Abstract:

Angle class Ⅱ malocclusion is often characterized by mandibular retraction and lip incompetence， which affects the patient’s lateral appearance and may even lead to upper airway stenosis. It can be classified into dental and skeletal types. For skeletal class Ⅱ malocclusion patients with mandibular retraction during the peak growth period， mandibular anterior guidance with a functional orthodontic appliance is generally considered as the optimal clinical treatment approach. At present， there remains a paucity of clinical reports on the clinical application of bracket-free clear aligners in mandibular anterior guidance， both domestically and internationally. This article presented a case of an adolescent patient with skeletal class Ⅱ malocclusion accompanied with deep overbite treated with bracket-free clear aligner for mandibular anterior guidance in combination with intermaxillary class Ⅱ traction. During the treatment， vertical correction involved anterior intrusion of the anterior teeth to improve the deep overbite， while horizontal correction included maxillary and mandibular expansion to coordinate the width of the dental arches，and asymmetric anterior guidance was used to correct the midline deviation. After 35 months of treatment，the patient’s convex facial profile and mandibular retrusion were significantly improved. The subspinale-nasion-supramentale angle （ANB） was decreased from 6.8° to 3.9°， the overbite and overjet were normalized， and the bilateral canine and molar reached a neutral relationship. The mentolabial sulcus depth （Si-LiPg'） and the soft tissue thickness of pogonion to pogonion （Pm-Pm'） were decreased，resulting in a shallower mentolabial sulcus and a more harmonized lateral facial soft tissue profile. The mandibular incisor to mandibular plane angle （IMPA）was decreased from 116.6° to 110.7°， indicating retraction of the lower incisors during mandibular anterior guidance. In conclusion， the orthodontic strategy of mandibular advancement with clear aligners in skeletal class Ⅱ malocclusion patients can avoid excessive overcompensation of the upper and lower anterior teeth and shorten the orthodontic treatment cycle.

Key words: Orthodontic treatment, Angle class Ⅱ division 1 malocclusion, Skeletal class Ⅱ malocclusion, Mandibular advancement, Bracket-free clear aligner therapy