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Endodontic retreatment can be a challenging task that can result in many complications if not approached cautiously. Many of these difficulties revolve around regaining access to the pulp chamber through extensive coronal restorations and removing residual root filling material, the commonest being gutta-percha (GP), from within obturated canals. This can often be an untidy, time consuming process that places teeth at a greater risk of iatrogenic injury and inhibits the operator achieving the necessary chemical disinfection required to eliminate the persistent apical disease. Therefore the following article aims to aid practitioners, particularly those who are unfamiliar, with accessing and removing GP from endodontically treated teeth. The outlined systematic approach is accessible in general practice, where the vast majority of endodontic treatment is conducted, requires basic equipment and with the correct experience can be applied to both straight and curved canals. By overcoming this initial stage of retreatment, subsequent chemical disinfection, which is critical to success, can be carried out to a higher standard reducing risks of re-infection.

Objective To evaluate the ability of apex locators as a tool in determining working length in comparison to traditional working length radiographs in general dental practice. Design Randomised controlled clinical trial. Setting General dental practices in the North West of England. Subjects Adults requiring root canal treatment of at least one tooth with minimal or moderate difficulty. Intervention Root canal treatment was carried out with the working length determined by apex locator in the treatment group (AL), and periapical radiograph in the control group (PA). Outcome measure The acceptability of the master cone gutta percha measured from a radiograph before obturation was used as the primary outcome. Results Twenty-one of 23 fillings in the AL group were judged as acceptable, compared to 17 of 23 fillings in the PA group. This difference was not statistically significant. Conclusion In general dental practice, no significant difference was found in working length determined using apex locator combined with a master cone GP radiograph or using the conventional method. There is a need for larger trials to investigate these methods further.

The purpose of the obturation phase of a root filling is two-fold; to prevent microorganisms from re-entering the root canal system, and to isolate any microorganisms that may remain within the tooth from nutrients in tissue fluids. The seal at the apical end of the root canal is achieved by a well-fitting gutta-percha master point, and accessory points, although heated techniques may result in a better seal. The seal at the coronal end is achieved by the application of a layer of resin-modified glass ionomer cement as accessory canals may lead from the floor of the pulp chamber to the furcation area. It must always be remembered that success will only be achieved if the root canal system has been as thoroughly debrided as possible of infected material.

Objective The objective of this study was to investigate the outcome of conventional root canal treatment in a general practice setting within the Royal Air Force dental service. Design Retrospective review. Methods Teeth that had been root-filled for 12 months or more by Royal Air Force dental practitioners in patients attending a large Royal Air Force dental centre were included in the study. Following clinical and radiographic review the root fillings were classified as 'definitely successful', 'probably successful' or 'failed'. The effect on success of several variables on the outcome was investigated. Results Out of a total of 406 teeth, 59% were maxillary teeth and 41% were mandibular teeth. Sixty-nine per cent of the total sample had pre-existing periapical radiolucencies. Cold lateral condensation of gutta-percha was the most widely used filling technique (64% of all cases). Fifty per cent of the teeth had root fillings within 2 mm of the radiographic apex, 32% were greater than 2 mm from the radiographic apex and 18% were overfilled. Cold lateral condensation was the most successful (92% overall) filling technique. Maxillary anterior teeth had a better success rate (96%) than other tooth types. Teeth with pre-existing periapical radiolucencies had a higher success rate (87%) than those cases where there was no pre-existing periapical radiolucency (80%). Root fillings that were less than 2 mm from the radiographic apex of the tooth had a higher success rate (88% overall) than those that were greater than 2 mm from the radiographic apex (77% overall). Of the 406 cases, 57% (n=231) were classified as definitely successful, 28% (n=114) were classified as probably successful and 15% (n=62) were classified as failures. Thus, the overall success rate combining definitely successful and probably successful root fillings was 85% (n=344). Conclusions Root fillings placed using cold lateral condensation of gutta-percha to within 2 mm of the radiographic apex of the tooth were associated with the best outcome.

Objective This study was designed to investigate the effect of certain pathological alterations of the dental structures (diminishing bone support, internal resorption, root perforation, periapical lesion) on stress distribution during root canal filling procedures by the warm vertical compaction technique. Design The computer stress analyses were done for a maxillary canine tooth model which was based on dimensions recovered from a human cadaveric maxilla scanned by CT. Methods The finite element method was used to calculate the stresses generated during root canal filling procedures by warm vertical compaction technique. Patterns of stress distribution associated with various alterations in dental structures were investigated. For this purpose 60 cases were simulated. The hypothetical force of 10 N is taken as a unit representation. For other magnitudes of applied force, the corresponding stresses would be scaled directly because the calculations were made for linear materials. Results and Conclusion It is found that, when diminishing bone support and internal resorption are concurrently simulated, a marked increase in stress magnitudes occur (maximum von Mises stress 5.37 N/mm2). However, these values still remain much below the most frequently reported tensile strength of dentine (50–100 N/mm2). If dentist's handwork is transformed into equivalent edge tractions on gutta-percha, then stresses in dentine, even when they are corrected for 3-kg applied force, appear to remain below fracture strengths of this material. This result leads us to conclude that when warm vertical compaction technique is skilfully performed and inadvertent undue force is not applied, a premature root fracture in a large rooted maxillary anterior tooth with straight root canal anatomy is not likely to occur, even for the unfavourable conditions simulated in our model. This result, like all results derived from modelling applications, is of course contingent upon agreement between the way in which the clinical operations are performed and the way in which they are mirrored for computer representation. We believe that the approach described here avoids the spurious stresses that have been reported in similar investigations.

Objective: To investigate the distribution of stresses that occur in a maxillary canine tooth during vertical and lateral condensation of gutta-percha in the root canal. Design: An elaborate three-dimensional finite element model of a maxillary canine tooth was developed for the purposes of stress analysis. A sample stress analysis was also performed to demonstrate the variations in stress values that occur between different solutions of the same problem. Methods: A 3D finite element analysis was performed on a maxillary canine tooth model which was created using the dimensions of computer tomographic scans of a cadaveric maxilla as reference. Results: If the manual operations of the endodontist are transcribed to the software by considering the finite size of the plugger or the spreader, then the maximum stresses generated in the dentine are much smaller than the reported tensile strength of this material. Conclusion: The causes of the fractures in the dentine reported by previous investigators must be traced to conditions which were not considered in this study. These include aspects of modelling, which is the most important single parameter on which the final results depend. Stresses calculated by means of the complicated 3D model appear to agree with those recovered from a simpler 2D idealisation

Root canal treatment is achieved by chemo-mechanical debridement of the root canal system followed by filling. The filling material 'entombs' residual bacteria and acts as a barrier which prevents the entrance of oral microorganisms and reinfection of the root canal system through microleakage. However, filling with contemporary root filling materials such as gutta-percha offers limited long-term resistance to microorganisms; as a result other materials such as Resilon have been investigated as alternatives. The aim of this review was to analyse the literature to consider whether Resilon is a suitable root canal filling material. A MEDLINE and Cochrane library search including various keyword searches identified several papers which investigated or discussed Resilon or RealSeal/Epiphany. Analysis of the literature demonstrated that the bulk of the literature is in vitro in nature, based largely on leakage-type studies, and demonstrates a wide variety of methodologies with conflicting findings; as a result meaningful conclusions are difficult. Within the limit of these in vitro studies Resilon appears to perform adequately in comparison to gutta-percha, however, as a result of the questionable merit of such studies, it cannot presently be considered an evidence-based alternative to the current gold standard gutta-percha. It is imperative that before Resilon is considered as a replacement material, a better understanding of the physical properties of the resin sealer and the reality of the adhesive 'monoblock' are elucidated. The literature also demonstrates a paucity of quality long-term clinical outcome studies which will need to be addressed before firm conclusions can be reached.

Objective To compare apical microleakage of MTA following reverse retrograde root filling with that following amalgam and EBA retrofilling. Design Prospective random control trial. Setting It was conducted at the University of Jordan in 1998. Materials and methods The root canals of 79 extracted teeth were instrumented and obturated with vertically condensed gutta-percha. Each tooth was apically resected and the apex was prepared ultrasonically to 3 mm depth and the root surface isolated with nail varnish. Teeth were divided randomly into three groups of 25 teeth each. First group was retrofilled with amalgam, second group with EBA and the third group with MTA. Following immersion in 1% methylene blue dye for 72 hours, the roots were sectioned and the depth of dye penetration was evaluated by a stereomicroscope at x10 magnification. Interventions Super EBA is a reinforced zinc oxide cement based on a mixture of 32% eugenol and 68% ethoxy benzoic acid (EBA). MTA is a mineral trioxide aggregate cement (MTA) based on a mixture of sterile water. Main outcome measures The sealing effectiveness of the retrograde filling materials used in this study was determined by their ability to inhibit dye penetration. Results 56% of the group filled with amalgam and 20% of the group filled with EBA showed dye leakage beyond the retrofilling material whereas the MTA group showed none, two samples from MTA group were eliminated because of their fractured roots. The chi-squared test revealed a statistically significant difference among all three groups (P < 0.05). Conclusion MTA cement provides a better seal than amalgam and EBA cement when used as retrograde filling, but the extrapolation of this result into a clinical practice may be questionable.

Failure of root canal treatment and/or post crowns can be avoided in many cases if appropriate tooth preparation is carried out. This paper discusses the rationale for the timing of post placement following root canal treatment and appropriate methods for removal of gutta-percha prior to post space preparation. The basic principles of post space preparation are described, which should reduce the risk of weakening the root unnecessarily, causing damage to the periodontium and post perforation.

This paper highlights one aspect of a presentation to be given at the BDA Conference and is written in the context of dentistry in primary care. Careful oral health assessment as a foundation to good treatment planning and quality dentistry is not new, but there are a number of important new perspectives emerging across countries and healthcare systems in terms of the content and role of such an assessment in modern dental practice.

Endodontic material inadvertently forced into the inferior dental canal during root-canal therapy can cause damage to the underlying nerve. The effect of toxic filling materials on nervous tissues has been well publicised, however, the thermal and pressure changes produced by chemically bland materials has not been adequately highlighted. In the case reported, thermoplasticised gutta percha was inadvertently introduced into the canal during endodontic treatment of a lower molar. Factors affecting the outcome are discussed and guidelines are presented for the management of such a case with reference to surgery against observation.