The primary goal of modern dentistry is the preservation of as much natural tooth structure as possible. Nickel titanium (NiTi) instruments are primarily selected to reduce the aggressiveness of hand instruments within the root canal, to maintain normal root canal anatomy, and to standardize root canal instrumentation. NiTi instruments remove a conservative amount of root dentin. When commercially available, preformed drills and/or Largo drills are used a large amount of root canal dentin is removed, enlarging the diameter of the canal. Recently a NiTi instrument (Mtwo, VDW, Munich, Germany) for removing only the gutta-percha during post space preparation has been proposed. This instrument is highly flexible and does not cut laterally, thus preserving the root canal dentin.
The removal of the gutta-percha from the root canal walls must be followed by the use of ultrasonics and EDTA for complete cleansing of the root canal walls of endodontic cement and residual gutta-percha, and to permit surface contact between the luting/adhesive agent and the dentinal walls. The efficacy of this procedure has been recently demonstrated (Coniglio, 2008). The diameter and size of the Mtwo NiTi drills correspond to the smaller-sized fiber posts that are commercially available.
The use of fiber posts is a treatment intended to conserve remaining tooth structure. A frequently used procedure, the fiber-post technique is followed by a choice of various therapeutic options, and many factors have to/>