title: Analysis of time to failure of orthodontic mini-implants after insertion or loading.
abstract: OBJECTIVE
  This study was performed to evaluate patterns of failure time after insertion, failure rate according to loading time after insertion, and the patterns of failure after loading.
  
  
  METHODS
  A total of 331 mini-implants were classified into the non-failure group (NFG) and failure group (FG), which was divided into failed group before loading (FGB) and failed group after loading (FGA). Orthodontic force was applied to both the NFG and FGA. Failed mini-implants after insertion, ratio of FGA to NFG according to loading time after insertion, and failed mini-implants according to failed time after loading were analyzed.
  
  
  RESULTS
  Percentages of failed mini-implants after insertion were 15.79%, 36.84%, 12.28%, and 10.53% at 4, 8, 12, and 16 weeks, respectively. Mini-implant failure demonstrated a peak from 4 to 5 weeks after insertion. The failure rates according to loading time after insertion were 13.56%, 8.97%, 11.32%, and 5.00% at 4, 8, 12, and 16 weeks, respectively. Percentages of failed mini-implants after loading were 13.79%, 24.14%, 20.69%, and 6.9% at 4, 8, 12, and 16 weeks, respectively.
  
  
  CONCLUSIONS
  Mini-implant stability is typically acquired 12 to 16 weeks after insertion, and immediate loading can cause failure of the mini-implant. Failure after loading was observed during the first 12 weeks.
authors.affiliation: Department of Orthodontics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea.
authors.forename: Jong-Wha
authors.initials: JW
authors.lastname: Jeong
authors.affiliation: Department of Orthodontics, Section of Dentistry, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Jong-Wan
authors.initials: JW
authors.lastname: Kim
authors.affiliation: Department of Orthodontics, Section of Dentistry, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Nam-Ki
authors.initials: NK
authors.lastname: Lee
authors.affiliation: Department of Oral and Maxillofacial Surgery, Section of Dentistry, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Young-Kyun
authors.initials: YK
authors.lastname: Kim
authors.affiliation: Department of Oral and Maxillofacial Surgery and Oral Cancer Center, School of Dentistry and Dental Research Institute, Seoul National University Dental Hospital, Seoul, Korea.
authors.forename: Jong-Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Orthodontics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea.
authors.forename: Tae-Woo
authors.initials: TW
authors.lastname: Kim
keywords: Dental implant; Immediate dental implant loading; Orthodontic anchorage procedure