[Influence of periodontal ligament injury on initial stability for immediately loaded mini-implant].
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.
Wang
Hong-Ning
HN
Dept. of Orthodontics, Stomatological College of Shandong University, Jinan 250012, China.
Liu
Dong-Xu
DX
Wang
Chun-Ling
CL
Lü
Tao
T
Liu
Hong
H
Wang
Hong-Ling
HL
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
D015921:Dental Implants