ENDO, 01/2008

The unequivocal role of microorganisms in the aetiology of apical periodontitis has been well established. As a consequence, successful treatment of this disease is contingent upon effective elimination or maximal reduction of the involved microbiota. There are at least two major aspects of endodontic infection that need to be well understood for establishing effective therapeutic protocols: the composition of the endodontic microbiota associated with the different forms of apical periodontitis and different types of infection (i.e. which are the main candidate pathogens); and the patterns of microbial colonisation within the root canal system (i.e. how they are distributed along the infected tissues). This review focuses on the current knowledge of these two aspects. Proper interpretation and clinical application of this information has the potential to be translated into improvements in quality and predictability of the treatment offered to patients. Keywords: apical periodontitis, endodontic infection, endodontic pathogens, root canal treatment

Hard tissue fractures seem to occur more often in root canal treated compared with vital teeth. This phenomenon may be explained by three contributing factors: 1) the loss of tooth vitality and thus resulting in decreased sensitivity to occluding forces; 2) the reduction in total dentine mass by pulp access and dowel preparation; and 3) the chemical weakening of dentine induced by the agents used for root canal disinfection. In this literature review, the last of these issues is discussed. Structural and mechanical properties of normal and age-altered dentine are described, and some key mechanical parameters of dentine presented. Finally, chemical effects of current topical root canal disinfectants on dentine structure and mechanical integrity are discussed. Keywords: Ca(OH)2, dentine, EDTA, hypochlorite, root canal treatment

This article illustrates the conceptual basis and the operative procedures of the zone technique and explains the specific instruments used in each phase. The zone technique defines two regions of the root canal: the coronal zone (the area above the curvature of the canal) and the apical zone (the area below the curvature). Whether the root canal possesses a significant curvature must first be determined. The instruments and procedures are separated into four different steps. In the first phase, the distance of the curvature from the apex is determined. The area above the curvature of the canal (coronal zone) is then shaped with NiTi rotary flare instruments. In the third phase, a stepback sequence is used to enlarge the area below the curvature (apical zone) with ISO size (#)20 taper .02, #25 .02, #25 .04 and #25 .06 NiTi rotary instruments. During the final phase, finishing #30 .06 or #35 .06 NiTi rotary instruments are used to shape the apical third of the canals. Keywords: curved root canal, NiTi instruments, root canal preparation, shaping

This paper intends to review the Thermafil® system (Dentsply Maillefer, Konstanz, Germany) from the practitioner's point of view. A brief introduction to Thermafil and description of the system is followed by a discussion of the advantages and disadvantages of this filling technique, based on a review of the pertinent literature, and concludes with two case reports. Keywords: extrusion, gutta-percha carrier system, leakage, root canal filling, thermoplasticised gutta-percha

Infections of endodontic origin rarely cause neural injury. This article presents a case of paraesthesia caused by endodontic infection of the left mandibular molar associated with large periradicular radiolucency. The sensory disturbance disappeared one week after chemo-mechanical preparation and intracanal dressing with a calcium hydroxide paste in camphorated paramonochlorophenol and glycerin. Complete healing of the periradicular tissues was radiographically observed after 24 months. Keywords: endodontic infection, inferior alveolar nerve, paraesthesia