title: [Influence of periodontal ligament injury on initial stability for immediately loaded mini-implant].
abstract: OBJECTIVE
  To evaluate the influence of periodontal ligament (PDL) injury on initial stability for immediately loaded mini-implant anchorage.
  
  
  METHODS
  The sample consisted of 153 adult patients with maxillary protrusion deformity. Guiding by the positioning device designed by Choi, 306 mini-implants were inserted by self-tapping in the upper right and left buccal areas between the first molars and second premolars. The mini-implants were divided into two groups according to CT scanning. The mini-implant was absolutely separated from PDL (group I), the mini-implant appeared to touch or overlay on PDL, but not contact to the adjacent roots (group II). If orthodontic force could be applied to the mini-implants for four months, the mini-implant was recorded as successful anchorage. After immediate loading for four months, the analyses were completed by SPSS 9.0 software.
  
  
  RESULTS
  Of the 306 inserted mini-implants, 162 were absolutely separated from PDL, 136 appeared to touch or overlay on PDL, but not contact to the adjacent roots, and 8 were excluded from this study because of injury to the adjacent root. The success rates of group I and II were 87.0% and 65.4% respectively. There were significant differences in the success rates between the two groups (P<0.001). The differences between the two groups in distribution of the upper right and left area had statistical significance (P<0.05).
  
  
  CONCLUSIONS
  PDL injury is one of the main reasons leading to early loosening of the mini-implant.
authors.affiliation: Dept. of Orthodontics, Stomatological College of Shandong University, Jinan 250012, China.
authors.forename: Hong-Ning
authors.initials: HN
authors.lastname: Wang
authors.forename: Dong-Xu
authors.initials: DX
authors.lastname: Liu
authors.forename: Chun-Ling
authors.initials: CL
authors.lastname: Wang
authors.forename: Tao
authors.initials: T
authors.lastname: Lü
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Hong-Ling
authors.initials: HL
authors.lastname: Wang
mesh_terms: D000328:Adult; D001641:Bicuspid; D015921:Dental Implants; D006801:Humans; D008437:Maxilla; D008963:Molar; D052280:Orthodontic Anchorage Procedures; D016382:Orthodontic Appliance Design; D010513:Periodontal Ligament; D014092:Tooth Root
chemical_list: D015921:Dental Implants