관골하능 미니플레이트를 이용한 골격성 II급 성인 구순 돌출 환자의 비발치 교정 치료: 4년 경과 관찰

Abstract

Patients with skeletal Class II malocclusion often present with lip protrusion, lip incompetence and excessive activation of the mentalis muscle. Conventional orthodontic treatment typically involves the extraction of four premolars to retract the anterior teeth and reduce lip protrusion. However, when additional extractions are not feasible due to previous premolar extractions or congenital tooth agenesis, alternative treatment approaches are required. In this case, we report the successful treatment of a 28-year-old patient with lip protrusion and a history of previous orthodontic treatment with premolar extraction. Due to the absence of four premolars, further extractions were not an option. Instead, maxillary third molars were extracted, and miniplates were placed in the infrazygomatic crest to provide skeletal anchorage for total distalization of maxillary dentition. The miniplates allowed for efficient distalization of the maxillary dentition without the need for replacement tooth movement, which is often required with buccally placed inter-radicular miniscrews. After 33 months of orthodontic treatment, a Class I molar and canine relationship was achieved and the patient’s lip protrusion was significantly reduced. Cephalometric analysis confirmed 3 mm of maxillary molar distalization with a significant decreased incisor proclination. Four-year follow-up showed stable occlusion and soft tissue profile with no significant relapse. This case demonstrates the efficacy of infrazygomatic miniplates for full arch distalization in cases where additional extractions are not possible, providing long-term stability and improved esthetics.