Clinical indices for orthodontic mini-implants

Orthodontic mini-implants were recently developed and have been widely used in clinics. However, loosening of mini-implants, as well as infection and swelling of mucosal tissue at the placement site, are often observed during orthodontic treatment. Thus, clinical indices are greatly needed for the safe use of orthodontic mini-implants. This article presents information on mini-implants and offers suggestions on indications, placement technique, optimum design, and evaluation of the placement site for mini-implants. The author concludes that 1) mini-implants should be left in the placement site for 3 months before loading to allow for a healing period, which increases the success rate in adolescent patients, 2) placement torque should be considered when tightening mini-implants into bone, as excessively high or low torque results in low stability, 3) mini-implants with optimal screws should be placed in the correct position, and 4) a prepared site should be established in an area with a cortical bone thickness of greater than 1.0 mm, to improve the success rate. Finally, the vector of orthodontic forces in the arrangement with the center of resistance of the entire dental arch should be considered when developing treatment goals.