Retreatment of an adult patient with skeletal Class II malocclusion, large overjet, and shallow overbite using orthodontic mini-implants and clear aligners

This case report aimed to introduce the retreatment concept of adult patients with skeletal Class II malocclusion and large overjet using orthodontic mini-implants (OMI) and clear aligners. A 26-year-old woman had a history of fixed treatment with the extraction of her four first premolars and splint therapy because of temporomandibular disorder. She had a normally positioned maxilla (SNA, 82.1°), retrusive mandible (SNB, 74.0°), skeletal Class II malocclusion (ANB, 8.1°; overjet, 6.9 mm), and shallow overbite (0.4 mm). In stage 1 treatment, with the help of four OMIs installed at the palate and the buccal attached gingiva of the mandible, a series of 34 clear aligners were applied to obtain intrusion of the maxillary and mandibular posterior teeth and sequential distalization of the maxillary teeth, and mesialization of the mandibular teeth. Counterclockwise rotation of the mandible, distal movement of the maxillary dentition, and mesial movement of the mandibular dentition helped to obtain a Class I relationship. Stage 2 treatment was performed with 15 sets of aligners and OMIs for additional distalization of the maxillary teeth and intrusion of the maxillary and mandibular anterior teeth. Improvement of the retrusive mandible (SNB, 76.0°), Class I relationship, and normal overbite and overjet (3.1 mm; 2.7 mm) were obtained. The total treatment duration was 1 year and 5 months. Treatment outcomes were well maintained at 1-year retention. Combining clear aligners and OMIs might help clinicians obtain good treatment outcomes in retreatment of Class II malocclusion and excessive overjet. However, meticulous monitoring of the counterclockwise rotation of the mandible and the resulting change in overbite and overjet is necessary.