title: Success rate and risk factors associated with mini-implants reinstalled in the maxilla.
abstract: OBJECTIVE
  To determine the difference in the success rate for two types of oral installed mini-implants (OMIs): one type of initially installed OMI and a new implant of the same type that is reinstalled.
  
  
  METHODS
  The subjects consisted of 58 patients (19 male, 39 female; mean age = 21.78 +/- 5.85 years) who had received at least one OMI (self-drilling type, conical shape with 2.0-mm upper diameter and 5-mm length) in the attached gingiva of the upper buccal posterior regions for maximum anchorage during en masse retraction. If an OMI failed, a new one was immediately installed in the same area after 4 to 6 weeks or in an adjacent area immediately. The total number of initially installed OMIs (II-OMI) was 109 and the total number of reinstalled OMIs (RI-OMI) was 34. Statistical analysis was performed using chi2 test, Kaplan-Meier method, log-rank test, and Cox proportional hazards regression model.
  
  
  RESULTS
  The success rate and mean duration were 75.2% and 10.0 months, respectively, for II-OMI and 66.7% and 6.4 months, respectively, for RI-OMI. Age, vertical skeletal pattern, and site and side of implantation were not related to the success rates of II-OMI and RI-OMI. Log-rank test showed that II-OMI in males and Class III malocclusions were more prone to failure. The relative risk of II-OMI failure in Class III malocclusions as opposed to Class I malocclusions was 5.36 (95% confidence interval, 2.008 to 14.31, P = .001).
  
  
  CONCLUSIONS
  The success rate of the II-OMI was not statistically different from that of the RI-OMI. Sex and ANB angle might be more important factors for better II-OMI results.
authors.affiliation: Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, South Korea.
authors.forename: Seung-Hak
authors.initials: SH
authors.lastname: Baek
authors.forename: Bo-Mi
authors.initials: BM
authors.lastname: Kim
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Kyung
authors.forename: Joong Ki
authors.initials: JK
authors.lastname: Lim
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001641:Bicuspid; D002648:Child; D003724:Dental Arch / Q000601:surgery; D015921:Dental Implants; D017267:Dental Prosthesis Design; D004868:Equipment Failure; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla / Q000601:surgery*; D008963:Molar; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D009969:Orthodontic Wires; D016016:Proportional Hazards Models; D012086:Reoperation; D012307:Risk Factors; D012737:Sex Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants