Current Assessment of Reciprocation in Endodontic Preparation: A Comprehensive Review—Part I: Historic Perspectives and Current Applications

• Up to date, small stainless steel reciprocating files are still used in the initial treatment phases.
• Future studies are needed to evaluate the use of small stainless steel files for reciprocation.
• Current reciprocation movements show considerable variations.
• Contemporary nickel-titanium reciprocating files present an evolution in the preparation techniques.
• The proposed classification for reciprocation movements may enable an easier understanding of current systems.

IntroductionDuring the evolution of mechanical instrumentation in endodontics, an important role has been played by reciprocating stainless steel files using horizontal rotational, vertical translational, or combined movements. These kinds of systems are still in use mainly as an accessory to help in the first phases of the treatment.MethodsThe literature concerning these systems has been analyzed using selected criteria.ResultsThe latest evolution of horizontal rotational reciprocating movement brought to the development of a different kind of movement in which the angles are asymmetrical and that appears to be ideal in conjunction with modern nickel-titanium (NiTi) files with a greater taper. Initially, this movement was limited to particular handpieces available on the market that was used with existing NiTi files to complete root canal instrumentation. Later on, specific files and proprietary motors were introduced into the market. The differences between reciprocating motion used for NiTi and stainless steel files are described and critically analyzed.ConclusionsA classification of the different mechanical reciprocating motions used is presented, thus enabling an easier understanding of these systems and anticipated future developments.