Frequently asked questions 2

Can the files be used for the same patient, on the same tooth for the second time/visit?

In theory yes, but because of the reduction in resistance to cyclic fatigue I do not recommend this. What I do is try to prepare all the canals to the same size and if I want to do more at the next appointment, then use the next file in the sequence which is new from the sterilised pack.

Does anyone warn the patient of the possibility of file fracture prior to RCT and risk of hypochlorite accident? What are the legal issues involved if we do not inform but it happened?

The law and your code of conduct require an informed consent. This includes a financial informed consent. There should be a warning about any “material risks” - A significant potential for harm that a reasonable person would want to consider when deciding about undergoing a medical or surgical treatment.

Can antibiotics help in case of extrusion of NaOCL?

This is a controversial subject, and they may have some use if infected debris is extruded during treatment. In general, I do not recommend antibiotics in hypochlorite accident cases. But it is a clinical case dependent decision.

 If there is a sodium hypochlorite accident, would you see a difference in the colour of the tissues straight away?

There is usually very little change in colour of the gingival tissues, the inflammation is usually deeper, the patient usually reports a burning sensation during irrigation and there is commonly bleeding from the root canal.

 What are the success rates for over extruded GP vs. underfilled GP?

Ng et al 2011

Short root fillings in primary root treatments 74.3%  success. Rerct cases 64.8% success

Long root fillings in primary treatments 67.1% success. Rerct cases 61.5% success

Flush root fillings in primary treatments 85.8% success. Rerct cases 84.6% success

 What do you do if there is a perforation at the furcation level?

Assuming the perforation is small enough to repair I recommend repairing these immediately using an MTA or Bioceramic product. That way you can assess the set of the material at the next visit.

Is Thermafil a good technique for obturation?

Any obturation technique has a learning curve and due to carrier based obturation being a very quick and efficient way to fill a canal, it does have it challenges. I have used carriers to fill canal before, but due to the diverse cases I treat do not use this technique routinely. If you get good results using carrier based obturation, then keep doing what works for you.

What is the role of trichloroacetic acid in the case you mentioned?

Trichloroacetic acid is used to remove resorbing tissue present in external cervical resorption cases. It removes tissue and coagulates it to prevent haemorrhage.

Any other irrigating solution beside hypochlorite, such as chlorhexidine solution?

Sodium hypochlorite is antibacterial due to its high Ph and production of chloramines. It also produces hypochlorous acid and this dissolves tissue which is food for bacteria. So, it is the only irrigant that accomplishes both aims. Removal of bacteria and removal of tissue. EDTA supplements sodium hypochlorite by removing the inorganic smear layer (which sodium hypochlorite does not do).

Other irrigants like chlorhexidine and hydrogen peroxide have no tissue dissolving property and therefore do not dissolve the bacterial biofilms present on the wall of root canals. Therefore, they need to be supplemented with sodium hypochlorite.

Chlorhexidine can be used after sodium hypochlorite, and the canal is flushed prior to its use. Mixing the two irrigants creates a brown precipitate which is difficult to remove.

Regarding the management of the open apex, dens evaginatus case:  1. What % NaOCl would you use? 2. What long-term dressing would you use if the decision was to extirpate and extract in 6 - 12 months’ time for orthodontic treatment? 3. Is a pre-mixed Ca (OH)2 paste unfavourable c.f. mixing your own from Ca (OH)2 powder to achieve a thicker consistency?

  1. I use the same percentage as normal if I am confident, I won’t extrude it. Generally, if you are careful extrusion does not occur.
  2. Calcium hydroxide has the best evidence when used as a long-term dressing, so this is my preference.
  3. I like to use the Ultracal pre-mixed paste for this, and carefully inject this into the canal using a Navi tip. The powder and water mix is also an option if you have this.

When assessing a radiograph, what degree of periapical changes would constitute a basis to make a diagnosis of irreversible pulpal disease -does the size of the periapical radiolucency matter? If a periapical radiolucency is present without other signs and symptoms, what should the management approach be?

Diagnosing irreversible pulpal disease is a clinical decision based on many factors, a radiograph is just one of them. The presence of a radiolucency is often a sign of pulpal disease, but there are more tests required to diagnose pulpal disease. Vitality testing, patient history and percussion, palpation tests are important. Many of the symptomatic irreversible pulpitis cases have no signs of apical disease clinically or radiographically and then the use of temperature sensitivity plays a big role in diagnosis. If in doubt get the patient back another day and reassess when the pain changes.