ENDO, 01/2012

Adequate knowledge of both external and internal radicular anatomy is a fundamental prerequisite for successful endodontic therapy. Maxillary premolar teeth present an endodontic challenge due to their increased prevalence for root and root canal aberrations. This review aims to discuss the occurrence of accessory roots and root canals in maxillary premolar teeth and its relation to different ethnic groups. A new classification is proposed to include all their accessory root and root canal configurations. In addition, the endodontic considerations, including their identification and management, are discussed. Keywords: accessory root, classification, maxillary premolar teeth, root canal

Mineral trioxide aggregate (MTA) was first described in the dental scientific literature in 1993. Ever since it has been widely used for a number of applications in the field of dentistry. The aim of this literature review is to update previously published information and present a comprehensive list of articles from Nov 1993 to Dec 2010 regarding the biological properties, clinical applications and drawbacks of MTA. Keywords: biological properties, mineral trioxide aggregate (MTA), perforations, pulp capping

Shaping of the root canal is one of the most important stages of root canal treatment, which determines the ability to thoroughly disinfect and fill the root canal system. Numerous instruments have been designed for this purpose. Over the past twenty years, rotary nickel-titanium endodontic instruments have become the most prominent innovation in this field. This group of instruments possesses well-known advantages, compared with traditional stainless steel files. There are also some weaknesses, several of which could be explained by alloy characteristics and fabrication method, and others due to design characteristics. In the available literature, detailed information concerning design parameters and their influence on the instrument behaviour in the root canal is scarce. As a rule, a manufacturer's instructions are limited to some empirical recommendations for users. Meanwhile, understanding the instrument's properties and differences in its basic design features is essential for determining its operative abilities and correction of its disadvantages, by means of improving the technique or by taking into account its limitations, to avoid undesirable complications. Keywords: angles of cutting blade, cross section, design features, flute design, rotary nickel-titanium instruments, self-feeding effect, taper

perforAim: A new manufacturing method aimed at producing more flexible and resistant nickel titanium (NiTi) root canal instruments has been recently developed (CM-wire). The purpose of the study was to determine whether this new manufacturing method produces NiTi instruments (Hyflex) of superior flexibility, when compared with instruments produced by a traditional or thermally treated NiTi alloy. Materials and methods: Ten 0.06 size 25 Hyflex instruments (Coltène Whaledent, Langenau, Germany), ten 06.25 Vortex instruments (Dentsply-Tulsa, Tulsa, OK, USA) and ten 06.25 RaCe instruments (FKG, La Chaux-de-Fonds, Switzerland) were evaluated for stiffness on bending. Test procedures strictly followed recommendations from ISO specification 3630-1. Bending moments were measured when the instruments attained a 45-degree bend. All data obtained were recorded and statistically analysed using an ANOVA test, followed by a post-hoc Tukey (HSD) test. The level of significance was set at α = 0.05. Results: Statistical analysis showed that bending moments were significantly greater (P 0.05) for Vortex (mean value 57.58 g/cm) and RaCe (mean value 52.11 g/cm) instruments, compared to the Hyflex instruments (mean value 14.46 g/cm), thereby confirming the increased flexibility of the instruments produced with CM-wire alloy. Conclusion: Results of the present study demonstrate the ability of the new CM-wire manufacturing process to produce more flexible NiTi rotary instruments. Keywords: endodontic rotary instruments, mechanical properties, nickel titanium

Purpose: This study aimed to compare the influence of root canal preflaring using stainless steel K-files and rotary nickel-titanium (NiTi) PathFiles on the preservation of the original anatomy of the canals. The incidence of canal transportation and apical transportation were evaluated. Methods: A total of 60 root canals obtained from a pool of freshly extracted human mandibular and maxillary molars were divided into two groups. Each sample was placed on a mould, and pre-and post-instrumentation radiographs were taken. The radiographs were scanned and the angles of the root canal curvatures calculated using computer software (SIDEXIS 5.5/5.5×). Superimpositions were performed to calculate the apical root canal transportation. Results: The results were statistically analysed to compare the two techniques. Significant differences (P 0.05) regarding the two parameters evaluated were found between the two different instruments. The PathFile group showed significantly less canal transportation (P = 0.011) and less apical transportation (P 0.001). Conclusions: The results suggest that preflaring with PathFile NiTi rotary files maintained root canal anatomy better than stainless steel hand K-Files in severely curved canals, with curvatures greater than 30 degrees. Keywords: apical transportation, preflaring, root canal preparation, rotary files, stainless steel instruments

Aim: To investigate the efficiency of a newly introduced fibre root canal filling material as a post in comparison to metallic and fibre-reinforced posts. Materials and methods: Sixty maxillary central incisors were randomly assigned to six groups (n = 10). Groups 1, 2 and 3 were subjected to resistance-to-fracture tests and groups 4, 5 and 6 were subjected to resistance-to-dislodgement tests. In groups 1 and 4, the root canals were filled with newly introduced glass fibre root canal filling material (GF), and the excess filling above the cementoenamel junction was left to act as a post head. In groups 2 and 5, the canals were obturated using gutta-percha and fibre-reinforced posts (FPs). In groups 3 and 6, the canals were obturated using gutta-percha and metallic posts (MPs). For the groups subjected to fracture-resistance tests, restorative resin composite buildups and all-ceramic crowns were fabricated and cemented. These specimens were loaded until failure on the universal materials testing machine. For the dislodgement resistance testing, the post head was fixed to the testing machine by means of a special attachment, and the machine was run in a tension direction until the post was dislodged. Data was analysed using one-way analysis of variance (ANOVA) followed by Tukey post hoc tests. Significance was set at P = 0.05. Results: GF demonstrated the highest mean values of fracture and dislodgement resistance, followed by FP and MP. The fracture resistance values of both FP and GF were significantly higher than MP (P 0.001). There was no significant difference between FP and GF (P = 0.06). The dislodgement resistance values of GF, FP and MP were significantly different (P 0.001). Conclusions: GF can be used to fill the root canal in a single step and act as a post head to retain a plastic core with improved resistance to fracture. Keywords: bonding properties, fracture resistance, glass fibre, obturation, post

Aim: Undesirable complications can occur during endodontic procedures, compromising the success of therapy. This case report examines the management of procedural complications using mineral trioxide aggregate (MTA) in two mandibular molars with failed root canal treatment. Methods: In the first case, a lateral perforation in the mesial root of the mandibular left second molar associated with asymptomatic apical periodontitis was observed. The perforation was repaired with MTA and the mesiobuccal root canal filled with gutta-percha and sealer. In the second case, an apical canal transportation and perforation was identified in the mesial root of the mandibular right second molar associated with apical periodontitis. The root canals were prepared and an apical plug with MTA was made in the mesiobuccal root canal, followed by gutta-percha and sealer obturation. Results: The absence of clinical signs and symptoms and radiographic findings at the 3-year followup indicated a successful treatment of the first case. The tooth of the second case was asymptomatic and functional at the 4-year follow-up, and periapical repair was observed radiographically. Conclusions: The featured cases show that the treatment performed was able to resolve procedural complications during nonsurgical retreatment of morphologically complex teeth. Keywords: apical transportation, mineral trioxide aggregate, nonsurgical endodontic retreatment, root perforation

Taurodontism is a morpho-anatomical change in the shape of the tooth, in which the body of the tooth is enlarged and the roots are reduced in size. It is a rare dental anomaly affecting primarily the molars and is usually found in association with other anomalies or as a part of different syndromes. This anomaly, which was considered as a feature of primitive man, is also reported in modern man with a lower prevalence rate. This article presents a rare case of a female patient of 23 years who presented with taurodontism involving developed molars of all four quadrants, which was not associated with any other anomalies or syndromes.