title: Removal of an instrument fractured by ultrasound and the instrument removal system under visual magnification.
abstract: The case of a lower molar with apical periodontitis, which had previous root canal treatment and a fractured instrument in the distal root beyond the foramen, is presented.
  
  
  
  The simultaneous presence of a foreign body (endodontic instrument or material) in periapical tissues and microorganisms in the root canal, are etiological factors in the formation or maintenance of a periapical lesion, and can lead to failure in endodontic treatment.
  
  
  
  This instrument was removed through the staging platform technique, by using ultrasound and an Instrument removal system (IRS) microtube under microscope visual amplification. All the canals were re-instrumented, irrigated with sodium hypochlorite and passive ultrasonic irrigation, removal of smear layer and intracanal medication with calcium hydroxide for 8 days, after which they were filled. The symptoms disappeared and clinical and radiograph 2-year follow-up shows healing of periapical tissues.
  
  
  
  The combined use of visual magnification microscope, ultrasound and the IRS system by staging platform technique, allowed the removal of an endodontic instrument beyond the foramen, which made it possible to apply a conventional disinfection protocol.
  
  
  
  Endodontic re-treatment by conservative approach of complicated cases it is an option with good clinical prognosis, before apical surgery or extraction.
authors.affiliation: Professor, Endodontic Postgraduate Program, Research Institute in Biomedical Sciences, CUCS, University of Guadalajara, Av. Francisco Javier Gamboa 230 Col. Arcos Sur, Guadalajara, Jalisco, México, Zip code: 44150, Phone: +52-33 36159804, e-mail: endoacruz@yahoo.com.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Cruz
authors.affiliation: Endodontic Postgraduate Program, CUCS, University of Guadalajara, México.
authors.forename: Claudia Gabriela
authors.initials: CG
authors.lastname: Mercado-Soto
authors.affiliation: Department of Physics, CUCEI, University of Guadalajara, México.
authors.forename: Israel
authors.initials: I
authors.lastname: Ceja
authors.affiliation: Endodontic Postgraduate Program, CUCS, University of Guadalajara, México.
authors.forename: L Gerardo
authors.initials: LG
authors.lastname: Gascón
authors.affiliation: Endodontics Postgraduate Program, CUALTOS, University of Guadalajara, México.
authors.forename: Patricia
authors.initials: P
authors.lastname: Cholico
authors.affiliation: Endodontic Postgraduate Program, Research Institute in Biomedical Sciences, CUCS, University of Guadalajara, México.
authors.forename: Claudia A
authors.initials: CA
authors.lastname: Palafox-Sánchez
mesh_terms: D000328:Adult; D002126:Calcium Hydroxide / Q000627:therapeutic use; D004868:Equipment Failure; D005260:Female; D005500:Follow-Up Studies; D005547:Foreign Bodies / Q000628:therapy*; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D008866:Microsurgery / Q000379:methods; D010482:Periapical Abscess / Q000628:therapy; D010485:Periapical Periodontitis / Q000628:therapy; D010486:Periapical Tissue / Q000473:pathology*; D019233:Retreatment; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000009:adverse effects / Q000295:instrumentation*; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D019553:Tooth, Nonvital / Q000628:therapy; D014464:Ultrasonic Therapy / Q000295:instrumentation / Q000379:methods
chemical_list: D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D006171:Gutta-Percha; D012973:Sodium Hypochlorite; D002126:Calcium Hydroxide
keywords: Fractured instruments; Instrument removal system; ultrasound; Endodontic retreatment; Apical periodontitis.