Diagnosis and Etiology
A 16-year-old girl presented at the outpatient department of our hospital with a chief complaint of an inability to bite with her front teeth. Given the lack of contact of the anterior teeth with each other, she was deemed to have articulation impairment and masticatory disturbance. Facial photographs showed a symmetrical face, a convex profile and a long lower facial height. She also had an obtuse nasolabial angle and no lip seal (Fig. 1A).
The mandibular dental midline was deviated 1.5 mm toward the right compared with the maxilla, and the occlusal plane was canted (Fig. 1A). Although the stability of the mandibular position in occlusion was slightly flexible, a Class I relationship was observed at the centric occlusion bilaterally. Her overjet was 9.0 mm, and her anterior open bite was 9.5 mm. There was severe crowding in the maxillary and mandibular arch, and their arch length discrepancies were − 10.7 and − 12.6 mm, respectively (Fig. 1B). The cephalometric analysis showed a skeletal Class II jaw-base relationship, a high mandibular plane angle, normal maxillary incisor positioning and proclined mandibular incisors (Fig. 2A and Table 1) [12]. The posteroanterior cephalogram showed that the center of the maxillary and mandibular arch accorded with the facial midline (Fig. 2B). The panoramic and periapical radiographs showed a shortened root for all incisors and canines (Fig. 2C and D). In addition, a panoramic radiograph showed that all third molars were impacted (Fig. 2C). A six-degrees-of-freedom jaw movement recording system showed that short-range movements of the incisal path were observed during maximum open-close jaw movements because of her severe open bite (Fig. 3A).
Table 1
| | | Japanese norm (adult) | Pretreatment | Posttreatment | Postretention |
| Mean | SD |
| Angular (° ) | | | | | |
| | ANB | 2.8 | 2.4 | 7.5 | 5.0 | 5.5 |
| | SNA | 80.8 | 3.6 | 73.5 | 74.5 | 74.5 |
| | SNB | 77.9 | 4.5 | 66.0 | 69.5 | 69.0 |
| | U1-FH | 112.3 | 8.3 | 113.5 | 110.0 | 110.0 |
| | L1-FH | 56.0 | 8.1 | 35.5 | 53.0 | 52.5 |
| | L1-Mp | 93.4 | 6.8 | 87.5 | 80.5 | 80.5 |
| | Mp-FH (FMA) | 30.5 | 3.6 | 57.0 | 46.5 | 47.0 |
| Linear (mm) | | | | | |
| | Overjet | 3.1 | 1.1 | 9.0 | 3.0 | 2.5 |
| | Overbite | 3.3 | 1.9 | -9.5 | 1.5 | 0.5 |
| | Ar-Go | 47.3 | 3.3 | 71.0 | 77.5 | 77.5 |
| | Ar-Me | 106.6 | 5.7 | 112.0 | 113.5 | 113.5 |
Treatment objectives and alternative options
Based on these findings, the patient was diagnosed with skeletal open bite malocclusion, a skeletal Class II jaw-base relationship and severe crowding with shortened roots.
Since the treatment objectives were to correct the skeletal deformity causing open bite and obtain ideal occlusion and the patient was already fully grown, the ideal treatment was a combination of surgery and orthodontic therapy. Four-piece LeFort I maxillary advancement osteotomy with differential impaction of the posterior segment and positioning of the anterior segment were planned to correct the open bite and maxillary incisor display. After autorotation of the mandible, bilateral sagittal split osteotomy and genioplasty could be considered to correct the open bite and long face. All impacted third molars were to be extracted before surgery so as not to interfere with the surgical procedures.
Another option was camouflage orthodontic treatment using miniscrew anchorage for the intruding maxillary and mandibular molars. An improvement of the anterior open bite could thus be obtained by the autorotation of the mandible. However, this approach would not be able to sufficiently improve the open bite and long face, which were severe skeletal deformities. Furthermore, it was feared that the shortened root of the incisors might be exacerbated by excessive tooth movement. To manage these issues, we decided to perform a combination of surgery and orthodontic therapy to improve both the dentofacial morphology and stomatognathic functions.
Treatment progress
After extraction of all canines, 0.018×0.025-inch preadjusted edgewise appliances were bonded to both arches, except for the maxillary incisors. Leveling and alignment were started with 0.016-inch heat-activated nickel-titanium wires for the maxilla and mandible, respectively. After performing leveling and alignment for 7 months, 0.018-inch preadjusted edgewise appliances were bonded to the maxillary incisors. The initial alignment was achieved with 0.016-inch heat-activated nickel-titanium wires. Subsequently, tooth alignment was performed by changing the archwires sequentially, and 0.016×0.022-inch stainless steel wires were used to adjust the tooth positions before surgery. The mandibular canines were extracted in order to improve the severe crowding and the missing canines were substituted with first premolars (Fig. 4). All third molars were extracted during leveling and alignment six months before surgery.
After presurgical orthodontic treatment for 1 year 10 months, 4-piece segmental LeFort I osteotomy combined with posterior horseshoe-like osteotomy was performed (Fig. 5). Maxillary osteotomy was achieved with posterior intrusion of 4.5 mm and advancement of 2.0 mm at the level of the first molars. Sagittal split ramus osteotomy (SSRO) of the mandible was performed with counterclockwise rotation and advancement of 10.0 mm at B point. Genioplasty was performed with advancement and intrusion of 4.0 mm each. Following osteotomy, the maxillary anterior segment was repositioned practically unchanged and connected to the mandible with appropriate overjet.
In the postsurgical orthodontic treatment, 0.016×0.022-inch stainless steel wires were installed to induce space closure of the maxillary dental arch spaces. Postsurgical orthodontic treatment was performed for 9 months. Detailing was initiated with 0.016×0.022-inch stainless steel wires in both arches, and then the edgewise appliances were removed. The total active treatment period was 2 years 11 months. The maxillary and mandibular wrap-around retainers were placed, and the patient was followed for two years.
Treatment results
The treatment induced impaction of the maxillary posterior pieces and the counterclockwise rotation of the mandibular segment, which subsequently improved the patient’s facial profile and incompetent lip seal (Fig. 6A). The AOB and severe crowding were improved, and an adequate overjet and overbite were achieved. Class I molar relationships were obtained (Fig. 6B).
On an evaluation of the jaw movements after treatment using a jaw-movement recording system with six-degrees-of-freedom, increases in the range of the maximum open-close jaw movements were observed. Furthermore, the condylar movement was maintained on both sides after orthodontic treatment (Fig. 3B).
The posttreatment cephalometric evaluation showed a decrease in the ANB angle, and a skeletal Class I jaw relationship was achieved (Fig. 7A, Table 1). The surgical changes in hard tissue resulted in maxillary advancement, posterior impaction and anterior segment repositioning as well as the subsequent mandibular counterclockwise rotation. The posterior segment of the maxilla eventually demonstrated intrusion of 4.5 mm and advancement of 2.0 mm.
The mandible was also set forward about 15 mm at the pogonion by SSRO and genioplasty. A posteroanterior cephalogram showed that the maxillary and mandibular midline coincided with the facial midline (Fig. 7B). A significant change in the maxillary incisor inclination was not shown, indicating that the relevant incisor inclination had been maintained (Fig. 8, Table 1). Suitable root paralleling was observed on a panoramic radiograph (Fig. 7C). The posttreatment panoramic and periapical radiographs showed no remarkable apical root resorption or alveolar bone loss (Fig. 7C, D).
The duration of active orthodontic treatment was 2 years 11 months. After two years of retention, although the cephalometric analysis showed a slight extrusion of the mandibular molars and clockwise rotation of the mandible, an acceptable facial profile and occlusion were maintained (Fig. 9–11, Table 1). The patient was satisfied with the treatment results.