Preparation of root canal systems includes both enlargement and shaping of the complex endodontic space together with its disinfection. A variety of instruments and techniques have been developed and described for this critical stage of root canal treatment. Although many reports on root canal preparation can be found in the literature, definitive scientific evidence on the quality and clinical appropriateness of different instruments and techniques remains elusive. To a large extent this is because of methodological problems, making comparisons among different investigations difficult if not impossible. The first section of this paper discusses the main problems with the methodology of research relating to root canal preparation while the remaining section critically reviews current endodontic instruments and shaping techniques.

Mechanical preparation of root canals: shaping goals, techniques and means

It has been recognized for many years that root canal instrumentation produces a smear layer that covers the surfaces of prepared canal walls. This layer contains inorganic and organic substances such as fragments of odontoblastic processes and necrotic debris. There is a lack of agreement regarding the effect of the smear layer on the quality of instrumentation and obturation, but the smear layer itself may be infected and may protect the bacteria within the dentinal tubules. Various methods have been used to remove the smear layer. Conflicting results have been obtained from numerous in vitro studies regarding the significance of the presence or the removal of the smear layer.

Clinical implications of the smear layer in endodontics: a review.

A scanning electron microscopic comparison of a high volume final flush with several irrigating solutions: Part 3

http://www.endoexperience.com/filecabinet/Clinical%20Endodontics/Anatomical%20Considerations/MB2%20anatomy/Root%20Morphology.pdf

Root and Root Canal Morphology of the Human Permanent Maxillary First Molar: A Literature Review

https://www.endoexperience.com/documents/corrthesis.pdf

Stephen R. Davis

Papers

The morphology of the prepared root canal: a study utilizing injectable silicone.

Gutta-percha root canal fillings. An in vitro analysis. I.