Endodontic complications of root canal therapy performed by dental students with stainless-steel K-files and nickel-titanium hand files

Straightening of curved canals is one of the most common procedural errors in endodontic instrumentation. This problem is commonly encountered when de ntal students perform molar endodontics. The purpose of this study was to c ompare the effect of the type of instrument used by these students on the e xtent of straightening and on the incidence of other endodontic procedural errors, Nickel-titanium 0.02 taper hand files were compared with traditiona l stainless-steel 0.02 taper K-files. Sixty molar teeth comprised of maxill ary and mandibular first and second molars were treated by senior dental st udents. Instrumentation was with either nickel-titanium hand files or stain less-steel K-files, Preoperative and postoperative radiographs of each toot h were taken using an XCP precision instrument with a customized bite block to ensure accurate reproduction of radiographic angulation. The radiograph s were scanned and the images stored as TIFF files. By superimposing tracin gs from the preoperative over the postoperative radiographs, the degree of deviation of the apical third of the root canal filling from the original c anal was measured. The presence of other errors, such as strip pelf oration and instrument breakage, was established by examining the radiographs. In curved canals instrumented by stainless-steel K-files, the average deviatio n of the apical third of the canals was 14.44 degrees (+/-10.33 degrees). T he deviation was significantly reduced when nickel-titanium hand files were used to an average of 4.39 degrees (+/-4.53 degrees), The incidence of oth er procedural errors was also significantly reduced by the use of nickel-ti tanium hand files.