Root canal preparation with reciprocating instruments - A literature review and clinical application

It is well described that the presence of microbial flora in the pulp space of the tooth, and the inability of the immune system to remove these pathogens, are the major sources of peri-apical and radicular inflam-mation.1 Eradication of these pathogens from the pulp and root canal space by means of cleaning, shaping, disinfecting and complete obturation is necessary to safeguard the health of the periodontal tissues from endodontic infection and subsequent breakdown.2,3 The basic objectives of cleaning and shaping of root canals include: (1) removal of all infected soft and hard tissues; (2) creating space for delivery of disinfectants and medicaments to the apical part of the canal; (3) facilitating three dimensional obturation and (4) preservation of radicular structures.4 Even modern endodontic file systems leave untouched areas on the root canal walls after preparation and show compaction of hard tissue debris.5 This debris consists of pulp tissue remnants, bacteria and dentine chips of which most is found in the apical part of the prepared root canal system.6 Aiming for a centred preparation that corresponds to the original canal anatomy accompanied by the lowest amount of canal transportation, especially in middle and apical parts of curved canals, will result in the most favourable post instrumented canal shape. The four optimal canal shaping objectives are: (1) to have a tapered funnel from orifice to apex, (2) maintenance of original anatomical canal pathway, (3) apical foramen position should remain constant and (4) leaving the apical opening as small as possible.2,7