Successes and failures with orthodontic mini-screws: a retrospective clinical study of 95 mini-screw implantations

The use of mini-screws has increased broadly over the last ten years. Effectively, these implantable devices, greatly reduced in size and easy to set in place and to remove, have provided orthodontists with a low cost means of reinforcing anchorage for a pre-determined period of time. However, their success rate is far from satisfactory compared to the well-established implants used for tooth replacement or for other sources of skeletal anchorage. In a recent meta-analysis Schätzle reported a failure rate of 16.4% for mini-screws as opposed to 10.5% for palatal implants and only 7.3% for mini-plates. The Faculty of Dental Surgery, Paris 7, determined, accordingly, that there was need for a retrospective study on the use of mini-screws. Beyond a simple calculation of the failure rate, we felt it was especially important for us to try to gain an understanding of the most dangerous risks so that they could be avoided in the future.