title: The effect of root preparation technique and instrumentation length on the development of apical root cracks.
abstract: The purpose of this study was to compare the effects of root canal preparation techniques and instrumentation length on the development of apical root cracks. Forty extracted mandibular premolars with straight roots were randomly selected and mounted on resin blocks with simulated periodontal ligaments, and the apex was exposed. The teeth were divided into four groups of 10 teeth each for different canal preparation techniques and instrumentation lengths: group A: step-back preparation (SB) with stainless steel files (SF) using root canal length (RCL) to guide instrumentation length; group B: SB using RCL - 1 mm; group C: crown-down preparation (CD) with Profile using RCL; and group D: CD with PF using RCL - 1 mm. Digital images of the instrumentation sequence were compared for each tooth. Statistical analysis revealed a significant effect of instrumentation length (p < 0.05) but no significant effect of preparation technique (p > 0.05) on the development of apical cracks.
authors.affiliation: Tokyo Medical and Dental University, Pulp Biology and Endodontics, Tokyo, Japan. c.adorno.endo@tmd.ac.jp
authors.forename: Carlos G
authors.initials: CG
authors.lastname: Adorno
authors.forename: Takatomo
authors.initials: T
authors.lastname: Yoshioka
authors.forename: Hideaki
authors.initials: H
authors.lastname: Suda
mesh_terms: D001641:Bicuspid; D003762:Dental Instruments / Q000009:adverse effects; D003799:Dental Stress Analysis; D003804:Dentin / Q000293:injuries; D004867:Equipment Design; D006801:Humans; D018915:Root Canal Preparation / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D019227:Tooth Apex / Q000293:injuries*; D014082:Tooth Fractures / Q000209:etiology*