Evaluation of the success and complication rates of self-drilling orthodontic mini-implants

Orthodontic mini-implants are important devices for successful anchorage management in orthodontics; however, the survival of these devices depends on several clinical factors. The aim of our study was to calculate the success and complication rates of orthodontic mini-implants.

In this retrospective study, patients of our orthodontic department were enrolled, getting overall 59 orthodontic mini-implants during their orthodontic treatment in a 2-year period. Every patient had one or more of the 1.6 mm × 8 mm in size self-drilling mini-implants (Jeil Dual Top Anchor System, Jeil Medical Corp., Seoul, Korea). Screw loading was performed immediately after insertions, keeping tension forces under 150 g. Soft tissue and bone infections, implant mobility and screw loss, implant fracture, and neighboring tooth injury were registered. Relationships between variables were tested using the Chi-square test for statistical significance.

The success rate of the orthodontic mini-implants was 89.8% in this study while the average loading period was 8.1 months. Soft-tissue infections varied between 6.3% and 33.3% of the cases while screw mobility varied between 3.1% and 20.8% of the cases regarding the anatomic localization. Screw mobility was significantly more frequent in the buccal fold than in the palate (P = 0.034). Screw mobility was significantly more frequent in the buccal fold than in the palate (P = 0.034) and screw mobility was found more frequently in case of intrusions than by extrusions (P = 0.036).

The overall success rate of mini-implants was found acceptable in this study, however, screw mobility in the buccal fold showed a high incidence, suggesting the thorough consideration of the immediate loading by buccal mini-implants.