Evaluation of success rate of endodontic treatment performed by students with stainless-steel K-files and nickel-titanium hand files

A previous study by our group found nickel-titanium (NiTi) 0.02 hand files maintained the original canal shape better than similar stainless-steel K-files (SS-K), Inexperienced dental students used both file types on molar teeth. The purpose of this study was to compare the l-yr success rate of endodontic treatment of the same teeth used in our previous study. Twelve-month follow-up radiographs were compared with the immediate follow-up radiographs, Both sets of radiographs were taken with the same customized stent. Quantification of osseous changes using digital imaging was used. Thus, a reliable numerical estimation (densitometric ratio) of disease and healing processes could be established. Sixty-seven percent of the patients returned for the 12-month radiographs (19 NiTi vs. 21 SS-K), Immediate postoperative periapical status was found to be similar (p > 0.05), Teeth instrumented with the NiTi files demonstrated a higher mean change in densitometric ratio, compared with SS-K files (p < 0.05), Further tests of success (values: <greater than or equal to>0) and failure (value: less than or equal to0) with the Fisher exact test showed more success (down arrow radiographic density) with NiTi files and more failures (up arrow radiographic density) with SS-K type files (p less than or equal to 0.03), This study indicates that maintaining the original canal shape after instrumentation leads to a better prognosis of endodontic treatment.