Circumferential Filing Technique in Root Canals

Introduction to Root Canal Treatment

• Successful root canal treatment is based on establishing an accurate diagnosis, developing an appropriate treatment plan, and performing debridement, disinfection, and obturation of the entire root canal system.

Cleaning and Shaping of Root Canal System

• The term "Cleaning and Shaping" or "Shaping and Cleaning" was introduced by SCHILDER H in 1974.
• Cleaning and shaping refer to the removal of all organic substrate from the root canal system and the development of a form within each canal for receiving a dense and permanent root canal filling.
• Shaping and cleaning are often used to describe root canal treatment procedures, reversing the order to reflect the fact that enlarged canals direct and facilitate the cleaning action of irrigants and the removal of infected dentin.

Objectives of Cleaning and Shaping

• To remove all organic substrate from the root canal system.
• To develop a form within each canal for receiving a dense and permanent root canal filling.

Apical Preparation

• Apical matrix or barrier is created at the proper working length to serve as a stop for gutta percha and to prevent materials from extruding into the periapical tissues.
• Apical foramen configuration, canal shape, and size influence the choice of obturation technique.
• Apical constriction is defined as the narrowest portion of the canal, with an average distance from the foramen to the constriction of 0.5 mm.

Techniques for Cleaning and Shaping

Circumferential Filing

• Defined as moving the file around the circumference of the canal space.
• Technique: insert the file into the canal until desired length, engage it to the dentin wall by applying lateral pressure, and withdraw the file.
• Used in large canals with open apex, and choice of instrument is H-File.

Reaming

• The term "ream" indicates clockwise or right-hand rotation of an instrument.
• The cutting edges of reamers are spiral around the shaft of the instrument and cause them to slide into the canal as the edges rotate to the right.
• The motion of reaming is a simple clockwise or right-hand rotation of the instrument.

Refining Phase

• Refining of the root canal by Master apical file no 25 by circumferentially filing the canal walls to achieve smooth taper.

Step-Back Technique

• Advantage: less likely to cause periapical trauma, facilitates removal of more debris, and creates a small apical preparation.
• Disadvantages: significant apical extrusion of debris, apical blockage, canal deviation, time-consuming, and alteration of working length.

Crown-Down Technique

• Steps: coronal preparation, mid-root, apical final preparation.
• Advantages: removal of coronal interference, straighter access to the apical third, removal of canal contents and micro-organisms, increased space for instrumentation and irrigation, minimal apical extrusion of debris, enhanced working length, easy to remove pulp stones, and increased access allows greater control.
• Disadvantages: more time-consuming than step-back technique, excessive flaring at the coronal and middle third may weaken the roots, and use of end cutting instruments in small and calcified canals may cause perforation.

Comparison of Techniques

• Step back vs Crown down: both techniques have their advantages and disadvantages, and the choice of technique depends on the specific case.