Smear layer in endodontics: role and management

The smear layer was first described by McComb and Smith, who demonstrated the presence of an organic layer containing apatite particles on the enamel surface caused by heat generated during cutting [1]. In endodontics, the smear layer term was used to describe the amorphous and irregular particles that resulted from root canal instrumentation and covered all instrumented surfaces of the prepared root canals. The thickness of the smear layer may vary from tooth to tooth according to several factors including: wet or dry cutting of the dentin, size and shape of the root canal, shape and sharpness of instruments, and the type and amount of the irrigating solution [2].