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ePaper created 2017-06-15, 09:14:00 | version 1.38.0
| industry Sealer placement in lateral/accessory canals Utilising the Nd:YAP laser Authors: Dr He-Kyong Kang & Dr John Palanci, USA In 1967, Schilder1 had postulated that the final ob- jective of endodontic procedures should be the total three-dimensional filling of the root canals and all ac- cessory canals, in addition to the elimination of all or- ganic debris, bacteria, and bacterial toxin. Therefore, the ability of filling lateral canals has been regarded as a measure of the endodontic treatment quality. Nevertheless, the substantive need for filling lat- eral and accessory canals is still a controversial issue among clinicians. Kasahara et al.2 reported the inci- dence of accessory canals in the maxillary central in- cisors to be over 60%, and Dammaschke et al. showed 79% of molars had lateral/accessory canals.3 Large numbers of lateral/accessory canals exist in the roots, but the frequency of periapical lesions related with these ramifications is not as high as anticipated.4,5 The answers for these clinical observations are still not clarified. The differences in size between main apical Fig. 1: 320 µm (red) and 220 µm (black) laser optic fibres. Fig. 1 26 laser 2 2017 foramen and lateral/accessory foramen might ex- plain why the apical lesions were observed more fre- quently than lateral lesions.3 The amount of bacteria existing in the small ramifications might not be suffi- cient to raise inflammation which can be detectable on radiographs. Occasionally, the lateral lesion is healed without lateral canal filling because simple canal treatment could stop the diffusion of bacterial products from the main canal which might reach peri- odontal ligaments through lateral/accessory canals maintaining vitality.6 However, if periapical lesions originate from bacteria surviving in some spaces derived from lateral canals and irregularities of root canals, such as isthmuses, ramifications, deltas,6–8 then the treatment seems to be particularly chal- lenging for clinicians. Since it is unlikely to kill all pathogens in entire root canals, Buchanan9 suggested that the embedding of remaining bacteria with filling materials can achieve the same results as from complete disinfection in the canal systems. Thermo-plasticised gutta-percha filling techniques have been considered preferable means to achieve this goal due to remarkable fre- quency of lateral canal filling based on case reports and in vitro studies.9–11 Two major concerns for using thermoplastic techniques would be the periodontium damage by temperature increase and overextension of root canal filling materials, especially gutta-percha. The application of lasers in endodontic treatment is an attempt to minimise these potential risks. The investigation of laser applications in endodon- tics was first reported in the early 1970s.12 Among a variety of conceivable uses, most researches empha- sised the efficiency of debridement and the possibility of shaping the root canal by laser.12–14 It seems that the disinfection and cleaning of the root canals would be the most practical use of laser devices in endodontic treatment.12,15–22 The maximum disinfecting effects in