What is smear layer Endodontics?

The smear layer is a physical barrier that decreases the penetration of disinfecting agents into dentinal tubules, and consequently, their efficacy. The most important cause of endodontic failure is the residual microorganisms that are harboured within the root canal system and hard-to-reach areas.

Should we remove smear layer?

Removing the smear layer allows for more cleaning and disinfecting root canal walls and better adaptation of root canal filling materials. However, the presence of smear layer can act as a seal to the dentinal tubules and minimize the ability of bacteria and its toxins from penetrating the dentinal tubules.

Does acid etch remove smear layer?

Acid-etching for as little as 5 seconds removes much of the smear layer and exposes the orifices of dentinal tubules.

Is the smear layer inorganic?

The smear layer, comprising both organic and inorganic components, is found on the root canal walls after endodontic instrumentation. It is composed largely of particulate dentine debris created by endodontic instruments during root canal preparation but also contains pulpal remnants and microorganisms.

What happens to the smear layer when applying a self etch adhesive?

When phosphoric acid is applied to dentin, the smear layer is converted to a liquid form prior to rinsing with water. When using a self-etch primer, the smear layer is dissolved into the primer, and becomes one.

Does EDTA remove smear layer?

The results show that the smear layer can be totally removed by using 10 ml of a four-to-three by volume mixture of EDTA and ethylenediamine for irrigation of instrumented root canals.

Why do we remove the smear layer before obturation?

It is thought that, since the smear layer can contain bacteria, and because it might potentially slough later, it should be removed. Thus, the clinical consensus has been to remove it prior to endodontic obturation.

What happens if you over etch a tooth?

Most hybrid zones are about 10-20 microns in depth, over-etching can lead you to demineralize up to 80 microns in depth, which is too deep for hydrophilic resin to penetrate. This could leave you with a gap of demineralized dentin that will result in a very weak bond.

How do you remove a smear layer?

The solution most frequently used to remove the smear layer is ethylenediaminetetraacetic acid (EDTA) [12].

What is the smear layer made of?

The smear layer is a surface accumulation of debris formed on dentine during instrumentation (Fig. 8.194a). It is composed of organic and inorganic components and forms both a superficial, loosely adherent, layer and a deeper, tightly adherent, layer. There is some debate as to whether the smear layer should be removed or not.

How thick is smear layer in dentistry?

With further instrumentation the material is forced against the canal walls forming a friable and loosely adherent layer. The smear layer is typically 1–2 µm thick, although it can also be found within the dentinal tubules for up to 40 µm. 38

What is smear layer in root canal?

The smear layer, comprising both organic and inorganic components, is found on the root canal walls after endodontic instrumentation.38,39,40 It is composed largely of particulate dentine debris created by endodontic instruments during root canal preparation but also contains pulpal remnants and microorganisms.