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Enterococcus faecalis is often involved in the aetiology of apical periodontitis after endodontic treatment. This project aimed to establish, on dentine in vitro, a multi-species biofilm containing E. faecalis, and to determine if the organism had an increased resistance to sodium hypochlorite compared with an axenic biofilm. Biofilms were established on dentine discs in flow cells with either E. faecalis alone (axenic) or together with Fusobacterium nucleatum and Streptococcus sanguinis. Following treatment with either 0.9% sodium hypochlorite or saline, the viability of E. faecalis was determined by serial plating and qualitative analysis was performed by scanning electron microscopy and confocal laser scanning microscopy. Viable counts indicated that 0.9% NaOCl is highly effective against E. faecalis grown alone and as part of a multi-species biofilm (P = 0.0005 and P = 0.001, respectively). No significant difference in its survival in the two biofilm types was found (P = 0.8276)., (© 2014 Australian Society of Endodontology.)

This study sought to assess if the final rinse protocol interferes with the smear layer removal in the apical area of curved canals. Sixty-four extracted human mandibular molars with curved mesial roots were instrumented with rotary files and divided into six experimental groups for final rinse: 1EDTA (syringe irrigation with 1 mL of 17% ethylenediaminetetraacetic acid (EDTA) ), 5EDTA (syringe irrigation with 5 mL of 17% EDTA), 1EDTA-P (syringe irrigation with 1 mL of 17% EDTA + pumping with gutta-percha point), 5EDTA-P (syringe irrigation with 5 mL of 17% EDTA + pumping with gutta-percha point), 1EDTA-EA (syringe irrigation with 1 mL of 17% EDTA + EndoActivator) and 5EDTA-EA (syringe irrigation with 5 mL of 17% EDTA + EndoActivator). Final rinsing was carried out over 3 min. The specimens were split lengthwise and observed under a scanning electron microscope using a score criterion. Comparison among the groups showed statistically significant difference only between the 5EDTA-EA group and the other groups (Kruskal-Wallis and Dunn's post-hoc tests, P < 0.05). The combination of 5 mL of 17% EDTA and 3 mL of 2.5% sodium hypochlorite (NaOCl) with the EndoActivator removed smear layer from the apical area of curved root canals more effectively than the other protocols used., (© 2013 Australian Society of Endodontology.)

The purpose of the study was to test the hypothesis that air entrapment occurs in the apical third of a root canal during irrigation. A second objective was to test the null hypothesis that there is no difference between laser-driven irrigation (an erbium, chromium:yttrium-scandium-gallium-garnet laser) and passive ultrasonic irrigation in removing an airlock from the apical third. One hundred twenty extracted human teeth with single narrow root canals were randomised into two experimental groups (n = 40) and two control groups (n = 20). The specimens were shaped using hand instruments up to a size 30/0.02 file. The teeth were irrigated with a mixture of saline, radiopaque contrast and ink in solution. In the passive ultrasonic irrigation group, the irrigant was activated with an ultrasonic device for 60 s. In the laser group, the irrigant was activated with a laser for 60 s. It was concluded that if the insertion of irrigation needle is shorter than the working length, air entrapment may develop in the apical third, but the use of laser-driven irrigation is completely effective in removing it., (© 2013 The Authors. Australian Endodontic Journal © 2013 Australian Society of Endodontology.)

The objective of this study was to compare the antimicrobial activity of sodium hypochlorite (NaOCl), chlorhexidine gluconate (CHX) and octenidine hydrochloride (OCT) in different concentrations against endodontic pathogens in vitro. Agar diffusion procedure was used to determine the antimicrobial activity of the tested materials. Enterococcus faecalis, Candida albicans and the mixture of these were used for this study. In the agar diffusion test, 5.25% NaOCl exhibited better antimicrobial effect than the other concentrations of NaOCl for all strains. All concentrations of OCT were effective against C. albicans and E. faecalis. Some 0.2% CHX was ineffective on all microorganisms. Antibacterial effectiveness of all experimental solutions decreased on the mixture of all strains. Decreasing concentrations of NaOCl resulted in significantly reduced antimicrobial effect., (© 2010 The Authors. Australian Endodontic Journal © 2010 Australian Society of Endodontology.)

The aim of this study was to evaluate the antimicrobial capacity of sodium hypochlorite (1% and 5%) and chlorhexidine (0.12%, 0.5% and 1%) with or without the addition of organic material (bovine serum albumin, BSA) against some bacterial samples (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Porphyromonas gingivalis and Fusobacterium nucleatum) using two activity tests (contact and diffusion agar tests). In the contact test (first model), bacterial samples were kept in contact with each irrigating solution for different time intervals: immediately (t(0)), 5 min (t(5)), 15 min (t(15)) and 30 min (t(30)). The agar diffusion test was the second model used. In half the specimens, 0.5% BSA was added to simulate organic tissue present in the root canal. Bacterial growth was evaluated for each microorganism and activity test. Each test was repeated 10 times. In the contact test, 0.12% chlorhexidine solution (CHX) did not eliminate E. faecalis at any tested time. CHX at 0.5% eliminated all strains except E. faecalis after immediate contact. All strains were eliminated by 1% CHX, 1% NaOCl and 5% NaOCl. BSA did not interfere with the antimicrobial activity of the irrigating solutions. In the agar diffusion test, all solutions exhibited zones of antimicrobial activity; however, BSA interfered with the antimicrobial activity of NaOCl and CHX. Under the condition of the contact test, the 0.12% CHX was ineffective in eliminating E. faecalis, while 0.5% CHX, 1% CHX, 1% NaOCl and 5% NaOCl showed antibacterial effectiveness against all the tested bacterial strains. The addition of an organic load interfered with the accuracy of the agar diffusion test.

The purpose of this in vitro study was to compare the efficacy of 24% ethylenediaminetetraacetic acid (EDTA) gel and 17% EDTA solution in cleaning dentine walls after root canal instrumentation. Thirty human canine teeth were divided into three groups of 10 teeth each. In Group 1, 1% sodium hypochlorite was used as the irrigating solution; in Group 2, 1% sodium hypochlorite was used with 17% EDTA solution; and in Group 3, 1% sodium hypochlorite was used with 24% EDTA gel. The presence of a smear layer was analysed after instrumentation using scanning electron microscopy. The Kruskal-Wallis test revealed a statistical difference (P < 0.05) between Groups 1 and 2, and also between Groups 1 and 3. No difference was observed between Groups 2 and 3 (P > 0.05). The results indicate that 1% sodium hypochlorite alone does not remove the smear layer and that there was no statistical difference between EDTA gel and EDTA solution in smear layer removal.

The cleaning capacity of rotary Ni-Ti instrumentation using Profile GT files, coupled with irrigation energised by ultrasound, was evaluated. Thirty-six human mandibular incisors were instrumented in vitro using the crown-down technique with the Profile GT system to 1 mm from the anatomical apex to a size 30.04 taper file. The instrumented teeth were then divided randomly into four groups where various final irrigations were used: Group I: 100 ml of 1% NaOCl with a Luer-Lok syringe (control group); Group II, Group III and Group IV: final irrigation with 100 ml of 1% NaOCl energised by ultrasound for 1, 3 and 5 min, respectively. After biomechanical preparation, the apical thirds of the roots were submitted to histological processing and examination. The specimens were analysed at 40x magnification and the images submitted to morphometric analysis with an integration grid. anova showed a statistically significant difference (P < 0.01) between the irrigation techniques. Group I (Luer-Lok syringe) showed the highest percentage of debris (35.81 +/- 4.49) and was statistically different from the other groups energised by ultrasound: Group II (27.28 +/- 4.49), Group III (24.39 +/- 5.72) and Group IV (18.46 +/- 5.25). It was concluded that rotary instrumentation using Ni-Ti files associated with final irrigation of 1% NaOCl energised by ultrasound leads to better debris removal from the apical third of mesio-distally flattened root canal.

The benefits of using sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) as endodontic irrigants, and calcium hydroxide as an inter-appointment medicament, are well known to dentists. Many steps undertaken during endodontic treatment and retreatment are rather mechanical in nature, and less attention is committed to understanding the biological issues underlying endodontic treatment and retreatment. It should be noted that dentine is the fundamental substrate in endodontic treatment, and its properties and characteristics are the key determinant of nearly all disease and post-disease processes in the teeth. In this article the effects and counter-effects of NaOCl and EDTA on root canal dentine, and some other related issues are reviewed. This information will enable clinicians to use the beneficial effects of these chemicals, while necessary steps are considered to reduce their harmful effects on dentine substrate.