Interceptive aligner treatment in a growing Class II, Division 1 patient

Initial diagnosis and records

A 10-year-old male patient presented in the late mixed dentition with the chief complaint of severe crowding, protrusive maxillary incisors and traumatic overbite. The patient requested alignment of all teeth and reduction of the maxillary incisor prominence.

Clinical and radiographic evaluation revealed (Figs. 1–3):

• a bilateral full-cusp Class II molar relationship;
• an increased overjet of 11.7 mm;
• a traumatic overbite of 7.2 mm; and
• a narrow, collapsed V-shaped maxillary arch with a 2.0 mm midline deviation to the right.

Cephalometric analysis confirmed a Class II skeletal pattern primarily caused by mandibular retrusion (ANB = 5°; SNB = 69°) and showed reduced mandibular length (94 mm versus a norm of approximately 110 mm; Fig. 4; Table 1). The vertical pattern was normo-divergent (SN/GoGn = 34°). Dentoalveolar analysis showed severe maxillary incisor proclination, pronounced crowding in both arches and an accentuated curve of Spee. Soft tissue analysis showed lower lip entrapment associated with the increased overjet, contributing to an unfavourable facial profile.

First phase of treatment

The initial aligner series consisted of 20 stages per arch, and the aligners were changed every ten days and worn for 22 hours per day. During treatment, eruption of the permanent premolars and canines led to reduced aligner fit, requiring refinement with an additional series of aligners.

The first phase of treatment was completed after approximately 18 months. At completion, all the permanent teeth had erupted, allowing immediate transition into the second phase of treatment on the same day.

At the end of the first phase of treatment, the clinical findings included (Figs. 5 & 6):

• Class I molar and canine relationships on the left side;
• half-cusp Class II relationships on the right side;
• normal overjet (2.0 mm) and overbite (2.5 mm); and
• a posterior open bite, particularly on the left side.
• Cephalometric analysis showed that the sagittal discrepancy had been significantly reduced (ANB = 3.7°; Wits = 1.8 mm). Mandibular length remained below normative values.

The second phase of treatment and results

The treatment objectives of the second phase of treatment focused on:

• correction of the posterior open bite;
• finalisation of a bilateral Class I relationship;
• intrusion of the maxillary incisors and final levelling of the curve of Spee;
• settling and detailing of the occlusion; and
• optimisation of facial aesthetics and lip competence.

Follow-up

At the 16-month follow-up, the occlusion and alignment remained stable. The patient had been instructed to wear Essix retainers full time for six months, followed by lifelong night-time wear. Overjet, overbite and intercuspation remained unchanged, and facial aesthetics were preserved.

Conclusion

This case illustrates that, in selected growing patients, a carefully planned two-phase aligner-based approach combined with Class II elastics can effectively manage skeletal Class II, Division 1 malocclusion without extractions or functional appliances. Sagittal correction was achieved through a combination of mandibular advancement and controlled dentoalveolar movements, while vertical control prevented worsening of the overbite.

Beyond occlusal correction, the treatment produced meaningful soft-tissue improvements, particularly in the lower facial third, including improved lip posture and reduced mento-labial groove depth. The results remained stable at follow-up, supporting the viability of aligner therapy as an interceptive and comprehensive treatment option in growing patients when appropriately indicated.