Endodontic Education from Sendoline

Frequently Asked Questions

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What is root canal patency?

This is a concept that is often over complicated. Put simply, root canal patency is a method of preventing debris from building up and blocking the apical parts of the root canal system. Essentially, if you establish your working length with a size 8 or size 10 file, then after every subsequent hand file or rotary file you should return to that working length and ideally fractionally beyond that length with the 8 or 10 file to ensure that the canal remains free of debris. 

Frequent irrigation will also help to maintain patency.

Loss of patency has been cited as predisposing failure of root canal treatments (Ng 2009).

Is this internal or external resorption. Should I try to root fill it?

This would appear to be external resorption

The prognosis for this tooth is very poor. If the resorption has started to have an effect on the pulp then root treatment would alleviate symptoms. However the long-term restoration of this tooth would be very unpredictable and so, on balance the benefit of root treating it would appear limited. 

What is the best way to find root canals in a molar?

To find root canals efficiently you will need several things

  • A knowledge of the normal anatomy
  • An awareness of common variations
  • Magnification and ideally enhanced lighting
  • Patience!

MORE INFORMATION - Sign up to see our guide on locating root canals. 

What is the best way to use EDTA?

EDTA comes in two forms, gels and liquids.

The gels (Fileze, Glyde, RC Prep) are useful in cases with very narrow canals to help to lubricate files and reamers. Sadly they do not help “open up” sclerosed canals – they are of no benefit if left in the canal as a dressing.

The gels should not be used together with Sodium hypochlorite – the two chemicals will simply neutralise each other. Use the gels to help instrument the canals and then once you have established a good guide path rinse out the gel and use hypochlorite as your irrigant.

Liquid EDTA (eg Nordiska 17% EDTA) is used after shaping the canal. It removes the smear layer from the walls of the canal, allowing greater penetration of sodium hypochlorite.

The use of EDTA in this manner has been linked to improved endodontic outcomes (Ng 2011)

What is the best irrigant for root canals?

Sodium Hypochlorite remains the irrigant of choice for the majority of endodontists. 91% of US and 94% of Australian endodontists use Sodium Hypochlorite as their first choice irrigant. (Dutner et al 2011)

Hypochlorite is primarily used for its tissue dissolving and antimicrobial properties. A 3% concentration provides a good balance between these two important properties. Many endodontists will activate the solution either ultrasonically or using endosonic devices.

A common irrigation regime uses hypochlorite throughout the procedure and then a 17% solution of EDTA for 60 seconds, followed by further irrigation with sodium hypochlorite activated with ultrasonics.

MORE INFORMATION - Sign up to see our guide to root canal irrigation. 

What is the best way to remove old GP?

Old GP points can be removed in several ways.

My favourite way is to use a braiding technique. Use 3 size 10 or 15 files. Each one is passed down a different side of the old gp point.  Then the files are twisted around each other trapping the GP point. All three files are then withdrawn, pulling out the GP point.

If this doesn’t work then I use the Sendoline GPR files to mechanically remove the old filling material.

MORE INFORMATION - Sign up to see our guide to removing GP 

How does the size of the periapical lesion relate to the success rate of a root filling?

There is no hard and fast rule to this.

Evidence shows that the presence of an apical radiographic radiolucency reduces the success rate of endodontics. 

Ricucci et al (2011) suggested that teeth, with no apical area had an 89% success rate, when treated by an endodontists. Teeth with an area of less than 5mm = 86%. 

Where the apical area was more than 5mm in diameter, the success rate dropped to 78%.

There are exceptions to this rule of course. This very large apical area shows good healing at six months.

Should I re-root fill this tooth before I place my crown? It has been heavily restored and somebody has tried to root fill it but couldn’t locate the canals. The patient wants to improve the appearance of the tooth – Should I root fill it before I crown it?

There appears to be some widening of the periapical ligament distally. If a previous attempt at root treatment has been made, then it is likely that this tooth will be non-vital.

It would be sensible to re-open the access and try to locate the canals under magnification before placing a definitive crown onto this tooth. If it is not possible to find the canals then referral to an endodontist might be the best option.

MORE INFORMATION : Sign up to See our “guide to finding root canals”

What success rates should I quote to my patient?

The studies on endodontic outcomes all show a trend. Initial treatments are more successful than re-treatments, which in turn tend to be more successful in the long term than surgical endodontics.

Studies by Friedman and Mor in 2004 suggested success rates of 92-98% for initial treatments.

More recent studies on endodontics performed in general practice in the UK suggested a success rate of 74% (Lumley et al 2008) and in the USA a success rate of 71% was suggested by (Berstein et al 2012).

So it would seem sensible to quote success rates of 70-75% for endodontics performed in general practice.

MORE INFORMATION -  Sign up to See our article on “factors influencing success” for more details.