A Guide to Endodontics

So recently, I had a study day on Endodontics, a procedure that can be source of nightmares for many dentists! 

Having limited experience at Dental School (I think I carried out 6 root fillings in total whilst studying!), once we graduate we are expected to be competent in this area of dentistry. 
Whilst a 20 year old patient who required root canal treatment (RCT) on their upper central incisor wouldn't really lead to a sleepness night of worry, endodontic treatment of a molar (which is a very common treatment in practice) would certainly lead to some trepidation!

This study day, led by Dr Rohan Rajasingham, a specialist endodontist, has taught me that there are no shortcuts when it comes to this sort of treatment and the more practice you get, the better and more efficient you will become when providing RCT for your patients. 

Here is a summary of what I took from the day.

What Leads to Successful Endodontic Treatment?

  1. Shaping i.e. the shaping of the root canal system to allow for a placement of a filling material
  2. Debridement: by mechanical and chemical means e.g. irrigants, intracanal medicaments
  3. Obturation i.e. good sealing of the root canal system coronally and apically which prevents recontamination of micro-organisms and their products

Why is there a need for chemical irrigation?

It is virtually impossible to instrument the entire root canal system via mechanical means alone therefore we must use an irrigant to access the complex root anatomy, especially the apical deltas which are most associated with pathogenic bacteria. 

Which irrigant should I use?

The irrigant which has been proved to be the most effective throughout the years is Sodium Hypochloride (3%).
There should be adequate enlargement of the root canal in order to allow the irrigant to reach the apical anatomy and there should be frequent turnover and sufficient volume of the irrigant which should be agitated in order to work most effectively (by means of a hand file or ultrasonic activation).
EDTA can also be used synergistically with sodium hypochloride, as it can dissolve inorganic tissue whilst sodium hypochloride can dissolve organic tissue. 

What is Patency Filing?

The passive movement of a small file (ISO 08-10 K File) <1mm through the apical foramen which is only carried out once the coronal preparation has been completed.
The theory behind doing this is that it may allow irrigants to reach the apical deltas, it helps prevent ledging and transportation and encourages drainage of exudate or pus. 

What is Recapitulation?

This ensures the irrigant is replaced apically. 
Instrumentation leads to dentine mud (saturated irrigant and dentine debris) which can block the canal apically. Therefore it is important to frequently replace the irrigant and place a small K file (08/10) to full length and agitating the fluid. 

Access Cavity Design

This is crucial and should not be rushed! 

The entire roof of the pulp chamber needs to be removed in order to get good vision and tactile access to the entrances of the root canals i.e. Straight Line Access

The access should preserve as much tooth tissue as possible whilst allowing for the above and there should be good resistance form for a temporary restoration.
It also may be prudent to reduce cusps or provide a cuspal-coverage restoration in order to protect the tooth from fracturing between visits. 

MAGNIFICATION is highly recommended, whether it be Loupes or a microscope. This will make your life much easier! 
Safe-end burs e.g. Endo Z, are essential to preventing damage to the pulp floor when removing the roof of the pulp. 
Endodontic ultrasonic tips can be useful when revealing canal entrances or removing calcifications - especially when revealing MB 2 in upper molars, 90% of upper 6s have MB 2 canals!

Determination of Working Length (WL)

WL - length at which each instrument is used in the root canal. This is not necessarily the same as canal length!

This is best determined by an apex locator, estimating from radiographs is not reliable although it is sensible to take a working length radiograph to confirm your reading. 

The WL should be set at 1mm short of the canal length (in more experienced operators this can be reduced to up to 0.25mm short) 

Canal Preparation Techniques

1. Handfiling - Step Back or Crown Down. Crown Down is preferred as this removes the more infected coronal tissue first and allows for deeper penetration of the irrigant. 

2. Protapers - Continuous clockwise rotation of the files. Use of S1, S2, F1 and F2 files (or Sx file to use for coronal flaring). Need to be used with a light brushing motion and needs a glide path. Avoid using in very curved canals as there is high risk of file separation. 
Use up to size 20 K File to scout the canal as the actual size of a S1 file is 0.18mm.
DO NOT use a brushing stroke with finishing files, immediately withdraw the file once it reaches WL in order to prevent over-instrumentation. 

3. Single File Preparation e.g. Recriproc, Wave One - Reciprocating movement of the file. It is not necessary to have a glide path. One file is used to prepare the entire canal.

Having practised with each technique (although at the moment the only technique I use on patients is handfiling), my favourite is the single file system (we tried with Reciproc).

Once you get used to the tactile sensation of the file which feels quite destructive, the procedure is very quick and easy. Whilst the Protaper system is efficient too, it was easy to get the file 'stuck' in the canal and I had to reverse it back out quite often!

A one file system is also advantageous as often I will use up to 10 different files on a patient, so there is a lot of waste! Despite the initial cost of the handpiece and the single files being more expensive than hand files, in the long term these systems could save money as well as time!

An endodontic training tooth which I prepared using the Protaper rotary system. 

Obturation Techniques

Remember you need to create an Apical Stop in order to prevent the root filling extruding out of the apex. Protapers, Reciproc and Wave One all have their corresponding sized Gutta Percha Points. 
All techniques should use a sealer in combination with the gutta percha e.g. Sealapex

1. Lateral Condensation - the most common technique in general practice. The use of a master cone with accessory gutta percha points condensed with finger spreaders. Once placed, a warm plugger should be used to encourage spread of the GP into lateral canals. 

2. System B - Packing of thermafil GP at the apex much like a GP pellet. To be used in combination with Obtura.

3. Obtura - Thermafil GP used more coronally. The GP should be backfilled against the GP placed with System B.

Please click to see more information about Reciproc, Wave One, Protaper, System B and Obtura

I hope you have found this guide useful! Have you used Reciproc, Wave One or the Protaper system? What were your thoughts them? I'd love to hear your views in the comments below!

Why not take a look at my other Clinical Guide posts?

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  3. The technical demands and level of precision required for successful performance of Endodontic procedures is achieved by careful manipulation of instruments and by strict adherence to biological and mechanical principles. Although the armamentarium of endodontics has grown in complexity over the past 30 years, yet, the basic instruments used today are not much different from those used at the turn of the century. This handbook will discuss about the various instruments used during endodontic treatment.
    A Concise Handbook of Instruments used in Endodontics


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