1
Department of Orthodontics, China Medical University and Medical Center, Taiwan, R.O.C,
2
School of Dentistry, College of Dentistry, China Medical University, Taiwan, R.O.C,
Corresponding author details:
Jian-hong Yu PhD, Professor of School of Dentistry
College of Dentistry Dean of Department of Orthodontics
China Medical University and Medical Center
R.O.C,
Copyright:
© 2018 Huang CS, et al. This is
an open-access article distributed under the
terms of the Creative Commons Attribution 4.0
international License, which permits unrestricted
use, distribution, and reproduction in any
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are credited
In this case, ISW (improved superelastic Ti–Ni alloy wire, commonly called a lowhysteresis wire, developed by Tokyo Medical and Dental University) was employed in
the treatment of an adult facial asymmetry skeletal Class III case without extraction and
surgery. A 23-year-old man came to our clinic with a chief complaint of poor bite and for
esthetic consultation. A clinical examination revealed a bilateral Class III molar relationship
with anterior crossbite and mild crowding with a lower midline deviated to the right. Active
treatment included establishment of a crossbite arch in the upper arch by using an ISW
without extraction and removal of the lower-right fixed bridge prosthesis. Using ISW and
adequate Class III intermaxillary elastic traction meant that the malocclusion was corrected
with a minimal orthodontic approach. Treatment was completed within 19 months, and a
stable occlusion was achieved after the active treatment.
Correct differential diagnosis of skeletal, functional, and dental anterior crossbite malocclusion has always been critical in clinical practice. The limitation of dental compensation includes the surrounding bone quantity and level. Nonextraction treatment of Class III malocclusion in adult patients usually requires distal movements of the mandibular molars to establish Class I molar and canine relationships [1-3].
The patient was a 23-year-old Taiwanese man at the time of his initial visit. He came with a chief complaint of poor bite and for esthetic consultation regarding the upper anterior teeth. His profile was concave, and the frontal view showed facial asymmetry (Figures 1 and 2). His occlusion exhibited a bilateral Class III molar relationship and a Class I canine relationship. He presented with an anterior crossbite (overjet −4.0 mm), a deep bite (overbite −3.5 mm), and a lower midline deviation to the right side (2.0 mm). Upper and lower anterior dentition revealed mild crowding. Oral hygiene and gingival conditions were normal.
Cephalometric analysis showed a skeletal Class III jaw relationship (Figure2, Table 1). The patient had a combination of a prognathic mandible and retrognathic maxilla (SNA 88.8º, mean 81.82º; SNB 90.5º, mean 78.61º; ANB −1.8º, mean 3.28º). Vertically, he presented a short face, that is, a hypodivergent skeletal pattern (Frankfort-mandibular plane angle [FMA] 21.0º). Because he had an upper anterior crossbite, the interincisal angle was large at 139.6º, and the occlusal plane was relatively small (0.9º) due to the functional anterior crossbite. A temporomandibular joint (TMJ) radiograph showed no apparent irregularity over the condylar head (Figure 3). The diagnosis was skeletal Class III malocclusion with facial asymmetry. If the patient had preferred a full-mouth tooth alignment arrangement, the lower-right fixed prosthesis would have had to be removed (Figure 4).
A summary of the diagnosis is as follows:
1. Functional (+): anterior crossbite
2. Skeletal (±): ANB = −1.8 º, skeletal Class III tendency
3. Denture (+): upper incisor (UI) to Frankfort horizontal (FH) plane (109.7°)
4. Dental (+): existence of #38
5. Discrepancy (+): upper: right: −4.0 mm, left: −6.0 mm :
lower right: −3.0 mm, left: −4.0 mm
The treatment plan included the following steps:
1. Extraction of #38
2. Full-mouth DBS (Direct bonding system) and leveling
3. Correction of the anterior crossbite using a crossbite arch
4. Confirmation of the mandibular position; long Class III IME
traction to camouflage the esthetic concern
Figure 1: Pretreatment photographs and models (23 years 8 months old).
Figure 2: Pretreatment lateral and PA (postero-anterior) cephalometric radiographs (23 years 8 months old).
Table 1: Cephalometric Comparison
Figure 3: Pretreatment TMJ radiographs.
Figure 4: Pretreatment panoramic radiographs.
ISW was used for management of the 23-year-old patient presenting with functional anterior crossbite and facial asymmetry with maxillary and mandibular anterior dental crowding. The treatment objective was to achieve an ideal occlusion of the bilateral angle’s Class I canine and molar relationship.
Our treatment objectives were (1) to improve the patient’s
facial profile, (2) to improve the skeletal jaw relationship as much
as possible by removing the occlusal interference of the functional
anterior crossbite and redirecting the change of mandible position
in a downward, backward direction, (3) to accomplish desirable
anterior occlusion for establishing functional occlusion, (4) to correct
the midline deviation, and (5) to follow up the retention to assess the
need for further treatment.
Because of the patient’s functional disharmony, we explained to him the high possibility of jaw movement if the functional interference of the anterior crossbite was removed. Also, bilateral upper first bicuspid extraction was possible if the patient had concerns about a protruding esthetic, as well as the possibility of removing the lowerright fixed prosthesis to correct the occlusal interference that was causing the mandibular shift, forming an asymmetrical facial profile [10]. We also informed him of the possibility of a surgical approach if he had a strong desire for profile improvement. The treatment alternatives included either extraction or nonextraction of the upper bicuspid, depending on the patient’s expectations of profile improvement. Because the patient preferred nonextraction, we thoroughly explained that if correcting the upper anterior crowding and crossbite resulted in further (subjective) concern of a protruding profile, extraction of the upper bicuspid would be an option during subsequent treatment.
Because IME traction could not be used over the lower dentition because of the lower-right fixed prosthesis, mandibular clockwise rotation would only contribute from if the upper molars were extruded. Mandibular clockwise rotation would enhance the reduction of the anterior overjet and offer improved vertical control; furthermore, because the patient preferred nonextraction and was unwilling to remove the lower-right fixed prosthesis, the treatment could only be accomplished by reassessing the treatment response regarding the correction of facial asymmetry and by using the ISW crossbite arch to tentatively remove the interference caused by the functional anterior crossbite.
Moreover, the patient strongly preferred nonextraction and
nonsurgical treatment.
Treatment started on February 12, 2014, with upper arch DBS and leveling with a 0.016-inch × 0.022-inch L&H Titan Wire (ISW) (Tomy International Inc., Tokyo, Japan) for relief of anterior crowding (Figure 5).
On May 16, 2014, the crossbite arch was set between #13 and #23 to correct the anterior crossbite (with crimpable stoppers placed mesial to the bilateral upper canines to form a central omega loop) (Figure 6). Also, Class III IME traction was used to raise the bite and to adjust the jaw relationship.
On July 9, 2014, after 5 months of active treatment, the anterior crossbite was corrected (Figure 7). The anterior teeth reached an edge-to-edge relationship using an open coil spring for creating space between #21 and #23, an elastic chain for correcting the upper midline, and IME traction for Class III jaw relationship correction.
Soon afterwards, derotation of #22 was performed, and on August 20, 2014, re-DBS of #22, #31, and #35 was applied and an elastic chain for correcting the lower midline was fitted (Figure 8).
On January 12, 2015, after 5 months, derotation was completed through re-DBS of #12, #11, and #21 and upper and lower leveling with a 0.016-inch × 0.022-inch ISW (Figure 9). The periodontal condition of #22 was confirmed by using periapical radiography (Figure10).
On March 16, 2015, panoramic radiography was used for reconfirmation, and re-DBS of #22, #32, #35, #43, and #44 was performed for ideal root parallelism to achieve more accurate root parallelism adjustment (Figure 11 and 12).
Finally, on June 10, 2015, an elastic chain for midline correction
and right (3-3) and left (3-3) IME traction were used to consolidate the
canine relationship and for final finishing and detailing (Figure13).
Figure 5: Intraoral photos of the beginning of active treatment
Figure 6: Intraoral photos of 3 months of active treatment.
Figure 7: Intraoral photos of 5 months of active treatment.
Figure 8: Intraoral photos of 6 months of active treatment.
Figure 9: Intraoral photos of 11 months of active treatment.
Figure 10: Periapical film of #22 of 15 months of active treatment.
Figure 11: Intraoral photos of 13 months of active treatment.
Figure 12: Panoramic film of 13 months of active treatment.
Figure 13: Intraoral photos of 16 months of active treatment.
On September 16, 2015, after 19 months of active treatment, debonding of the bracket was performed, and a circumferential retainer was placed in the upper arch and a Hawley retainer in the lower arch (Figure14).
Active treatment was completed within 19 months, and a stable occlusion was achieved. After 19 months of active treatment, including 18 months of multibracket appliance treatment, the anterior crossbite and facial asymmetry were corrected and a normal functional occlusion was established (Figure 15).
The patient’s profile had markedly improved, and the mandibular deviation had been corrected. A cephalometric superimposition (Figures 16 and 17, Table 1) showed that the anteroposterior relationship had improved (ANB −1.8˚→ −1.3˚). The UI had tipped labially (UI to FH plane 109.7° → 128.1°), with the SNA reduced (SNA 88.8˚ → 86.8˚). Because of the upper molar extrusion, the mandibular plane was camouflaged by a downward and backward clockwise rotation of the mandible (FMA 21.9˚ → 23.2˚).
The anterior overbite and overjet was ideal because of (1) the change in the lower incisor (LI) to the mandibular plane (88.8˚ → 90.2˚) and (2) the change of the FMA angle, but mostly because of the correction of the anterior crossbite resulting from (3) the change of U1 to the FH plane angle (109.7˚ → 128.1˚) (Figure 18). The interincisal angle was reduced and compensated mostly by the tooth movement of the UIs (U1 to FH plane angle change 18.4˚/2.5˚ = 7.36 mm change in the anterior overjet).
In the panoramic view, the root parallelism was excellent, and no
apparent root resorption was found (Figure 12). A 2-year follow up
(the patient was 27 years old) showed that he had a balanced esthetic
profile and occlusion, and he was pleased with the result (Figure 19). A
comparison of the post-treatment (25 years and 5 months) and 2-year
retention (27 years and 5 months) cephalograms (Figure 20, Table 1)
illustrates stable dentoalveolar and maxillomandibular relationships.
Figure 14: Intraoral photos of 19 months of active treatment.
Figure 15: Posttreatment photographs and models (25 years 5 months old).
Figure 16: Posttreatment lateral and PA (posterior-anterior) cephalometric radiographs (25 years 5 months old).
Figure 17: Superimposition of cephalometric tracings before (black line) and after (red line) treatment.
Figure 18: Anterior overjet correction results mostly from the change of U-1 to FH plane after treatment (blue arrow indicated the
U1 tip movement).
Figure 19: Posttreatment photographs and models at 2-years follow-up (27 years 5 months old).
Treatment using ISW crossbite arch to correct the anterior crossbite without extraction and surgery for the correction of facial asymmetry was critical in this case. The crucial part of the upper anterior crowding and the upper anterior crossbite caused further esthetic concern in the patient because of the demand of the upper anterior to flare out (tipping).
For a patient whose growth spurt had already passed, controlled tipping among the upper anterior teeth was considered vital. Without the expansion of the middle dentition and distalization of the posterior teeth, correcting the anterior crossbite was performed mainly through flaring out the anterior teeth, with the space also used for the derotation of the anterior teeth. Upper left lateral incisor derotation combined with the long Class III IME traction was adopted to reduce the over jet. For Ti–Ni wires such as ISW, friction control between the surface of the bracket slot and arch wire is paramount [11].
Differentially diagnosing a Class III case using dental, functional, or skeletal indicators is critical before active treatment. This case showed slight facial asymmetry, crowding over the anterior crossbite region, and the presence of a unilateral prosthesis in the lower-right portion. After 19 months of treatment, interdigitation was improved, and with the use of Class III IME, the anterior crossbite was corrected easily. Finally, a desirable esthetic outcome was achieved and the patient was pleased with the result. The discussion is continued in four categories.
Midline control after the anterior crossbite was corrected deviated to the left side because of palatal tipping of the right lateral incisor, resulting in inadequate horizontal clearance; therefore, 1 month after the first crossbite arch (between #11 and #21) was applied, a second crossbite arch was used to effectively correct the anterior crossbite in the upper-left region. Discrepancy over the upper-left anterior teeth was larger because #22 required derotation. Eliminating the lower anterior teeth occlusal interference included either not-in-slot over the lower anterior teeth or labial tipping over the lower anterior teeth (creating a horizontal clearance for the limited bracket bonded space of the upper anterior teeth).
Figure 21: Progress in crossbite correction.
Figure 22: Smile arc consideration.
Figure 24: Pharyngeal airway and hyoid bone.
Friction control of Ti–Ni wires is critical in ISW treatment
philosophy. Esthetic concerns should be critical when correcting an
anterior crossbite, when derotating the upper-left lateral incisor, in
torque control of the upper anterior teeth, and in appropriate IME
traction for achieving an adequate anterior overjet [13-18]. Because
the lower-right prosthesis was not included in the orthodontic tooth
movement, distalization and space creation for the posterior part of
the lower arch could not be achieved. Before the active treatment,the patient already had a favorable lateral/posterior over jet. The
anterior crossbite was corrected and a suitable anterior overbite
and over jet was achieved mainly due to favorable upper anterior
torque control and IME traction. Because of the patient’s mid face
concave profile, the flaring out of the upper anterior teeth improved
the patient’s divergent profile and enhanced the flaring effect of
the lower anterior teeth. The active treatment included a crossbite
arch in the upper arch by using ISW without extraction or removal
of the lower-right fixed bridge prosthesis (using a Ti–Ni alloy ISW
and adequate Class III IME traction). Consequently, the malocclusion
was corrected using a minimal orthodontic approach. Treatment was
completed within 19 months, and a stable occlusion was achieved
after the active treatment.
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