Preparation of the root canal system

The key factor in the development of pulpal inflammation and apical periodontitis is the presence of bacteria [42]. It has been widely accepted that bacteria and/or their products are the main aetiological factors in the initiation and progress of these diseases [10]. Consequently, the central focus of root canal treatment has been directed towards the elimination of bacteria and their substrates from the pulp canal system. This may involve removal of necrotic pulp and tissue debris, removal of an inflamed pulp or, in elective treatment, the removal of healthy tissue. Retreatment of failing cases is addressed in Chapter 13. Historically, a mechanistic approach to root canal treatment was frequently adopted, but in recent years a greater awareness of the complexities of the root canal system (Fig. 6.1) has led to the development of newer techniques, instruments and materials. These new developments have greatly enhanced the clinician’s ability to achieve the biologically-based objectives of root canal treatment, which include: