Combined orthopedic-orthodontic treatments of adolescent skeletal open-bite with severe molar-incisor hypomineralization: a case report and literature review

The treatment of adolescent skeletal open-bite malocclusion with severe molar-incisor hypomineralization (MIH) remains challenging. Though conducive to open-bite treatment and endodontic management, early molar extraction may trigger a series of negative impacts on occlusion and stomatognathic development. In addition, molars' crown restoration was shown to worsen open-bite malocclusion considering the intrinsic vertical increment of hyperdivergent growth. This case report describes the successful multidisciplinary therapy combined with orthopedic and orthodontic treatment of a 10.2-year-old girl with mixed dentition, a protruding profile and skeletal open-bite malocclusion with severe MIH and crowding. During the mixed and early permanent dentition, function regulator-4 (FR-4), resin-bonding transpalatal arch (TPA) and modified spring-loaded bite blocks were implemented to correct abnormal swallowing and control the facial vertical growth. Radiographic results, including the counterclockwise rotation of the occlusion plane, decreasing mandibular angle and increasing posterior-anterior face height ratio accompanied by obvious mandibular vertical growth, indicated that the performed orthopedic treatments efficiently controlled hyperdivergent open-bite growth during puberty. After the maxillary and mandibular second molars were occluded, all first permanent molars were extracted, and fixed appliances combined with implant anchorage were used to correct malocclusion and convex profile. Ultimately, a stable Class I functional occlusion and satisfying facial improvement were achieved and maintained following a 2-year follow-up.