61 陳長佑 / Chang-Yu Chen
Main Instructor I-Tsen Weng
Department / Institution Orthodontic Department of Wan-Fang Medical Center, Taipei, Taiwan
Classification case report
The characteristics of bimaxillary protrusion are malocclusion with dentoalveolar flaring of both the maxillary and mandibular anterior teeth causing protrusion of the lips and a convex facial profile. Patients with bimaxillary protrusion are also often accompanied by lip incompetence, mentalis strain, gummy smile, and anterior open bite. Lip incompetence and gummy smile are not necessarily caused by dentoalveolar flaring alone. Lip incompetence can be due to maxillary vertical excess, having a short upper lip, or incomplete passive crown eruption. Orthodontists must evaluate individual physical sequelae as there might be separate or coexisting problems that require further treatment.
Skeletal pattern: Class II relationship with mandibular retrognathsim; low mandibular plane angle
Dental pattern: Angle Class I malocclusion; bimaxillary protrusion
This case report describes a 18-year-old female asking for improving her protrusive lip and flaring anterior teeth. Clinical extra-oral examination revealed protrusive lips, lip incompetence, and an acute nasolabial angle. The treatment was extraction of four first premolars with maximum anchorage. Upper extraction space was closed with a 2-stage retraction, and lower extraction space was closed with En masse retraction. Two TADs were inserted at bilateral infrazygomatic crests of second molar for anchorage control. The deepened bite during space closure was solved by an intrusive arch at the lower arch. The results showed improved facial profile and a harmonized smile arc.
The TADs placed in infrazygomatic crests of second molars are proved to be efficient to intra-oral anchorage reinforcement and to anterior vertical control. Intrusive arch was also helpful in solving the deepened bite during space closure.
Angle Class I Malocclusion with Bimaxillary Dentoalveolar Protrusion– A Case Report