Biomechanical considerations for controlling target tooth movement with mini-implants

The clinical application of mini-implants enables the clinician to adjust the line of force in various directions as well as the height of the maxillary and mandibular dentition. When vertical control is required during anterior teeth retraction, vertical force can be applied effectively to the center of resistance of the maxillary dentition by placing a mini-implant in a high position. This prevents the anterior teeth from extruding as might occur during anterior teeth retraction. A classic way to correct deep bite is to apply a reverse curve of Spee to the wire for relative intrusion of the mandibular incisors or by using a segmental intrusion archwire. These methods may result in excessive labial tipping of the mandibular incisor, resulting in gingival recession and lip protrusion. To prevent undesired tooth movement, it is suggested to directly intrude the incisors by placing mini-implants in the alveolar bone area between the incisor roots.