Effect of quad helix combined with a tongue crib in growing Class III patients with maxillary deficiency: a pilot clinical investigation

Skeletal Class III malocclusion with maxillary deficiency and posterior crossbite requires early interceptive treatment. This pilot clinical investigation evaluated the effects of a fixed quad helix combined with a tongue crib in growing patients with skeletal Class III malocclusion and posterior crossbite over a six-month period. Seven children (mean age 8.28 ± 0.48 years; four boys) at cervical vertebral maturation stage CS1 received a fixed quad helix bonded to the maxillary first molars, combined with four to five palatal tongue cribs (0.9 mm wire, 12–15 mm in height). Lateral cephalometric radiographs were obtained before treatment (T1) and after six months (T2). Skeletal, dental, and soft-tissue parameters were compared using the paired samples t-test and the Wilcoxon signed-rank test (α = 0.05). Posterior crossbite was resolved in all patients. Significant improvements were observed in SNA (+ 4.28°, p = 0.001), ANB (+ 4.20°, p = 0.018), and the Jarabak index (+ 6.00%, p = 0.04). Dentally, overjet (+ 3.28 mm, p = 0.001), overbite (+ 2.07 mm, p = 0.01), and IMPA (− 9.71°, p = 0.004) improved significantly. The convexity and nasolabial angles also changed significantly, whereas SNB, mandibular length, and lip measurements showed no significant change. Within the limitations of this study, treatment with a combined quad helix and tongue crib appliance was associated with significant improvements in sagittal skeletal and dental relationships and in the soft-tissue profile, and resolved the posterior crossbite in all patients in the early mixed dentition. These preliminary findings require confirmation in multicenter randomized controlled trials with longer follow-up.