ENDO, 03/2008

The purpose of this review is to describe the most commonly used anaesthetics in endodontology, their efficacy and methods of administration both in the maxilla and the mandible. The reasons why local anaesthesia cannot be achieved in all cases as well as the latest advances in anaesthetic techniques are also discussed. Keywords: inferior nerve block, infiltration anaesthesia, intraligamentary anaesthesia, intraosseous anaesthesia, pulpal anaesthesia, vasoconstrictor

The significance of corrosion of nickel-titanium instruments is controversial. There are still insufficient data on the clinical influence of the fracture behaviour of instruments. Impressive pictures of instruments that have been destroyed after being stored in sodium hypochlorite have been published, but this destruction is rarely seen clinically. This article provides a brief overview of the corrosion of nickel-titanium instruments. Keywords: corrosion, fracture, NaOCl, nickel-titanium, preparation

The objective of this study was to evaluate the fracture risk of ProTaper nickel-titanium (NiTi) rotary instruments under a continuous versus an alternating rotation when using the same instrumentation sequence. Plastic blocks with an embedded artificial root canal were used to investigate the fracture risk of NiTi instruments under a continuous rotation (360 degrees) and an alternating rotation (clockwise 60 degrees and counter-clockwise 45 degrees). A new instrument set was used until fracture of any instrument occurred. The number of times an instrument set and instrument type were used before fracture occurred was recorded and statistically evaluated. The results obtained in this investigation showed that the fracture risk of ProTaper instruments when used under continuous rotation was significantly higher (52.14% / P0.001) compared with use under an alternating rotation. Keywords: alternating rotation, continuous rotation, instrument separation, NiTi rotary instruments

Pyramidal teeth are thought to be a minor form of taurodontism, which is a morpho-anatomical change in the shape of a tooth, usually occurring in multirooted teeth as a result of failure of the infolding of the epithelial root sheet of Hertwig. The characteristic features of these teeth are an enlarged body and pulp chamber, as well as apical displacement of the pulpal floor. Endodontic treatment of a taurodont tooth is challenging, because it requires special care in handling, and in the identification of the number of root canals and morphology of the tooth. In this case report, the endodontic treatment of a mandibular first and second molar with pyramidal root canal morphology is presented. Keywords: dental malformation, endodontic treatment, root canal morphology, taurodontism

Dens invaginatus in molar teeth is extremely rare. This report presents a case in a right mandibular second molar. The pulp was necrotic and there was a buccal sinus tract associated with the tooth. The dens invaginatus was revealed following a periapical radiograph that also showed a periradicular lesion. Conventional root canal treatment was carried out; a calcium hydroxide paste was used as an intracanal dressing. The root canal space was filled with gutta-percha and sealer using a thermomechanical compaction technique. At follow-up, after 1 year, the tooth was symptom-free and there was radiographic evidence of healing. As a result, endodontic surgery was not required. Keywords: dens invaginatus, molar dens invaginatus, tooth abnormality

Although the most common configuration for mandibular first molars is two roots and three root canals, there are potentially many different combinations. A case of unusual root canal morphology is presented in this report to demonstrate anatomical variations in mandibular molars. Root canal treatment was performed in a mandibular first molar with three separate roots. Examination of the pulp chamber floor revealed four separate canal orifices. However, the working length radiograph showed that the four root canals ended in three distinct foramen (two of the mesial canals were confluent). Cases of three orifices or three independent root canals in the mesial root are not uncommon, but there are very few cases of a first mandibular molar with three separate and divergent roots, which is a rare anatomical configuration. The present report is a reminder of the importance of looking for additional canals and unusual canal morphology, because knowledge of their existence will enable clinicians to treat a case successfully. Keywords: anatomical variation, endodontic treatment, mandibular molar

The aim was to report the diagnosis and successful clinical management of a patient with pathological anatomic variation in a mandibular first molar, caused by internal and external resorption and to evaluate radiographically the long term clinical outcome of the root canal treatment. A case is presented in which a previous caries removal procedure with pulp exposure on a mandibular molar developed into internal resorption of the pulp chamber floor and the distal canal. A preoperative periapical radiograph showed apical external resorption of the molar roots and condensing osteitis associated with the mesial root. Root canal treatment was completed in two visits, with calcium hydroxide used as an interappointment dressing for 1 month. A 36 month followup showed apical root repair and no evidence of periapical bony changes. Keywords: condensing osteitis, external resorption, internal resorption