Prognosis of Class II Division 1 Deep Overbite Treated by Extracting the Unilateral Jaw Side Teeth

Abstract

Maxillary protrusion with deep overbite due to undergrowth of the mandible and labial inclination of maxillary incisors was orthodontically treated by extracting the teeth in 5⊥4, and overcorrecting overjet and overbite. Although continuous prevention of periodontal disease, use of retainers, and instructions regarding lip biting habit had been performed, increases in overbite were noted two years after the initiation of retention. Even in cases with deep overbite, if stable tooth contact in the centric occlusion is present without functionally harmful actions, problems will not occur. However, if load is excessively applied to the temporomandibular joint and adverse actions on the periodontal tissue are caused due to anterior and lateral sliding movement restriction, the condition is not stable. In this case, since the mandibular angle was skeletally small, and the maxillary and mandibular canines, the lateral incisors, showed marked attrition, it was predicted that the masticatory pattern was excessive grinding. These functional problems were caused by decreases in the width between the mandibular canines, extrusion and lingual inclination of the mandibular anterior teeth, and the extrusion of the maxillary anterior teeth, resulting in the maxillary anterior teeth being pushed upward by the mandibular anterior teeth. This causes median diastema and an increase in overbite, an unstable condition. Therefore, it is suggested that, to prevent the relapse of overbite in deep overbite cases, not only overcorrection of the overjet and overbite, but also the establishment of more precise and stable quantitative treatment goals considering the mutual relationship among function, occlusion and morphology is important.