抄録
Deformities of the mandibular condyle, including hypoplasia and resorption, are often associated with severe open bite and mandibular retrusion. These conditions can lead to various functional and esthetic problems, such as masticatory dysfunction, speech impairment, facial esthetic concerns, sleep-disordered breathing, and temporomandibular joint dysfunction, all of which are closely linked to a reduced quality of life. In such cases, orthognathic surgery may be required to improve occlusion and facial appearance. However, treating skeletal Class Ⅱ open bite with condylar deformities presents significant challenges in achieving long-term stability. Condylar abnormalities can lead to instability of mandibular positioning during or after treatment, increasing the risk of open bite relapse and mandibular retrusion. Additionally, progressive condylar resorption following orthognathic surgery has been reported to further exacerbate open bite and mandibular retrusion. Therefore, when planning treatment for skeletal Class Ⅱ open bite with condylar deformities, a thorough evaluation of the temporomandibular joint （TMJ） and a strategic approach to ensure long-term stability are essential.
In typical cases of skeletal Class Ⅱ open bite, favorable occlusion and facial balance can be achieved through mandibular advancement and rotational adjustments of the maxilla and mandible. However, in cases with condylar abnormalities, the instability of mandibular positioning and the increased risk of postoperative condylar resorption necessitate special considerations for TMJ health during treatment planning. Increasing the amount of mandibular advancement to achieve an ideal facial profile places greater stress on the TMJ, elevating the risk of condylar resorption and relapse. Conversely, prioritizing postoperative stability requires a surgical approach that minimizes TMJ stress, which may result in suboptimal facial esthetics and reduced patient satisfaction. This creates a fundamental dilemma between “occlusal stability” and “facial esthetics,” posing a major challenge in treatment planning.
The present case involved a 16-year-old female patient with bilateral condylar hypoplasia without temporomandibular disc displacement, resulting in mandibular retrusion and hypoplasia, skeletal Class Ⅱ with a high-angle pattern, and anterior open bite with a two-plane formation in the maxillary anterior region. Soft tissue findings included marked lip incompetence, and a convex profile associated with severe chin retrusion. We applied a stabilization splint preoperatively to achieve a stable mandibular position, followed by surgical orthodontic treatment consisting of a two-piece Le Fort I osteotomy in the anteroposterior direction, bilateral sagittal split osteotomy （BSSO）, and genioplasty. As a result, a favorable soft tissue profile and occlusion were achieved. In this report, we describe the treatment approach, outcome, and key considerations for managing this case.
