ENDO, 03/2012

The objective of this paper is to review the various methods used to study and understand root canal systems. The complexity of root canal morphology presents a challenge to any clinician. Any attempt to perform root canal therapy must be preceded with a thorough understanding of the anatomy of both the pulp chamber and the root canal system. Several methods have been used to examine the root canal system ranging from in vitro methods such as sectioning of teeth, metal castings to advanced in vivo tomographic imaging, along with the use of magnification. Successful root canal therapy requires an in depth knowledge of root canal morphology. False assumptions about the root canal anatomy of teeth may lead to misdiagnosis, missed canals, improper debridement and breakage of root canal instruments during root canal treatment. Keywords: anatomy, imaging, morphology, root canal, tomography

Aim: The aim of the present study was to evaluate in vitro the accuracy of the Mini Apex Locator (Sybron-Kerr, Romulus, USA), Novapex (Forum Technologies, Rishon Le-zion, Israel) and ProPex II (Dentsply-Maillefer, Ballaigues, Switzerland) electronic apex locators compared with the radiographic method to determine the working length. Methodology: The mesiobuccal root canals of 30 extracted human mandibular first molars were used. The actual length was determined visually under magnification. A glass container was filled with sterile 0.9% NaCl solution and the specimens were fixed to a plastic bar using acrylic resin. The apical constriction of the teeth was determined with three electronic apex locators and radiographically. The same procedures were performed 1 mm short of the apical foramen. Each measurement was repeated three times and the mean value computed. These values were tabulated for comparison with the measurements obtained by the electronic and radiographic methods with the actual length. Data were analysed statistically by McNemar test at the 5% significance level. Results: The highest coincidence percentage was found with the ProPex II device (83.0%), followed by the radiographic method (46.7%), Novapex (30%), and Mini Apex Locator (13.3%) in relation to the visual determination of the apical constriction. At 1 mm short of the apical foramen, the highest coincidence percentage occurred with the ProPex II device (80.0%), radiographic method (56.7%), Novapex (26.7%), and Mini Apex Locator (6.7%). There were statistically significant differences between the methods used. Conclusions: ProPex II showed the highest accuracy in determining the working length, followed by the radiographic method, Novapex and Mini Apex Locator. Keywords: apical constriction, electronic apex locator, ProPex II, radiography, working length determination

Aim: During retreatment procedures, the bulk of root canal filling material can easily be removed within 2-3 min using rotary instruments. Nevertheless, a residue consisting of gutta-percha and sealer is often retained, attached to the canal walls. This residue has to be mechanically removed. The aim of the present study was to test the hypothesis that a short, 1-2-min exposure of set epoxy resin-based sealers to chloroform or xylene would soften them to an extent that may facilitate their mechanical removal. Materials and methods: Twenty samples were prepared from either AH 26 (Dentsply-DeTrey, Konstanz, Germany) or AH Plus (Dentsply-DeTrey, Konstanz, Germany) sealers and allowed to fully set. The surfaces of these samples were exposed for 1 or 2 min to either chloroform or xylene, and their surface hardness tested using the Vickers hardness test. The samples were also weighed before and after the exposure to the solvents, to measure their solubility. Analysis of variance with repeated measures was performed with Tukey's post hoc test for analysis of the results. Results: AH 26 and AH Plus did not differ from each other in their initial hardness. Chloroform softened both sealers within 2 min to 9% of their original hardness (P 0.0001). Xylene softened AH Plus to 19% of its original hardness (P 0.0001), whereas AH 26 was almost unaffected by this solvent, maintaining 89% of its original hardness (P > 0.05). Neither of the sealers lost weight during the 2 min exposure to the solvents. Conclusions: No solubility of the sealers was recorded during a 2 min exposure to either chloroform or xylene. Nevertheless, chloroform was found to be an effective and fast softener for both sealers. Xylene was an effective softener for AH Plus, but not for AH 26. Keywords: AH 26, AH Plus, chloroform, re-treatment, xylene

Adequate knowledge on the root and root canal morphological variations is essential for successful endodontic treatment. Mandibular molar teeth show considerable variability and complexity in their external and internal radicular morphology that require special attention from dental practitioners to provide the best clinical outcomes for the patients. This report aims to describe two clinical cases of mandibular molar teeth with accessory mesial roots/root canals. The first case demonstrates a successful identification and endodontic management of a three-rooted mandibular second molar with an accessory mesial root, and the second case presents a mandibular first molar with five root canals, in which three separate mesial root canals were identified. With the aid of SEM and radiographic examination, both external and internal radicular morphological analysis were also performed on an extracted mandibular second molar tooth having an apical mesial root bifurcation. In addition, a review on the literature was undertaken to identify the available in vitro and in vivo studies that demonstrated these anatomical aberrations in the mesial root of mandibular molar teeth. Keywords: accessory root, accessory root canal, mandibular molar, middle mesial canal, root, root canal

This case report deals with the endodontic treatment of a relatively uncommon clinical case, i.e., the treatment of three canals with three separate foramina in both the first and the second mandibular premolars in the same patient. It is further concluded that for such a treatment to be successful, an accurate diagnosis of the morphology of the root canal system should first be reached and, accordingly, some resources such as radiographs, cone beam computed tomography (CBCT) as well as the operating microscope should necessarily be made use of. Keywords: cone beam computed tomography, mandibular first premolars, mandibular second premolars, operating microscope, three canals, three foramina

This report presents a case with unusual root morphology on both first mandibular molars. Normal root canal anatomy of mandibular first molars is characterised by a birooted tooth with three root canals. A peculiarity that may occur, however, is radix entomolaris (RE). An endodontic retreatment was carried out on the two mandibular molars of a female patient. In both cases, an additional distally located root was found and treated. Consequently, both teeth had three roots, each with four canals. Looking for accessory roots, root canals, and unusual anatomy of the canal system is decisive for a successful root canal treatment. Knowing that they exist enables a successful treatment to be provided, even in complicated cases. Keywords: radix entomolaris, retreatment, three-rooted mandibular first molar

Teeth with a history of non-successful surgical retreatment may present with particular difficulties in terms of treatment planning and procedures. The presented cases illustrate the successful treatment of two maxillary central incisors following previous surgery and insertion of transfixation pins. A combined non-surgical and surgical approach was undertaken to remove the root canal filling and the transfixation pins, and to achieve apical seal. Keywords: apicoectomy, microsurgery, post removal, root-end surgery, transfixation pin