Treatment outcomes of class II malocclusion with total arch distalization using infrazygomatic crest screws: a retrospective study

BACKGROUND: This study aimed to assess the skeletal, dental, and soft-tissue changes after total maxillary arch distalization using infrazygomatic crest (IZC) miniscrews followed by fixed orthodontic treatment in patients with moderate Class II malocclusion. MATERIALS AND METHODS: 31 patients (including 11 males and 20 females, mean age of 15.48 ± 2.81 years) were treated with fixed orthodontic treatment combined with IZC miniscrew-assisted distalization. After the leveling of the maxillary dental arch, IZC screws (diameter: 2 mm; length: 12 mm) were inserted between the maxillary first and second molars, applying 300 g of force with elastomeric chains. Pre-treatment (T1) and post-treatment (T2) lateral cephalometric radiographs were obtained. RESULTS: The average treatment duration was 2.40 ± 0.86 years. In skeletal measurements, no significant change was detected in the mandibular plane angle. In dentoalveolar measurements, the maxillary first molars were distalized by 2.59 mm, intruded by 0.52 mm, and showed 1.71° of distal tipping. Maxillary incisors were retruded (-1.16 mm), while mandibular incisors demonstrated protrusion (L1-NB: +0.66 mm). A significant increase of 1.67° was observed in the SN/OP angle. Overjet and overbite were reduced by 2.33 mm and 1.28 mm, respectively. Upper lip retrusion (-0.88 mm) indicated favorable soft tissue changes. CONCLUSIONS: Total maxillary arch distalization using IZC miniscrews followed by fixed orthodontic treatment may be an effective non-extraction approach for Class II correction. Controlled maxillary molar distalization with minimal distal tipping was achieved; however, the limited amount of molar intrusion suggests that vertical-control effects should be interpreted cautiously.