A 26-year-old man had chief complaint of a long lower jaw. He denied any major systemic diseases or drug allergies. Clinical Findings
The clinical examination presented skeletal Class III relationship, retrognathic maxilla, excessive lower facial height and prognathic mandible with chin deviation to the left 3 mm. He had non-consonant smile arch without gummy smile. His lateral facial profile was concave with paranasal depression, acute nasolabial angle and shallow mentolabial fold (Figure 1)
His dental manifestation presented Angle's Classification III malocclusion with a negative overjet of -2 mm and overbite of 2.5 mm. The upper dental midline was 2 mm right to facial midline while the lower dental midline was 2 mm left to facial midline. For the maxilla, upper incisors were proclined (U1/SN=128.5°), mild crowding and right-side up occlusal plane canting. In contrast, the mandible presented spacing between canine and first premolar at both side with slightly retroclined lower incisors (L1/MP=85°) (Figure 2, Table 1)
From radiographic examination, all permanent teeth were erupted with 24 endodontically treatment. Average retropalatal and retroglossal and airway space, which was 9 mm and 12 mm respectively, were observed (Figure 3)
. Treatment goals and treatment plan
From the examination, the treatment goals were set.
| ||Treatment Goals|
- Correct facial proportion
- Correct lip posture
- Improve smile arch
- Correct midface deficiency and mandibular prognathism
- Correct maxilla canting
- Correct chin deviation
- Correct dental inclination and relationship
- Achieve Class I canine and Class II molar relationship
From the diagnosis and treatment goals together with patient's expectation, the treatment plan was performed with a modified surgery-first approach as following steps.
- General dental care: Full mouth scaling and polishing
- Presurgical orthodontic treatment: 14, 24 extraction for reducing incisal proclination, alignment and levelling.
- Orthognathic surgery:
Maxilla: 2-pieces LeFort I osteotomy
Mandible: Köle procedure and BSSO for mandible setback and asymmetry correction.
Genioplasty: chin contouring
- Post-surgical orthodontic treatment
In the maxilla, the significant maxillary crowding was relieved by 14 and 24 extractions while partially retracting the maxillary incisors to reduce the incisal proclination. Then, the upper incisors inclination was furtherly corrected more by a 2-pieces LeFort I osteotomy and closure of the 14, 24 residual dental space during surgery.
In the mandible, the lower dental spacing was caused by general tooth size and jaw bone discrepancy with relative upright incisal inclination. The presurgical preparation included consolidation the dental space distal to the bilateral mandibular canines. The presurgical orthodontics preparation took 7 months before surgery.
Then, the pre-operative records were taken included dental radiographs, cone beam computed tomography (CBCT) and surgical models. For surgical plan, a 2-pieces LeFort I osteotomy were performed which was cut at the area between 13-15 and 23-25. Anterior maxilla portion was clockwise rotated which resulted in upper incisor setback 4 mm, downward 1 mm and decreasing their inclination. The posterior portion of maxilla was moved forward for space closure and posterior impacted for further dental occlusion.
The bilateral sagittal split osteotomies (BSSO) were conducted for mandible setback and asymmetry correction. The mandible was set back 8mm at the right side and 5mm at the left side. Additionally, the subapical osteotomy with Köle procedure was applied with 2mm setback at the right side and 4mm setback at the left side. This procedure helped closing the dental space in the mandibular arch while keeping the anterior teeth in relative normal inclination. The excessive chin prominence caused by the Köle procedure was reduced by reduction genioplasty and surface contouring (Figure 4)
Post-operative orthodontic treatment took about 19 months included overbite control and detailing of the occlusion and interdigitation. Treatment Results
After treatment, patient's profile was improved to straight facial profile, symmetry and good facial proportion. All surgical segments were stable. Class I canine relationship and Class II molar relationship were achieved with 2 mm overjet and 2 mm overbite. The maxillary incisors proclination were improved, all the dental spaces were closed and well interdigitation (Figure 5, Table 1)
From the superimposition, the mandible was setback and the maxilla was clockwise rotated by impaction of posterior segment upward 3 mm. The pogonion point was moved backward by 7 mm along with posterior airway reduction to 8 mm at retropalatal and retroglossal area (Figure 6)
This case report was approved by the Institutional Review Board and Medical Ethics Committee of Chang Gung Memorial Hospital (No. 201900284B0).
Post-treatment photographs at the time of debond (19 months after surgery). View Hi-Res Image