4. Chemomechanical Disinfection Flashcards
What is meant by shaping the root canal?
Controlled removal of dentine to give a tapering shape that can be sealed throughout its length with a root canal filling.
What are the stages in mechanical preparation of the root canal?
Preparation of tooth Access cavity Straight-line access Initial negotiation Coronal Flaring Working length determination Apical preparation
What is meant by cleaning the root canal?
Removal of organic pulpal debris, microorganisms and toxins.
You clean the main canal, dental tubules, isthmuses and lateral canals.
Why can you not clean a root canal by mechanical means alone?
Must use chemical means as well because there is lateral canals, fin like extensions and webbing between canals.
What are the objectives of using irrigants during root canal treatment?
To disinfect root canal Dissolve organic debris Flush out debris Lubricate root canal instruments Remove endodontic smear layer
What equipment do you use to irrigate a canal?
Luer lock syringe
27 gauge endodontic-tipped needle
What is the action of sodium hypochlorite?
Antimicrobial
Dissolves pulp remnants and collagen
Dissolves necrotic & vital tissue (only irrigant to do this)
Helps disrupt smear layer by acting on organic component
What concentration of Sodium Hypochlorite (NaOCl) is used?
Between 0.5 and 6%
Why must you be careful not to get sodium hypochlorite into the patients mouth or around their face?
Unpleasant taste
Toxicity
*Always ensure dental dam is well sealed
What concentration of EDTA is used?
17%
What is EDTA?
Ethylenediaminetetraacetic Acid.
A chelating agent that is capable of removing the smear layer when used with NaOCl.
How long should you use EDTA for?
1 minute contact time necessary
What is chlorhexidine digluconate?
Positively charged
Lipophilic
Hydrophobic
What does chlorhexidine digluconate do to individual cells?
Interacts with phospholipids a lipopolysaccharides on the bacterial cell membrane.
Also alters the cells osmotic equilibrium.
What properties does chlorhexidine digluconate have?
Antibacterial activity
Anti fungal activity (less than NaOCl)
Somewhat active against biofilms but unable to disrupt them.
Why must you clean the canal of CHX before you irrigate with NaOCl?
Interaction of CHX and NaOCl produces parachloroaniline.
This substance is cytotoxic and carcinogenic.
It also has uncertain bioavailability.
Once canal preparation is complete, the canal should be irrigated with…
1x syringe sodium hypochlorite
1x syringe EDTA/citric acid
1x syringe sodium hypochlorite
What is the purpose of intra-canal medicaments?
Placed in root canal between treatment appointments in an attempt to destroy microorganisms and prevent reinfection.
Reduce inflammation & exudate.
Control of root resorption.
How do you decide if you will complete the treatment in a single visit or multi-visits?
Case-by-case basis
Vital cases often suitable for single visits
Non-vital cases are more complex so an inter-appointment dressing will be necessary
What inter-appointment medicaments are available?
Anti-microbial paste
Non-setting calcium hydroxide
What is anti-microbial paste?
Paste containing corticosteroid & tetracycline
Can aid in reduction of pulpal inflammation
Used in management of ‘hot pulp’
Can facilitate follow up Rx
Effective for 5-7 days
What is the pH of non-setting Calcium Hydroxide?
12.5
What are the actions of non-setting calcium hydroxide?
Prolonged antibacterial activity
Hydrolysis of lipopolysaccharide thus reducing its inflammatory potential
Removes tissue debris
Treatment for 7 days
What materials can be used for an inter-appointment temporary dressing?
Cavit
IRM
Polycarboxylate cements
Glass ionomer cements
