Biomechanical evaluation of an orthodontic mini-implant with plastic removal cap: an in-vitro experimental testing

This study evaluates the biomechanical interactions of a mini-implant using a plastic revolving cap (PRC) with translation/rotation features for optional orthodontic traction. An orthodontic mini-implant and the PRC consisting of a hexagon connection onto mini-implant with 60 degree switching unit and an extended arm to provide orthodontic wire tied at different positions. The PRC removal force was measured by pull-out testing. The PRC removal force remained larger than three times the finger pulling force (9.3N) after 5 repeated removal tests. The results for the PRC resistant testing showed that the PRC rotational resistant force (20.31±0.83N) is larger than the maximum traction force (about 4.9N) for orthodontic treatment. The mini-implant used with PRC can provide translation and rotation features to change the angles and directions of orthodontic tractions for most effective anchorage preparation under safety consideration.