Torque control of maxillary anterior teeth with the double J retractor and palatal miniscrews during en masse retraction:

Abstract

A double J retractor (DJR) and palatal miniscrews were used to retract maxillary anterior teeth after failure of the buccal posterior miniscrews. The line of action passing through the center of resistance of the maxillary anterior teeth and the moment generated by the palatal miniscrews via torquing springs successfully controlled the overbite and incisor torque during space closure. The DJR and palatal miniscrews work well with labial fixed appliances to address bimaxillary protrusion.

Clinical Application and Biomechanics of Various Lingual Retractors with Temporary Skeletal Anchorage Devices: A Narrative Review

“…To our knowledge, no study has analyzed the treatment results for improving anterior protrusion using DJR; therefore, all case reports related to DJR have been reviewed, including three Class II cases [14,30,34]. Liaw et al reported two extraction cases in skeletal Class II patients with anterior protrusion using DJR [23,31]. In the first case, a DJR designed to allow a helical torquing spring to be activated directly on the mini-implant was fabricated by placing two miniscrews on the palatal slope [31].…”

“…The torquing spring was placed approximately 8 mm from the gingival line along the palatal mini-implant between the second premolar and first molar. Additionally, Liaw et al reported a case using this design [23,31]. Park et al [14] and Joo [22] reported designs made with elastics (Figure 5).…”

“…Figure 9a shows that the direction of the force passing above and below the CR of the anterior teeth is equal to the direction of force passing through the CR. Class II intermaxillary elastics generates the forward rotation moment of the anterior teeth [23,31]. Figure 9b shows the direction of force that passes through the CR of the anterior teeth, allowing bodily movement of the anterior teeth.…”

“…During retraction, a downward force can be generated by contacting the mini-implants with a torquing spring. Therefore, it creates the forward rotation moment in the anterior teeth [23,31].…”

“…During retraction, a downward force can be generated by contacting the mini-implants with a torquing spring. Therefore, it creates the forward rotation moment in the anterior teeth [23,31]. Figure 9a shows that the direction of the force passing above and below the CR of the anterior teeth is equal to the direction of force passing through the CR.…”