WaveOne primary instrument; and Group 4: WaveOne primary instrument, with a solvent. The teeth were then split along their long axis and photographed using an operating microscope with 5X magnification. The amount of remaining filling material was assessed with Image Tool software. The results were compared using the KruskalWallis test (p <0.05). There was no significant difference between groups regarding the amount of residual filling material (p > 0.05). Operative time was significantly longer in Group 3 than in groups 1, 2 and 4 (p < 0.05). The WaveOne system and the ProTaper D system were equally effective, with or without a solvent. The time required to remove the filling material from the canals was significantly longer in Group 3 than in the other groups.

No retratamento endodôntico, a completa remoção do material obturador e o acesso ao forame apical são necessários para permitir a limpeza do sistema de canais. O propósito deste estudo foi avaliar a eficácia do sistema reciprocante WaveOne e comparála ao sistema rotatório ProTaper Universal, com ou sem o uso de solvente, na remoção do material obturador.O tempo necessário a cada técnica empregada foi determinado e comparado. Quarenta prémolares inferiores humanos extraídos com canal único, reto e achatado foram preparados e obturados. Foram então divididos em quatro grupos (n = 10) de acordo com o sistema utilizado, como segue. Grupo 1: ProTaper D Niti; Grupo 2: Sistema ProTaper D com solvente; Grupo 3: Sistema WaveOne instrumento Primary; e Grupo 4: Sistema WaveOne instrumento Primary com solvente, sendo o tempo registrado. Os dentes foram clivados longitudinalmente e fotografados utilizando microscópio operatório com aumento de 5 vezes.A quantidade de material remanescente foi avaliada com o uso do software Image Tool 3.0. Os resultados foram comparados utilizando o teste de KruskalWallis( p < 0.05). Em relação aos resultados, não houve diferença significativa entre os grupos quanto à quantidade de material obturador residual (p > 0.05). O tempo operatório no Grupo 3 foi significativa mente maior do que nos grupos 1, 2 e 4 (p < 0.05).O sistema WaveOne foi tão efetivo quanto o ProTaper D, com ou sem solvente.tempo necessário à desobturação dos canais no Grupo 3 (WaveOne sem solvente) foi significativamente maior do que nos demais grupos.

Sealing ability of mineral trioxide aggregate (MTA) combined with distilled water, chlorhexidine, and doxycycline.

The aim of this study was to evaluate the sealing ability of mineral trioxide aggregate (MTA Bio) combined with different mixing agents (distilled water, chlorhexidine, doxycycline), used as an apical root-end filling material. Forty-two extracted human teeth were divided into three groups (n = 12); six teeth were used as controls. Root-ends were resected at 90 degrees, 3 mm from the apex. Root-end cavities were prepared using ultrasonic tips and filled with MTA Bio plus distilled water, 2% chlorhexidine solution, or 10% doxycycline solution. Apical sealing was assessed by microleakage of 50% silver nitrate solution. Roots were longitudinally sectioned in a buccolingual plane and analyzed using an operating microscope (20× magnification). Depth of dye leakage into the dentinal walls was measured in millimeters. Results were analyzed using ANOVA and Tukey's test (P = 0.05). MTA Bio plus distilled water showed significantly higher mean leakage results (1.06 mm) when compared with MTA Bio plus doxycycline (0.61 mm), and higher, although not significant, results when compared with MTA Bio plus chlorhexidine (0.79 mm). In conclusion, replacing distilled water with two biologically active mixing agents (doxycycline and chlorhexidine) did not alter the sealing properties of MTABio. The antimicrobial properties of these combinations should be further investigated.

Torsional resistance of retreatment instruments.

INTRODUCTION: This study compared the torsional resistance of two brands of rotary nickel-titanium (NiTi) instruments indicated for endodontic retreatment. METHODS: Mtwo retreatment instruments #15 and #25 (VDW, Munich, Germany) and ProTaper Universal retreatment instruments D2 and D3 (Maillefer/Dentsply, Ballaigues, Switzerland) were subjected to a torsional assay in clockwise rotation. The two parameters evaluated were maximum torque and angular deflection at failure. Fractured instruments had their fractured surfaces and helical shafts examined by scanning electron microscopy. RESULTS: The results indicated that the angular deflection at fracture decreased in the following order: Mtwo retreatment file #15 > Mtwo retreatment file #25 > ProTaper Universal retreatment file D2 > ProTaper Universal retreatment file D3. As for the maximum torque values, the results revealed the following descending order: ProTaper Universal file D2 > Mtwo retreatment file #25 > ProTaper Universal file D3 > Mtwo retreatment file #15. Scanning electron microscopic analysis revealed that plastic deformation occurred along the helical shaft of the fractured instruments. Fractured surfaces were of the ductile type. CONCLUSIONS: The instruments tested showed different torsional behavior depending on the parameter evaluated. If one considers that high angular deflection values may serve as a safety factor, then the Mtwo retreatment instruments showed significantly better results.

Single-session use of mineral trioxide aggregate as an apical barrier in a case of external root resorption.

External root resorption may occur as a consequence of trauma, orthodontic treatment, bacterial infection or incomplete sealing of the root canal system (bacterial re-infection), and lead to crater formation on the resorbed apex. This would deform the root apex surface, and cause loss of apical constriction. Depending on the extent of the resorptive process, different treatment regimens have been proposed. A 34-year-old male patient presented with an intra-radicular retainer and an inadequate filling on tooth #21, as well as a radiographic image suggesting periapical bone rarefaction. After root canal retreatment, the defect was accessed coronally. The resorption area was chemo-mechanically debrided and since the apical end was very wide, a calcium sulphate matrix was made. Mineral trioxide aggregate (MTA) was used to fill the resorptive defect, and the coronal access was temporarily sealed. After 24 h, the quality of the apical seal was evaluated with the aid of an operating microscope, and then the root canal system was filled. A 12-month follow-up radiograph showed adequate repair of the resorption. Clinically, the tooth was asymptomatic. We concluded that MTA can be successfully used to avoid overextension of the filling material when treating a tooth with external resorption.