title: Effect of nickel titanium file design on the root surface strain and apical microcracks.
abstract: The aim of this study was to determine the effect of nickel titanium file design on the root surface strain generated and apical microcracks caused during canal shaping. Thirty-three mandibular incisors were distributed into LightSpeed X, FlexMaster and a control group. A strain gauge was fixed apically on the proximal root surface to determine the maximum strain during canal shaping. Except for the control group, all root canals were enlarged to size 50. Images were taken after removing the apical 1 and 2 mm of the root end. Mean maximum strain values and presence of microcracks were statistically compared using the t-test and chi-square test, respectively. During canal shaping, the strain increased cumulatively with mean maximum strains of 808.2 ± 228.8 and 525.1 ± 168.9 microstrain in LightSpeed X and FlexMaster, respectively (P = 0.004). Both systems caused comparable microcracks. Although LightSpeed X produced higher maximum strain, no difference in microcrack development was found between both systems.
authors.affiliation: Endodontics, College of Dentistry, King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, National Guard Health Affairs, Riyadh, Saudi Arabia.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Jamleh
authors.affiliation: Endodontics and Research Methodology, School of Dentistry, National University of Asuncion, Asuncion, Paraguay.
authors.forename: Carlos G
authors.initials: CG
authors.lastname: Adorno
authors.affiliation: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Arata
authors.initials: A
authors.lastname: Ebihara
authors.affiliation: Department of Pulp Biology and Endodontics, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Suda
mesh_terms: D000497:Alloys; D003722:Dental Alloys; D003786:Dental Pulp Cavity; D004867:Equipment Design; D018915:Root Canal Preparation; D014092:Tooth Root
chemical_list: D000497:Alloys; D003722:Dental Alloys; C013616:nitinol
keywords: FlexMaster; LightSpeed X; microcrack; root surface strain