ENDO, 03/2007

With the rapid development of laser technology, lasers with a wide range of characteristics are now available and being used in various fields of dentistry. It is known that endodontic quality is low worldwide (on average 30% to 40% of root filled teeth are associated with apical periodontitis). The major reason for endodontic failure is insufficient disinfection/sterilisation of the root canal space. The question is whether there is a role for lasers as physical disinfection of the root canal, alongside or instead of chemical disinfection with irrigants such as sodium hypochlorite. On the basis of present-day scientific literature it is concluded that: (1) bactericidal effects have been demonstrated with lasers; (2) current lasers are to be considered as adjuncts to root canal irrigants; and (3) current lasers cannot yet replace sodium hypochlorite as the gold standard. Keywords: bactericidal, disinfection, endodontics, laser, root canal

Microbial biofilms are clusters of microorganisms immobilised on a surface or an interface, enveloped in a slimy matrix of their own creation. In infected root canals, microbial biofilms are formed on hard tissue surfaces of the root canal system. Infection of the root canal system is the cause of apical periodontitis, and complete elimination of the infection is the ultimate goal of root canal treatment. However, this aim is quite difficult, if not impossible, to achieve, due to not only the complexity of the root canal system, which offers inaccessible niches for microorganisms, but also the fact that there are protective advantages in residing in biofilms. Microorganisms in biofilms are more resistant to antimicrobial regimes than their counterparts in planktonic form. A good understanding of the distinctive features of a microbial biofilm, particularly in root canal infection, is important to enable development of techniques to eliminate the microbial biofilm, and as a result, (post-treatment) apical periodontitis. In the following review, the definition, main features and significance of a microbial biofilm, and its relevance to root canal infection will be discussed. Keywords: biofilm, endodontic, root canal infection

This paper reviews the ways in which traumatised teeth may become discoloured. The literature was searched using the PubMed database with the following terms: dental trauma, tooth discolouration, pulp necrosis, tooth staining. The search was limited to articles in the English language. A manual search using references from this source followed. Although all abstracts were read in full, this is not intended as a systematic review. Little has been written in endodontic texts; much has been said about bleaching and other means of treating discoloured teeth, which is beyond the scope of this paper. Keywords: calcific metamorphosis, pulp haemorrhage, pulp necrosis, resorption, tooth staining

In the last decade, rotary nickel-titanium (NiTi) instruments have become increasingly popular for preparing root canals. Therefore, the aim of the present article is to review the literature on in vitro evaluation of rotary root canal instruments. The focus is on studies of shaping and cleaning ability, safety and working time. The use of NiTi instruments produced sufficient cleanliness with acceptable preservation of the root canal anatomy. Both centring ability and decreased straightening of root canals is superior with NiTi instruments compared with the manual technique using stainless steel instruments. However, the apical part of the root canal showed similar or fewer remnants of debris after manual instrumentation. These aspects highlight the demand for an efficient irrigation combined with mechanical preparation of the root canal. Additionally, the use of a torque-controlled device and constant speed control is recommended to reduce the risk of instrument fractures. It can be concluded that appropriate handling of engine-driven NiTi systems in combination with sufficient (antimicrobial) irrigation facilitates successful endodontic treatment. Keywords: instrument separation, root canal preparation, rotary nickel-titanium instruments, shaping ability, transportation

This report describes a rare palato-radicular groove in a maxillary lateral incisor with an accessory root and an atypical root canal. Failure to identify the presence of the palatal groove allowed infection to persist, which led to palatal swelling and labial fistula. During endodontic retreatment of the infected root canal, an accessory root with a second root canal was detected. Owing to the extent of the circumferential bone loss and the atypical root canal, the second root was resected. Histological analysis of the resected root suggested there was reparative dentine in the deep groove and several accessory canals. The structure of the reparative dentine was irregular. In the apical third of the resected root, the canal was oval with a wide slit-type aperture. It was possible that the combination of the deep groove and the accessory canals with the atypical communication to the periodontal ligament was the reason for retrograde pulp inflammation and pulp necrosis. Rapid healing after surgical treatment was observed. At the 6-month follow-up examination, the patient was symptom-free. No swelling or exudation was present. Radiographic investigation of the lateral bone defect showed the beginning of ossification and healing. Keywords: endodontic-periodontal lesion, ledges, palato-radicular groove, radicular palatal groove