title: Effective factors including periodontal ligament on vertical root fractures.
abstract: The purpose of the present study was to analyze effective factors including periodontal ligament on vertical root fractures (VRFs). Eighty maxillary central incisors were assigned to eight groups, depending on master apical file (MAF) size, loading point and existence of a simulated periodontal ligament (PDL). The gutta-percha in the root canal was vertically pressed with a Co-Cr rod using a universal testing machine. An ordinal logistic analysis was employed to determine significant factors. VRFs were observed in 88.8% of the specimens but no horizontal fractures were found. There were three types of VRFs: partial fracture not involving the apex (PF, 41.3%), partial fracture involving the apex (AF, 40.0%), and complete fracture (CF, 7.5%). MAF size significantly affected VRFs (p < 0.05); large MAF size exhibited more partial fractures involving the apex. Loading point and existence of PDL did not affect VRFs.
authors.affiliation: Pulp Biology and Endodontics, Department of Restorative Sciences, Division of Oral Health Sciences Graduate School, Tokyo Medical and Dental University, Tokyo, Japan. okitsu.endo@tmd.ac.jp
authors.forename: Motoko
authors.initials: M
authors.lastname: Okitsu
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Takahashi
authors.forename: Takatomo
authors.initials: T
authors.lastname: Yoshioka
authors.forename: Naohiko
authors.initials: N
authors.lastname: Iwasaki
authors.forename: Hideaki
authors.initials: H
authors.lastname: Suda
mesh_terms: D003762:Dental Instruments / Q000009:adverse effects*; D003799:Dental Stress Analysis; D006801:Humans; D007180:Incisor; D010513:Periodontal Ligament / Q000502:physiology*; D018915:Root Canal Preparation / Q000009:adverse effects / Q000295:instrumentation*; D019227:Tooth Apex / Q000293:injuries; D014082:Tooth Fractures / Q000209:etiology*; D014092:Tooth Root / Q000293:injuries