RESUMO
OBJECTIVES: To compare two reciprocating NiTi systems operated by novices for use in curved root canals. METHODS: Fifty mesial roots of extracted mandibular first molars, with 2-2 canal configuration, were scanned with micro-CT and divided into 2 groups according to canal length and curvature: Reciproc and WaveOne. Each system was used to prepare one of the two canals by fourth-year dental students, who were new to reciprocating files and were blinded to the system being used. After another scanning, the pre- and post-instrumentation images were compared 3-dimensionally in software. RESULTS: Some 43 to 46% of the canal wall area remained un-instrumented. Significantly higher proportions of canals were transported towards the isthmus or furcation aspect than the mesial or external aspect. Mean transported distance was the greatest in the coronal one-third. Remaining dentine wall was the thinnest at the furcal aspect near the middle root region. No significant difference was noted between the two brands in the parameters examined. CONCLUSIONS: Both brands of reciprocating file left similar amounts of un-instrumented canal wall, and resulted in similar extent of canal transportation. CLINICAL RELEVANCE: NiTi reciprocating files can safely be used by new users to prepare curved root canals into a predictable shape.