Modified Crown-Down Filing Technique
Initially, hand files should be used to access the root canal, create a glide path, and determine working length. Hand files should then enlarge the canal at working length to at least a 20/.02 to 30/.02 file size. The size will depend on the actual tooth that is being treated. After this step, rotary-file instrumentation should be initiated. It has been documented in scientific literature that rotary nickel-titanium (NiTi) files can prepare a canal faster than hand files.32
Although there are many different file techniques for conventional endodontic treatment, the modified crown-down technique is a consistent and efficient method of treatment.33 The technique involves opening the coronal two-thirds of the canal with rotary files. Several types of “orifice opener” rotary files are on the market. Next, the rotary files should be taken to working length and worked up from smaller- to larger-size files. It is recommended to use a 0.04 taper rotary-file system when preparing the root canal for obturation. The last rotary-file size that can be taken to working length in a canal is considered the master apical file.
A clinician must use a rubber dam for tooth isolation when performing endodontic treatment. Also, the occlusion should be adjusted before endodontic access on posterior teeth. This will aid in providing consistent file reference points and reducing postoperative periodontal-ligament inflammation.34