Chemomechanical Disinfection

Question 1

What is the overview of chemomechanical disinfection

Answer 1

Use of mechanical technique to deride the interior of a canal coupled with chemical disinfection to fully remove canal contents

Question 2

What are the design objectives of chemomechanical disinfection?

Answer 2

To create a continuously tapering funnel shape

To maintain the apical foramen in the original position

To keep the apical opening as small as possible

Question 3

How large should apical prep really be?

Answer 3

At least ISO size 25, some advocate 30 or larger

Question 4

Give some ideal properties of an irritant

Answer 4

Kills planktonic and biofilm microbes

Detaches biofilm

Non toxic to periapical tissue, also non allergenic

Improve cutting of dentine and reduce friction

Does not weaken dentin

Question 5

What is typically used for irrigation? And what concentration of it should be used?

Answer 5

NaOCl - sodium hypochlorite

0.5-6% 3% is used in the dental school

Question 6

What type of needle is used for irrigation in endodontics? Why?

How do we ensure the material reaches the bottom of the canal with a safe needle?

Answer 6

Safe needles - side vented

Open ended needles may spray irritant out of the foramen with force and cause significant tissue damage

Ensure it reaches all areas with an endoactivator, this agitates the material through vibration to ensure it reaches all areas.

Question 7

Are there any risks associated with NaOCl?

Answer 7

It dissolves organic content and dentine has a high organic content

The higher the concentration of NaOCl, the greater the decrease in dentine modulus of elasticity and felxural strength

Question 8

What is smear layer and how will this affect RCT and CMD? How is it removed? does this interfere with NaOCl?

Answer 8

Smear layer is created when cutting dentine with the files, this can inhibit the chemical disinfection of the canal. it is a mix of organic and inorganic debris within the canal.

It is removed through use of 17% EDTA (1 minute) and use of sonic or ultrasonic irrigation

Can’t have both irritants present in the tooth at the same time, must remove irritant, dry, then place new irrigant

Question 9

How should the canal be finally irrigated after all canal shaping has been carried out?

Answer 9

1- 3% NAOCl throughout instrumentation and at least 30mL after instrumentation complete with MDI at least 10 mins prior to obturation

2- 17% EDTA for 1 minute penultimate rinse

3- 3% NaOCl final Rinse

Dry canal with paper points between rinses