Objectives: The purpose of this study was to determine in vitro using a synchrotron radiation-based μCT (SRCT) whether rotary and reciprocating nickel titanium (NiTi) instrumentations lead to the formation of dentine microcracks.
Material and methods: Fourteen extracted human molars were obtained with ethical approval. Seven distobuccal roots of the maxillary molars and seven mesial roots of the mandibular molars were assigned to two experimental groups: (A) prepared with rotary Pro Taper instrumentation (n = 6) and (B) reciprocating WaveOne (n = 6). Irrigation with 1 % NaOCl and 17 % EDTA solutions was carried out. The remaining roots served as positive control with induced fractures (group C). SRCT was used to scan all samples pre and post-operatively. An imaging software was used to determine the number and length of microcracks. Statistical analyses weighed differences between pre and post-instrumentation and between shaping methods.
Results: A significant increase in the number and length of microcracks was detected post-shaping. No significant difference between rotary and reciprocating instrumentation was observed.
Conclusions: Within the limitations of this in vitro study, an increased number and length of microcracks was induced by mechanical instrumentation. Reciprocating and rotary instrumentation are similar in terms of effect.
Clinical significance: Dentinal damage may occur following rotary and reciprocating instrumentation.