title: Case report of recurrent temporomandibular joint open lock associated with abrupt reduction of displaced articular disk.
abstract: METHODS
  This report describes the case of a 51-year-old male patient who initially presented at age 23 with a habitual intermittent open lock (at >35mm) in the left temporomandibular joint (TMJ). The patient was able to manage this affliction through rapid-repetition jaw opening and closing. Tomography of the joint showed no irregular morphology, but intraoral examination revealed an occlusal interference at the mandibular left third molar during leftwards excursion. For this patient, alteration of lateral guidance using a palatal plate attached to the maxillary left canine precluded this intermittent open lock, but at 22 years of age, the open lock recurred and could not be relieved by the patient, who was unable to assume an occlusal position. Because conservative treatment was ineffective, a pumping manipulation technique was applied to reduce the open lock, after which the patient has maintained good jaw function. MRI taken before and after repositioning indicated that abrupt reduction of a displaced articular disk was the cause of the open lock, and that this articular disk was restored to its proper position during the manipulation.
  
  
  CONCLUSIONS
  Most TMJ open locks occur as anterior dislocation, where the mandibular head becomes trapped anterior to the articular eminences, causing excessive opening and difficulty closing. Our clinical findings from this patient indicate that open lock can occur through abrupt reduction of a displaced articular disk, particularly in patients with chronic internal derangement of the TMJ.
  
  
  CONCLUSIONS
  TMJ open lock can occur following abrupt reduction of a displaced articular disk.
authors.affiliation: General Dentistry, Tokushima University Hospital, Tokushima, Japan. Electronic address: keisuke@tokushima-u.ac.jp.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nishigawa
authors.affiliation: Functional Oral Care and Welfare, The University of Tokushima, Tokushima, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Nakano
authors.affiliation: Center for Advanced Dental Health Care, Tokushima University Hospital, Tokushima, Japan.
authors.forename: Teruaki
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: The University of Tokushima, Tokushima, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Bando
authors.affiliation: Department of Stomatognathic Function and Occlusal Reconstruction, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan.
authors.forename: Yoshizo
authors.initials: Y
authors.lastname: Matsuka
mesh_terms: D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage; D003766:Dental Occlusion; D006801:Humans; D007270:Injections, Intra-Articular; D004204:Joint Dislocations / Q000150:complications*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D026201:Musculoskeletal Manipulations / Q000379:methods; D019152:Paracentesis / Q000379:methods; D012008:Recurrence; D013582:Synovial Fluid; D019224:Temporomandibular Joint Disc / Q000473:pathology; D013705:Temporomandibular Joint Disorders / Q000175:diagnosis* / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D016896:Treatment Outcome; D014313:Trismus / Q000175:diagnosis* / Q000209:etiology* / Q000473:pathology / Q000628:therapy; D055815:Young Adult
chemical_list: D000779:Anesthetics, Local
keywords: Articular disk displacement; MRI; Mandibular movement; Open lock; Temporomandibular joint