Guidelines for non-surgical root canal treatment.

Guidelines were developed by the Australian Society of Endodontology Inc. with the intent to describe relevant aspects of contemporary evidence-based root canal treatment. The document aims to support clinicians by describing a Standard of Practice in the Australian context. The presented guidelines refer to Competence criteria and Quality standards for the main steps in root canal treatment. While the intent is not to replace individual clinical decision-making, it is envisaged that these periodically reviewable guidelines may help to improve clinical outcomes.

Quorum Sensing and Quorum Quenching with a Focus on Cariogenic and Periodontopathic Oral Biofilms.

Numerous in vitro studies highlight the role of quorum sensing in the pathogenicity and virulence of biofilms. This narrative review discusses general principles in quorum sensing, including Gram-positive and Gram-negative models and the influence of flow, before focusing on quorum sensing and quorum quenching in cariogenic and periodontopathic biofilms. In cariology, quorum sensing centres on the role of Streptococcus mutans, and to a lesser extent Candida albicans, while Fusobacterium nucleatum and the red complex pathogens form the basis of the majority of the quorum sensing research on periodontopathic biofilms. Recent research highlights developments in quorum quenching, also known as quorum sensing inhibition, as a potential antimicrobial tool to attenuate the pathogenicity of oral biofilms by the inhibition of bacterial signalling networks. Quorum quenchers may be synthetic or derived from plant or bacterial products, or human saliva. Furthermore, biofilm inhibition by coating quorum sensing inhibitors on dental implant surfaces provides another potential application of quorum quenching technologies in dentistry. While the body of predominantly in vitro research presented here is steadily growing, the clinical value of quorum sensing inhibitors against in vivo oral polymicrobial biofilms needs to be ascertained.

Resistance to compressive force in continuous chelation.

Continuous chelation involves the simultaneous use of sodium hypochlorite and a chelating agent. Given the combination of a proteolytic agent and a demineralising chelator, this study aimed to investigate whether mixtures containing the weak chelators etidronate or clodronate and sodium hypochlorite could adversely affect the mechanical strength of teeth compared to the sequence sodium hypochlorite/EDTA/sodium hypochlorite. Matching pairs of bovine teeth were tested on a universal testing machine, and the compressive load at fracture was recorded. One root from each pair was prepared with the sequence, and the matching tooth was prepared with either water, the clodronate mixture or the etidronate mixture. No differences in load at fracture were seen between either mixture and the sequence. However, loads were higher in the teeth irrigated with water compared to the sequence. The results indicated that the continuous chelation mixtures did not alter tooth mechanical properties compared to the standard sequence.

Multiple assessment methodologies in determining the antibiofilm actions of sodium hypochlorite mixed with clodronate or etidronate in endodontic irrigation.

This study aimed to use multiple methodologies, including a novel usage of scanning electron microscopy (SEM), to evaluate the antimicrobial actions of sodium hypochlorite (NaOCl) admixed with clodronate or etidronate in root canal irrigation. The study also examined the usefulness of colony counting as a biofilm assessment methodology. Seven day Enterococcus faecalis biofilms were grown on hydroxyapatite discs. The discs were disinfected with 0.26 M clodronate-5% NaOCl, 0.26 M etidronate-5% NaOCl, 5% NaOCl, or treated with phosphate buffered saline (PBS). Assessments were performed using colony counting, SEM and the XTT reduction assay. The XTT assessment used the same groups but with 2.5% NaOCl. For colony counting, bacteria were removed from the discs by vortex mixing, followed by plating. The discs were subsequently fixed for SEM imagining and evaluators scored the SEM micrographs for remaining bacteria. Antibiofilm actions were assessed with the Kruskal-Wallis and Dunn's multiple comparison tests. SEM micrographs and the XTT assay revealed no differences between the NaOCl controls and the clodronate or etidronate mixtures with NaOCl (P > 0.05). It was concluded that the chelator mixtures with NaOCl had antibiofilm actions comparable to NaOCl. Furthermore, vortex mixing incompletely removed biofilm from HA discs in the PBS controls and hence colony counting using E. faecalis biofilms on hydroxyapatite discs could not be used for intergroup comparisons involving PBS. Additionally, colony counting could not be used for comparisons between the NaOCl treatment groups because the removal of bacteria from the substrate by vortex mixing was affected by the irrigant type.

The effect of temperature on the stability of sodium hypochlorite in a continuous chelation mixture containing the chelator clodronate.

This study evaluated the stability of continuous chelation mixtures of clodronate admixed with sodium hypochlorite at room temperature (23°C), at root canal temperature (34-35°C) and in refrigerated storage (2-4°C). In continuous chelation, one solution containing a chelator and sodium hypochlorite simultaneously disinfects and removes organic matter and smear layer. This technique is thought to enhance antimicrobial action and debris removal. However, hypochlorite stability and free available chlorine (FAC) levels may decline with elevated temperature and through chemical interactions with the chelator, thus reducing the therapeutic window of these mixtures. Employing iodometric titration, the FAC for clodronate-hypochlorite mixtures was measured at 34-35°C, 23°C and 2-4°C. Clodronate-hypochlorite solutions were stable for 180 min at 34-35°C. When kept at 2-4°C over 3 months, they maintain 95% of the FAC compared with baseline. It was concluded that the therapeutic window of clodronate-hypochlorite mixtures is unaffected at root canal temperature.

Organic Tissue Dissolution in Clodronate and Etidronate Mixtures with Sodium Hypochlorite.

INTRODUCTION: Mixtures of clodronate with sodium hypochlorite (NaOCl) better maintain free available chlorine (FAC) than etidronate-hypochlorite mixtures. This research aimed to compare organic tissue dissolution and residual FAC between clodronate and etidronate mixtures. Additionally, clodronate-hypochlorite mixtures lose no FAC over several hours. The second aim was to examine how well such mixtures dissolve organic material 6 hours from mixing. METHODS: Soon after mixing, porcine palatal mucosa samples were added to 32°C solutions containing 0.26 mol/L clodronate and 5% NaOCl (0.26 mol/L-5% NaOCl), 0.26 mol/L etidronate-5% NaOCl, 5% NaOCl, 0.26 mol/L clodronate, 0.26 mol/L etidronate, or phosphate-buffered saline. Weights and FAC, where applicable, were recorded initially and at 15 minutes. FAC was measured by iodometric titration. Secondly, 6 hours after mixing, mucosa was added to 0.26 mol/L clodronate-2.5% NaOCl, 2.5% NaOCl, 0.52 mol/L clodronate-5% NaOCl, 5% NaOCl, or phosphate-buffered saline. Sample weights at 0, 5, 10, and 15 minutes were recorded. Analysis of variance was used for statistical analyses (α < .05). RESULTS: Soon after mixing, 0.26 mol/L clodronate-5% NaOCl dissolved mucosa as well as 5% NaOCl and better than 0.26 mol/L etidronate-5% NaOCl compared with which it retained more FAC. At 6 hours after mixing, 0.26 mol/L clodronate-2.5% NaOCl dissolved organic material as well as 2.5% NaOCl. However, 0.52 mol/L clodronate-5% NaOCl dissolved less mucosa than 5% NaOCl. CONCLUSIONS: Soon after mixing, clodronate mixtures better dissolve organic material than etidronate mixtures and have higher residual FAC. Six hours from mixing, 0.26 mol/L clodronate-2.5% NaOCl mixtures dissolve organic material similarly to controls.

The Effect of Heating to Intracanal Temperature on the Stability of Sodium Hypochlorite Admixed with Etidronate or EDTA for Continuous Chelation.

INTRODUCTION: Tetrasodium etidronate (Na4 etidronate) and tetrasodium EDTA (Na4 EDTA) are chelators that can combine with sodium hypochlorite (NaOCl) as a 1-mix endodontic irrigant in a process called continuous chelation. The therapeutic window of these mixtures is determined by the chemical reaction between NaOCl and the chelator. At room temperature, this window is 60 minutes for Na4 etidronate and 30 minutes for Na4 EDTA. Because reaction kinetics are influenced by heat, this study assesses the influence of heating to an intracanal temperature of 35°C on the therapeutic window in continuous chelation. METHODS: The loss of free available chlorine (FAC) in NaOCl mixtures with Na4 etidronate or Na4EDTA was determined by iodometric titration at 23°C ± 0.7°C (23°C) and 34.6°C ± 0.3°C (35°C) at 1, 20, 40, and 60 minutes after mixing. The pH and temperature of the mixtures were measured. RESULTS: At 23°C, 18% Na4 etidronate/5% NaOCl solutions at 20, 40, and 60 minutes lost 4%, 9% and 18% FAC, and at 35°C, they lost 20%, 68% and 92% FAC; 5% Na4 EDTA/2.5% NaOCl solutions at 20, 40, and 60 minutes at 23°C lost 88%, 94%, and 97% FAC, and at 35°C, they lost 96%, 99%, and 100%. Decreases in FAC were accompanied by pH declines. CONCLUSIONS: The effect of heating to 35°C from a room temperature of 23°C on 18% Na4 etidronate/5% NaOCl solutions reduces its therapeutic window to 20 minutes. Solutions of 5% Na4 EDTA/2.5% NaOCl are not useful in the continuous chelation technique. Tracking pH changes could be used to estimate NaOCl degradation.

Alkaline Sodium Hypochlorite Irrigant and Its Chemical Interactions.

Endodontic irrigating solutions may interact chemically with one another. This is important, because even when solutions are not admixed, they will come into contact with one another during an alternating irrigation technique, forming unwanted by-products, which may be toxic or irritant. Mixing or alternating irrigants can also reduce their ability to clean and disinfect the root canal system of teeth by changing their chemical structure with subsequent loss of the active agent, or by inducing precipitate formation in the root canal system. Precipitates occlude dental tubules, resulting in less penetration of antimicrobials and a loss of disinfection efficacy. Sodium hypochlorite is not only a very reactive oxidizing agent, but is also the most commonly used endodontic irrigant. As such, many interactions occurring between it and other irrigants, chelators and other antimicrobials, may occur. Of particular interest is the interaction between sodium hypochlorite and the chelators EDTA, citric acid and etidronate and between sodium hypochlorite and the antimicrobials chlorhexidine, alexidine, MTAD and octenisept.