Smear Layer in Endodontics

One of the main purposes of Endodontic therapy is to disinfect the root canal system, which is accomplished by removing the pulp tissue or necrotic pulp remnants, any microorganisms present in the root canal system and infected dentin. Root canal cleaning and shaping procedures mainly rely on mechanical instrumentation. However, mechanical instrumentation leaves a smear layer covering the dentinal walls. This smear layer is composed of dentin debris, organic material and microorganisms. Smear layer prevents penetration of intracanal medicaments into the dentinal tubules, prevents complete adaptation of obturation materials to the prepared root canal surfaces, and may act as a reservoir for viable microorganisms that may remain in the dentinal tubules.A number of means have been tested for smear layer removal which includes Chemical, Mechanical, Ultrasonic, and Lasers. This book describes various methods of smear layer removal and also describes a scanning electron micoscopic study comparing the smear layer removal efficacies of four different irrigants viz. EDTA, Smear Clear (EDTA + a cationic & anionic surfactant), MTAD, and NaOCl with distilled water as a negative control.