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Modern endodontic principles part 3: preparation

From Volume 42, Issue 9, November 2015 | Pages 810-822

Authors

James Darcey

BDS, MSc, MDPH, MFGDP, MEndo, FDS(Rest Dent)

Consultant and Honorary Clinical Lecturer in Restorative Dentistry, University Dental Hospital of Manchester

Articles by James Darcey

Carly Taylor

BDS, MSc, MFGDP, FHEA

Clinical Lecturer/Honorary Specialty Registrar in Restorative Dentistry, Dental School, University of Manchester

Articles by Carly Taylor

Reza Vahid Roudsari

DDS, MFDS, MSc, PGCert(OMFS)

Clinical Lecturer/Honorary Specialty Registrar in Restorative Dentistry, Dental School, University of Manchester

Articles by Reza Vahid Roudsari

Sarra Jawad

BDS, BSc, MFDS

Specialty Registrar/Honorary Clinical Lecturer in Restorative Dentistry, University Dental Hospital of Manchester

Articles by Sarra Jawad

Mark Hunter

BDS MSc

Registered Endodontic Specialist, simplyendo, Altrincham, Postgraduate Clinical Teaching Fellow, Dental School, University of Manchester, Higher Cambridge Street, Manchester, M15 6FH, UK

Articles by Mark Hunter

Abstract

The purpose of instrumentation is to facilitate irrigation and allow controlled obturation. This article will revisit methods of instrumentation of the root canal system with consideration given to length determination, apical preparation and the concept of patency filing. It will discuss hand instrumentation and rotary preparation looking at emerging technology such as reciprocating systems and the self-adjusting file.

CPD/Clinical Relevance: Mechanical preparation of the root canal system is of fundamental importance in achieving success, creating a more easily managed environment from a biological perspective.

Article

The objectives of mechanical preparation are two-fold:

The majority of micro-organisms are in the coronal portion of the canal and pulp chamber.4 Thus, whatever instruments are used, a crown down approach and only initial scouting of the canal prior to working length determination is sensible. This technique involves shaping the canal from the coronal aspect first and progressively working more apically with smaller diameter instruments5 (Figure 1). Such an approach:

Traditionally, Gates Glidden (GG) instruments would be used for the crown down procedure but many rotary filing systems now have orifice shapers to begin the preparation (Figure 2). If clinicians elect to use GGs it is wise to remember a Size 6 GG has an apical diameter of 1.5 mm (ISO 150), with sizes stepping down in 0.2 mm increments to a Size 1 GG at 0.50 mm (ISO 50). As such, even the smallest of GGs can be very destructive if used carelessly. Avoid using sizes above GG 3 (0.90 mm: ISO 90). Whatever instruments are used, caution must be taken with regard to the furcation region, the instruments being used away from the furcation (anti-curvature filing6). Despite the aforementioned advantages, it is easier to create blockages and ledges with an aggressive or careless crown down approach, thus highlighting the importance of recapitulation.

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