Application of orthodontic mini-implants in adolescents

The aim of this study was to determine the success rate of mini-implants in adolescents, and also whether a latent period is necessary and the optimum placement torque in an attempt to improve the success rate in adolescent patients. There were 57 orthodontic patients involved in the study, with ages ranging from 11.7 to 36.1 years, who underwent surgery to insert mini-implants (169 implants). When a mini-implant endured an orthodontic force applied for 6 months or more without any mobility, it was considered a success. The success rate was 63.8% in the early-load group (less than 1-month latent period) of adolescents, 97.2% in the late-load group (3-month latent period) of adolescents and 91.9% in the adult group. The success rate of the early-load group of adolescents was significantly inferior to those of the other groups (P < 0.01). In measurements of the placement torque in adolescents, the success rate of the 5–10 N cm group was significantly higher than the other groups only in the maxilla of the early-load group. Although the optimum torque could not be defined, a latent period of 3 months before loading is recommended to improve the success rate of the mini-implant when placed in the alveolar bone in adolescent patients.