Controlling incisor torque with completely customized lingual appliances

Purpose To test the null hypothesis of no significant deviation between the center of rotation (C ROT ) and the center of resistance (C RES ) during space closure in Angle class II division 2 subjects achieved using a completely customized lingual appliance (CCLA) in combination with class II elastics and elastic chains. Methods This retrospective study included 29 patients (male/female 11/18; mean age 15.6 [13–27] years) with inclusion criteria of an Angle class II/2 occlusion of least of half of a cusp, maxillary dental arch spacing, completed CCLA treatment (WIN, DW Lingual Systems, Bad Essen, Germany) in one center with a standardized archwire sequence and use of class II elastics and elastic chains only. Maxillary incisor root inclination was assessed by X‑ray superimpositions of the maxilla at the beginning (T1) and the end (T3) of CCLA treatment. Using Keynote software (Apple®, Cupertino, CA, USA), the incisor’s C ROT was assessed with the point of intersection of the incisor axes (T1; T3) following vertical correction of overbite changes. C RES was defined at 36% of the incisor’s apex–incisal edge distance. Results The null hypothesis was rejected: the mean C ROT − C RES difference was 52.6% ( p