24 April 2017
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Endodontics Revision Part 1

Endodontics Revision Part 1

 

This article aims to provide some endodontics revision and practical tips for those of us who struggle with root canal treatment. If you don’t then you’re definitely lying!

Quick recap, what are the aims of endodontic treatment?

  • To reduce bacterial load in root canals,
  • Removal of infected pulp tissue,
  • Three dimensional hermetic seal of the root canal system.

Diagnosis

First of all, you have to determine that the tooth you are about to remove the pulp from is the correct tooth. And before you subject any tooth to this irreversible procedure you need to have the right diagnosis. See our articles on taking a pain history and vitality testing for more pointers!

Radiographic Examination.

A good quality peri-apical of the tooth in question is essential as a pre-requisite. Using a film holder, take a PA with a paralleling technique and then:

  • Look for PA pathology, this should be part of your diagnosis.
  • Look for the pulp chamber, and follow into the root canals to check for patency.
  • Look for number of, and deviations in the root.
  • Measure the distance between the cusp and furcation. (To help orientate you when you are accessing the tooth to avoid perforations)
  • Measure the ESTIMATED working length from a stable reference point (usually a cusp tip, it might help to flatten the cusp with a diamond bur to make the reference point a bit more consistent.

Access

Before we even begin to talk about touching to the tooth, it is important to emphasise the importance of magnification and illumination in Endodontics. If you have not already, it is strongly advised to invest in a pair of dental loupes and a light which will improve the quality of your dental work.

Access Cavities

Before you access a tooth, it’s good to have an idea of where the canals are going to be. Head over to the Endodontic Access Cavities article for a table of access cavities for each tooth.

When we access, we’re looking for straight line access up to the first curve of the root canal, so that we can get straight up and down filing action in the root canal.

Having a rough idea can help you get started, but there are common problems that we all struggle with. When am I in the pulp chamber? Am I going to perforate? Have I found all the canals?

Pulp Chamber and Perforating

Colour

One thing to know is that the dentine of the roof of the pulp chamber and the dentine of the floor of the pulp chamber have a distinctly different colours.
The roof of the pulp chamber is a dull, yellow colour that is similar to the dentine in your normal cavities. Once you get to the floor of the chamber, it becomes glossy and white. Look for this difference when you are cutting your cavities to avoid drilling too far. Also, as above, measure the distance on the radiograph AND measure the length of your bur as another guide to not perforating.

Road Map

The floor of the pulp chamber usually has a grey/black ‘road map’ – these are developmental grooves where the pulp tissue rested. The significance of this ‘road map’ is that it may help to guide you when looking for canals. Follow the road maps and they will give you clues to the location of canals. Therefore, it is important when removing the roof of your pulp chamber not to damage the floor of the pulp chamber, as you will damage this very useful biological map.

Use the CEJ

Use your straight probe around the CEJ of the tooth to determine it’s angulation, especially under a crown. This will help to angulate your bur to make sure you are drilling in the direction of the pulp chamber rather than through the side of the tooth!

Finding the Canals

Probing around the CEJ can give you even more vital information.

  • The shape of the pulp chamber mirrors the shape of the CEJ, only smaller! Remember this, and it will help you locate your canals
  • The canal orifices can be found at the junction between the floor and the wall of the chamber.
  • It is also useful to use a sharp DG16 endodontic explorer when looking for canals, instead of just a standard dental probe.
  • Look for symmetry in the location of the canals, for example, if you find a distal canal that is off to the buccal side in a lower 6, look for a separate canal further towards the lingual. If, on the other hand, the canal is bang in the middle, you can stop there knowing that you have all the canals of the distal root!

Knowing how many canals you should be looking for is useful too, jump across to the Endodontic Access Cavities article again for more information.

Stay tuned for part 2 when we cover shaping and obturating!