title: [A retrospective study of six fractured platform-switching abutments].
abstract: OBJECTIVE
  To explore the reasons for platform-switching abutment fracture, the treatment and prevention methods.
  
  
  METHODS
  Between March 2009 and December 2014, all of the fractured platform-switching abutments were evaluated. The fracture rate of platform-switching abutments was calculated and the gender, age, implant site, implant size, abutment size, prosthetic type, loading time and crown materials were analyzed.
  
  
  RESULTS
  A total of 2 487 platform-switching implants were placed during this period and 6 abutments were fractured. The fracture rate was 0.24% (6/2 487). All of the 6 fractured abutments were placed in molar region. All occlusal planes were made of metal material. Five patients were male. All the fracture abutments could not be removed and the implants had to be removed and reimplanted.
  
  
  CONCLUSIONS
  Without special abutment removing instruments, it is difficult to remove the fractured platform-switching abutment. In molar region, platform-switching implant system should be carefully used. Increasing implants number and splinting crowns with porcelain occlusal planes might reduce the abutment fracture risk.
authors.affiliation: The Fouth Outpatient Dental Clinic, Peking University School and Hospital of Stomatology, Beijing 100025, China.
authors.forename: Yibo
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Email: qiulixin@263.com.
authors.forename: Lixin
authors.initials: L
authors.lastname: Qiu
authors.forename: Jianhui
authors.initials: J
authors.lastname: Li
authors.forename: Ye
authors.initials: Y
authors.lastname: Lin
mesh_terms: D003442:Crowns; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D008297:Male; D008963:Molar; D012189:Retrospective Studies
chemical_list: D003776:Dental Porcelain