A 7-year-old boy had been mocked by his classmates for having irregular upper anterior teeth for half a year and sought medical attention. He had a history of mouth breathing for about 2 years. A thorough general examination was carried out to rule out the presence of any syndrome. Medical and family histories were non-contributory. Extra-oral examination revealed a convex soft tissue shape and mandibular hypoplasia (Fig. 1A–C). Intra-oral examination showed mixed dentition, which was normal for the boy’s age. In the anterior region of the maxilla, there was severe torsion of the anterior teeth (Fig. 1D–H). Teeth 11 and 21 displayed mesial 90° rotation, with about a 10-mm gap between them; the upper central incisors were located in the interproximal space between the lower central incisors and lateral incisors at the central occlusion; there was visible plaque + +; 31, 32, 41, and 42 gums were congested; and 41 gums were slightly retracted.
Periapical radiographs, a panoramic X-ray, a lateral cephalogram, and cone-beam computed tomography (CBCT) were performed. On X-ray, teeth 11 and 21 displayed about mesial 90° rotation (Fig. 2). The right supernumerary tooth was horizontally impacted and the crown was located on the palatal side, about 2 mm from the alveolar ridge. The left supernumerary tooth was parallel to the long axis of tooth 21 and was erupted submucosally. The lateral cephalogram showed a sagittal class II skeletal malocclusion (∠ANB, 5.9°) with vertical growth type (S-Go/N-Me, 60.4 and ∠SN-MP, 41.6°) (Fig. 3 and Table 1).
Table 1
Cephalometric measurements
Measurement
|
Initial
|
Post-treatment
|
Normal
|
Standard deviation
|
SNA (°)
|
74.6
|
74.8
|
83.0
|
4.0
|
SNB (°)
|
68.6
|
69.9
|
80.0
|
4.0
|
ANB (°)
|
5.9
|
4.9
|
3.0
|
2.0
|
FMA (FH-MP) (°)
|
28.9
|
28.4
|
26.0
|
4.0
|
Y-axis (°)
|
62.9
|
63.2
|
64.0
|
2.0
|
SN-MP (°)
|
41.6
|
41.3
|
30.0
|
6.0
|
S-Go/N-Me
|
60.4
|
59.9
|
64.0
|
2.0
|
U1-SN (°)
|
99.1
|
92.0
|
106.0
|
6.0
|
U1-NA (°)
|
24.5
|
17.2
|
23.0
|
5.0
|
U1-NA (mm)
|
3.5
|
2.1
|
5.0
|
2.0
|
U1-L1 (°)
|
120.1
|
128.4
|
124.0
|
8.0
|
FMIA (L1-FH) (°)
|
51.9
|
53.5
|
55.0
|
2.0
|
L1-NB (°)
|
29.5
|
29.5
|
30.0
|
6.0
|
L1-NB (mm)
|
5.7
|
7.2
|
7.0
|
2.0
|
Z-angle
|
54.7
|
56.8
|
77.0
|
5.0
|
FH-N’Pg’
|
81.0
|
83.0
|
85.0
|
3.0
|
N’-Sn-Pg’
|
159.4
|
159.3
|
168.0
|
4.0
|
The diagnosis of this patient was as follows: 1) Angle class II with severe rotation of the upper central incisors, 2) sagittal type II, 3) vertical osteofacial pattern, 4) mild crowding of the upper dentition, 5) soft tissue convex, 6) early stage of growth and development, 7) supernumerary teeth at the maxillary midline, 8) plaque gingivitis, and 9) 41 gingival recession (occlusal trauma). The following treatment plan was developed: 1) preoperative ear, nose, and throat (ENT) consultation to exclude the possibility of obstructive lesions in the nasal airway, 2) extraction of supernumerary teeth, 3) orthodontic alignment of maxillary dentition, 4) oral hygiene guidance, and 5) maintenance.
Before orthodontic treatment, the supernumerary teeth were extracted to create a space for the upper central incisors (Fig. S1). The ENT consultation found no abnormalities in the airway. The orthodontic treatment was sequential, starting with aligning the upper anterior teeth (Fig. 4A–E). An intra-maxillary casting distractor was designed, which was bonded to the lingual buckle on the twisted tooth and pulled with elastic wire traction using light force (< 60 g), rotationally moving the severely twisted tooth so that it became mildly-to-moderately twisted (Fig. 4F), and then using the transpalatal arch and maxillary 2×4 fixed orthodontic technique to align the maxillary incisors after 41 days (Fig. 4G). The initial arch wire was 0.012 thermal activation wire, which was replaced once every 2 months three consecutive times, followed by 0.014 thermal activation wire and 0.016 wire; for 2 years and 4 months after surgery, 12–22 "8" ligation was used (Fig. 4H–L), during this stage, mandibular without any treatment.
After aligning the upper anterior teeth, the next stage was to maintain and guide the establishment of normal occlusion. The child wore a Hawley retainer during the day, and a customized silicone guide, as well as lip patches to assist lip closure, at night (Fig. 5A–E). Five years after treatment, when the patient was 12 years old, a physiological occlusion was initially established, with a coordinated profile and no caries. The pulp vitality test of teeth 11 and 21 showed no abnormalities, the periodontal tissue was healthy, and the tooth class was improved. There was a positive anterior overjet, resolution of the anterior crossbite, and upper and lower alignment, but still a slightly distal relationship of the first permanent molar and II° deep overbite (Fig. S2A–J). Therefore, the patient continued to wear the customized silicone guide at night for a year, combined with strong chewing function. At the end of the maintenance phase, a physiological occlusion was established (Fig. 5F-O), with a molar and canine class I relationship, normal overjet and overbite, midline alignment, and no temporomandibular joint-related symptoms. From a cephalometric point of view (Fig. 6B and Table 1), the inclination of the upper incisors and mandibular retraction were improved, which resulted in esthetic and functional enhancement. Pre-post cephalometric evaluation is provided in Table 1 and cephalometric tracing superimposition is shown in Fig. 6C-D.