Endodontics

Question 0

What is the requirement of a pre operative radiograph before a root canal treatment?

Answer 0

Peri apical radiograph
Tooth being treated centrally located
3-4 mm peri-radicular tissue visible

Question 1

How do you determine what shape an endodontic access cavity to drill?

Answer 1

Judge by the number of pulp horns the tooth has

Canines and premolars have 2 so access should be OVAL
Incisors have 3 so access should be TRIANGLE
Molars can vary

Question 2

How do you create an access cavity for a root canal?

Answer 2

Check on a radiograph the depth from the reference point to the roof of the pulp chamber
Use a tapered fissure bur to create suitable outline into dentine, continue until into the pulp chamber
Apply the rubber dam
Remove the roof of the pulp chamber with a slow speed from the overhang upwards to create a gentle flare
Clear debris with excavator
Irrigate and ensure there is straight line access

Question 3

What is the estimated working length of a canal?

Answer 3

Using a radiograph measure from a reference point to the radiographic apex and take away 1mm

Question 4

What is the corrected working length of a canal?

Answer 4

Once the tooth has been radiographed with the master K file in place you can see if the tip of the file is 1mm back from the apex if not then can adjust the value

Question 5

Which files are used for orifice enlargement?

Answer 5

Hedstrom files

Alternatively you can use gates glidden burs

Question 6

Describe Hedstrom files

Answer 6

They are machined from a round tapered blank by cutting a spiral groove into the shank

They have a sharp blade with aggressive cutting action

Question 7

List the steps involved in orifice enlargement

Answer 7

Size 10K file watch winded to assure canal patency to CWL
Starting with the largest Hedstrom file that will pass 3mm into the orifice a rasping action used circumfrentially
Use progressively smaller filers to widen the canal deeper

Question 8

What is the purpose of orifice enlargement?

Answer 8

To remove infection
Better access to apical 3rd
Better irrigation
Reduce any curvature

Question 9

What are the 3 lengths endodontic files come in?

Answer 9

21mm
25mm
32mm

Question 10

What degree of taper to endodontic files have?

Answer 10

0.02 or 2%

Eg a file that is 0.25mm at the tip will be 0.32mm wider at the top of the cutting part

16 x 0.02 = 0.32 All files have 16mm of cutting length

Question 11

Summarise the modified step back technique

Answer 11

Access cavity
Check patency with 10k
Estimate working length on X-ray then finalise CWL
Orifice enlargement with Hedstrom files
Create apical stop at CWL (k files 2 sizes above first to bind is the master apical file irrigate and recapitulate)
Step back (set each file 1mm less than previous, irrigate, recapitulate with MAF)