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Micro-computed tomographic assessment of dentinal microcrack formation in straight and curved root canals in
J C L G D Martins1, B P Oliveira1, D A Duarte2
1Department of Prosthodontics and Oral and Maxillofacial Surgery, Dental School, Recife, PE, Brazil.
Aim:
To compare microcrack formation in roots of extracted teeth after the shaping of straight and curved root canals with hand, rotary and reciprocating files using micro-computed tomographic (micro-CT) analysis.
Methodology:
Thirty straight mandibular incisors and 30 severely curved mesial roots of mandibular molars were randomly divided into 6 experimental groups (n = 10) according to the systems used for the root canal preparation and the root canal curvature: ProTaper Universal for Hand Use (Dentsply Sirona, Ballaigues, Switzerland), HyFlex EDM (Coltene-Whaledent, Altstätten, Switzerland) and Reciproc Blue (VDW, Munich, Germany) files used in mandibular incisors (straight canals) and mesial roots of mandibular molars (curved canals). The roots were imaged with micro-CT scanning at an isotropic resolution of 14 μm before and after root canal preparation, and the cross-sectional images generated were assessed to detect microcracks.
Results:
All dentinal defects identified after root canal preparation were already present before instrumentation, and no new microcracks were detected. Dentinal microcracks were present in 19% (ProTaper Universal for Hand Use), 11% (Hyflex EDM) and 23% (Reciproc Blue) of the cross-sections when the instrumentation was performed in mandibular incisors. Instrumentation of mandibular molars revealed microcracks in 15% (ProTaper Universal for Hand Use), 16% (Hyflex EDM) and 17% (Reciproc Blue) of the cross-sections.
Conclusions:
Preparation of straight and curved root canals with ProTaper Universal for Hand Use, HyFlex EDM and Reciproc Blue systems did not produce microcracks in extracted teeth when evaluated with micro-CT.
