LAUSR

INTRODUCTION The aim of this study was to evaluate the transportation and centring ability of five different rotary and reciprocating file systems with different metallurgical properties and surface treatments in curved root canals. METHODS Fifty mesiobuccal round canals of upper molars with cuvature of 25-40° were assigned to five experimental groups (n=12) according to the instrumentation system used: ProTaper Next (PTN); Reciproc Blue (RCB); Reciproc (RC); TruNatomy (TRN); XP-endo Shaper (XPS). During instrumentation, 5 mL of 2.5% NaOCl was used in each root canal. The final irrigation protocol included 15% ethylenediaminotetraacetic acid followed by NaOCl irrigation. The micro-CT scanning of the samples was performed before and after instrumentation to analyse the transportation and centring ability at three canal levels. The results were analysed with one-way ANOVA test with corresponding post hoc test. RESULTS Overall, RCB caused significantly more canal transportation compared to the other techniques (p<0.05). There were no significant differences between the other techniques (p>0.05). The PTN had a significantly better ability to stay within the central axis of the root canal compared to the RC and RCB techniques (p=0.046, p=0.017). In the apical third, all techniques caused similar apical transportation and centring ability (p>0.05). In the middle and cervical parts of the canal, the RCB caused a significantly greater canal transportation than other techniques (p<0.05). CONCLUSIONS Under the limitations of this study, all tested techniques had similar transportation and centring abilities in the apical part of the canal. However, overall results and those in the middle and coronal parts of the canal indicated that reciprocating instruments resulted in more canal transportation and less centred preparations.