Cone-beam computed tomography evaluation of mini-implants after placement: Is root proximity a major risk factor for failure?

INTRODUCTION: The purposes of this study were to determine factors favoring successful mini-implant placement and to evaluate root proximity as a possible risk factor for failure of osseointegration-based mini-implants during orthodontic treatment.

METHODS: Three-dimensional cone-beam computed tomography images were used to examine 50 sandblasted, large-grit, and acid-etched surface-treated mini-implants (C-implant, Seoul, Korea) placed in 25 patients. The images were analyzed for 3-dimensional position of the mini-implant (placement angle and depth) and any contact with root surfaces or maxillary sinuses.

RESULTS: There were no remarkable differences in horizontal placement angles in the axial plane and placement depths of the mini-implants, but the vertical placement angle was significantly higher on the left side (24.5 degrees +/- 11.0 degrees ) compared with the right side (11.8 degrees +/- 11.6 degrees ). The horizontal mini-implant placement angle had a greater inclination tendency toward the maxillary first molar, and 11 mini-implants with root proximity showed mesiobuccal contact with the maxillary first molar root. Only 1 failure in 15 mini-implants with root proximity and 1 failure in 35 without root proximity were observed on the images.

CONCLUSIONS: Root proximity alone was not considered a major risk factor for osseointegration-based mini-implant failure.