Rationale for chemo-mechanical debridement

Dr LM Naidoo BDS, MSc Dent, M Dent Pros (Wits)

28/02/2011

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

Round files in root canals

Not All Canals Are Round

Stace Linde 2003

Grande et al. 2007

Round files in root canals

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

Dentinal walls following instrumentation

Stace Linde 2003

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

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.

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.

Types of Irrigants

Unknown source

Contemporary Irrigants1.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.

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.

Contemporary Irrigants3. Local anaesthetic

• Weak evidence that it is bacteriostatic• Does not dissolve organic contents• Penetration into dentinal tubules?• Less harmful if extruded beyond the

apex.

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

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

• 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

International Standards

Irrigant Selection Percentage of respondents

- Sodium hypochlorite (NaOCl)

- EDTA- Saline- Hydrogen peroxide- Other: Chlorhexidine Local anaesthetic Water

91 40 6 14 6 6 2

Irrigant choice amongst SA clinicians

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

Dentinal walls following instrumentation

Stace Linde 2003

The effect of chelating agents..

Stace Linde 2003

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

NaOCl + ChlorhexidineThe 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

Designs of needle tips