Rationale for chemo-mechanical debridement

1. Rationale for chemo-mechanical debridement Dr LM NaidooBDS, MSc Dent, M Dent Pros (Wits) 28/02/2011

2. Shilder 1974 “Unlike funnels of simple geometric design, this root canal preparation should occupy not only three planes, but as many planes as are presented by the root canal under treatment…” Stace Linde 2003

3. Round files in root canals Not All Canals Are Round Stace Linde 2003

4. Round files in root canals Grande et al. 2007

5. Objectives of chemo-mechanical debridement • Remove organic material and inorganic debris • Disinfect as much of the canal system as possible • Allow for ease of cleaning and shaping of the canals in preparation for obturation

6. Dentinal walls following instrumentation Stace Linde 2003

7. Shilder 1974 “Unlike funnels of simple geometric design, this root canal preparation should occupy not only three planes, but as many planes as are presented by the root canal under treatment…” Stace Linde 2003

8. Principles of Irrigation • Only irrigate under usage of rubber dam • Irrigate following the use of each file • Canal access endeavours should allow for the irrigation tip to lie at two thirds of the radiographic working length.

9. Principles of Irrigation • The needle tip should not bind to the walls of the canal • Allow for adequate time in the canal system for optimal action • Always check for leakage around the protected areas.

10. Types of Irrigants Unknown source

11. Contemporary Irrigants • NaOCl (Sodium hypochlorite) • Dissolves organic content • Bacteriostatic and bactericidal • Spectrum of action includes fungi • Effective at low concentrations • Able to penetrate up to 300 microns into the dentinal tubules • Harmful to the periapical tissues if extruded beyond the apex.

12. Contemporary Irrigants • 2. Sterile water and or Distilled water • Weak evidence that it is bacteriostatic • Does not adequately dissolve organic contents • Less harmful if extruded beyond the apex.

13. Contemporary Irrigants • 3. Local anaesthetic • Weak evidence that it is bacteriostatic • Does not dissolve organic contents • Penetration into dentinal tubules? • Less harmful if extruded beyond the apex.

14. Contemporary Irrigants • 4. Hydrogen peroxide • Bacteriostatic and bactericidal • Weak action against fungi • Dissolves organic contents? • Penetration into dentinal tubules? • Toxic if extruded beyond the apex

15. Contemporary Irrigants • 5. Chlorhexidine • Bacteriostatic and bactericidal • Very weak action against fungi • Dissolves organic contents? • Penetration into dentinal tubules? • Less toxic to periapical tissues compared with NaOCl

16. International Standards • American Association of Endodontists (2004)- Not comprehensive with non-surgical endodontics • European Society of Endodontology (1994)- Predated Rotary Instrumentation. • (2006)- More comprehensive • ISO- Standards based on evidence-based research

17. Irrigant choice amongst SA clinicians

18. The optimal irrigant In terms of antimicrobial and tissue-dissolving properties there is no other current irrigant besides NaOCl which can optimally achieve the objectives of chemo-mechanical debridement The current available evidence is suggestive that a concentration of >1% NaOCl is not required

19. Dentinal walls following instrumentation Stace Linde 2003

20. The effect of chelating agents.. Stace Linde 2003

21. NaOCl + EDTA • No evidence to support any claims for the • antimicrobial action of EDTA • Partial inhibition of the action of NaOCl Grawehr et al. 2003; Zehnder et al. 2005 Stace Linde 2003

22. NaOCl + Chlorhexidine The combination of 2% NaOCl and 0.2% chlorhexidine digluconate produced better antimicrobial results compared to their separate use. (Kuruvilla and Kamanth 1998) • A dense brown substance is the resultant • A chemically unstable material produced • Marcheson et al. 2007; Cathro 2004

23. Designs of needle tips