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Authors: Dr. Mandar Pimprikar

Q.1- What is smear layer in Endodontics and what is its clinical significance?
  1. It is a layer as a result of rasping action of any endodontic file.
  2. Any metallic instrument (rotating or reciprocating in the root canal) it will allow smear layer to form on the root canal walls.
  3. Smear layer contains organic and inorganic components like pulp tissue, proteins, bacteria & dentinal chips/ dentinal debris.
  4. The smear layer is usually 1 to 2 micro meter thick to 5 micro meter; sometimes may get extended into the lateral canals and dentinal tubules to for a smear plug.
Clinical significance:

There has been a direct correlation between smear layer and success rate in Endodontics for reasons like-

  1. Once the smear layer or smear plug is formed; this will not allow further penetration of the antibacterial NaOCl solution, thereby Leaving that portion of the canal untreated & cause failures.
  2. If the smear layer is left behind; it will also affect the bond strength of the sealer to the dentin.
Q.2- How to remove or avoid smear layer?

I will answer that in sequence:-

Removing smear layer:

As smear layer is predominantly an Inorganic complex mixture; we need a chelating or decalcifying agent.

Most commonly used agents are 17% aqueous EDTA & citric acid.

To remove smear layer during the instrumentation:-

  1. Use NaOCl and 17% aqueous EDTA in alternate sequence. E.g. NaOCl → normal saline →17%EDTA
  2. After complete shaping, use 17% aqueous EDTA for 1 minute - activation is advisable.
Avoiding smear layer formation:

The above-mentioned method is traditional approach towards smear layer removal. The newer approach is that you do not allow the smear layer to form by Using continuous relation concept- Which is a combination of NaOCl (5%) and etidronic acid (9%) ( chlor o quick )used together, does not allow smear layer to form or whatever is formed is dissolved immediately; thereby increasing the penetration of NaOCl. Advantages of continuous chelation over traditional approach is that only one solution is required which will act as antibacterial, tissue solvent, chelating agent, emulsifying agent. This Prevents smear layer and smear plugs and increase the penetration of NaOCl to have a direct impact on “Hard To Reach “ area and have complete disinfection.

Q.3- What is your take on apical patency and what is its role in clinical success?

The use of patency file still remains controversial issue amongst clinicians. This is typically done with 10 number K file which is passively introduced in the canal 1mm past the apical foramen. The step is intentional Achieving and maintaining patency.

Once the patency is achieved, it is maintained by introducing 10 number K file 1 mm beyond the working length. This step helps in taking the irrigating solution into the inaccessible areas as well as apical 1/3rd.

This procedure is important to achieve clinical success.

On the other hand, some clinicians have concerns with the increased extrusion of debris and irrigants resulting into more postoperative pain. The concerns regarding using the patency file are and the Justification to use patency file are.

  1. Apical transportation- using 10 number K file will not alter the apical anatomy.
  2. Extrusion of irrigants & debris- clinically patency file will help maintain the working length and avoid packing of debris in apical 1/3rd.
  3. Apical patency and prognosis- there are no conclusive studies on this but as clinicians we should incorporate apical patency to
  • maintain the working length
  • avoid packing of debris
  • Increased penetration in apical 1/3rd area by the irrigants
Q.4- Can you share some tips on syringe and needle irrigation (manual technique)?

The manual irrigation is typically done with a syringe and needle. Most of the clinicians are still with this traditional method to irrigate the root canal space.

There are few points I would like to mention:-

  1. The syringe used should be preferably 5 ml as this method is of positive pressure irrigation. 5 ml of syringe allows you to irrigate without exerting too much of pressure as compared to 2 ml syringe.
  2. Always use thinnest possible (30) gauge - side vented needles. This will allow you to deposit the irrigating solution close to the working length. The side vent and apically blocked needles will not allow forceful pushing of an irrigant in the peri apical tissues.
  3. While doing irrigation never lock the needle into the canal. The needle should be moved up and down.
  4. Always use palm grip and not the thumb grip.
  5. Lastly label the syringe as in NaOCl to avoid accidents and negligence in the clinic.
If You Have any Question Regarding Endodontics Please feel free to send at: This email address is being protected from spambots. You need JavaScript enabled to view it. or This email address is being protected from spambots. You need JavaScript enabled to view it. . We will give you the answers in any of the upcoming issues of Guident.