Download Orthognathic treatment for a patient with Class III malocclusion and

CASE REPORT
Orthognathic treatment for a patient with
Class III malocclusion and surgically
restricted mandible
Marcos Janson,a Guilherme Janson,b Eduardo Sant’Ana,c Douglas Tibola,d and Décio Rodrigues Martinse
Bauru, Brazil
This case report describes the orthodontic-surgical treatment of an adult with Down syndrome and a Class
III skeletal malocclusion with posterior open bite, horizontal facial pattern, missing mandibular posterior
teeth, and surgical restriction of the mandible. (Am J Orthod Dentofacial Orthop 2009;136:290-8)
C
lass III malocclusion is a difficult anomaly to
understand. Studies conducted to identify the
etiologic features of Class III malocclusion
showed that the deformity is not restricted to the jaws
but involves the total craniofacial complex.1,2 Most
subjects with Class III malocclusions have combinations of skeletal and dentoalveolar components.3 The
factors contributing to the anomaly are complex. They
can act synergistically or in isolation, or they might
cancel each other.2
Treatment of skeletal Class III malocclusion in an
adult requires dentoalveolar compensation or combined
orthodontic and surgical procedures, with the aim to
achieve normal occlusion and improve facial esthetics.4-6
However, not every patient is amenable to all necessary
surgical procedures.7-10 Therefore, the objective of this
article is to present the treatment of a skeletal Class III
malocclusion in a patient with mild Down syndrome and
a horizontal growth pattern, absence of several posterior
teeth, hypertrophied musculature, and mandibular alveolar
bone reduction that restricted surgery in the mandible. The
dentoalveolar orthodontic compensation and surgical alternative are discussed.
a
Private practice, Bauru, Brazil.
Professor and head, Department of Orthodontics, Bauru Dental School,
University of São Paulo, Bauru, SP, Brazil.
c
Associate professor, Department of Oral and Maxillofacial Surgery, Bauru
Dental School, University of São Paulo, Bauru, SP, Brazil.
d
Graduate student, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, SP, Brazil.
e
Professor, Department of Orthodontics, Bauru Dental School, University of
São Paulo, Bauru, SP, Brazil.
The authors report no commercial, proprietary, or financial interest in the
products or companies described in this article.
Reprint requests to: Guilherme Janson, Department of Orthodontics, Bauru
Dental School, University of São Paulo, Alameda Octávio Pinheiro Brisolla
9-75, Bauru - SP - 17012-901, Brazil; e-mail, [email protected].
Submitted, January 2007; revised and accepted, January 2007.
0889-5406/$36.00
Copyright © 2009 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2007.01.039
b
290
DIAGNOSIS AND ETIOLOGY
An 18-year-old man with mild Down syndrome
came for orthodontic treatment at private orthodontic
office of Marcos Janson. His main complaint was
difficulty in chewing. He had a skeletal Class III
malocclusion with bilateral posterior crossbite, a
concave facial profile, and facial asymmetry (Figs
1-4 and Tables I and II) The absence of the mandibular right first and second molars and left first molar
aggravated his occlusal problems. In the mandible,
the left deciduous canine and the right third molar
and the left second and third molars were present.
The periodontal tissues were healthy.
TREATMENT OBJECTIVES
The treatment objectives were to surgically advance
and rotate the maxilla clockwise, retract and produce an
intrabasal clockwise rotation of the mandible to rotate
the occlusal plane, and correct the anterior and posterior crossbites. In addition, the maxillary and mandibular dental arches would be aligned, improving the
patient’s facial profile. In the mandible, extraction of
the right third molar, the left second and third molars,
and the left deciduous canine would also be necessary.
Dental implants would replace the missing mandibular
molars. These procedures would improve his chewing
efficiency.
TREATMENT ALTERNATIVES
Three alternatives were presented to the patient.
The first consisted of dental compensation by removing
the deciduous canine and closing the spaces with Class
III intermaxillary elastics. Although this approach
would correct the anteroposterior and transverse problems, it could compromise the posterior occlusion and
the smile line. Because of the missng mandibular
posterior teeth, the use of Class III elastics could
Janson et al 291
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 136, Number 2
Fig 1. Pretreatment facial and intraoral photographs.
aggravate the mandibular occlusal plane inclination,
worsening the posterior open bite. Moreover, the maxillary occlusal plane would rotate counterclockwise and
completely hide the maxillary anterior teeth.11-13
The second option included surgical advancement
and clockwise rotation of the maxilla, and mandibular
reduction with intrabasal clockwise rotation. This
seemed to be the best option to obtain the treatment
objectives. However, the absence of posterior teeth in
the mandible for many years caused severe resorption
and atrophy of dentoalveolar height and width, leaving
a thin residual basal bone. Additionally, the patient had
strong masticatory muscles and Down syndrome,
which caused some uncertainty about his compliance
with postoperative care.14,15
The third treatment option was to advance and
rotate the maxilla clockwise without surgical intervention in the mandible. Postsurgical orthodontic extrusion
of the mandibular premolars would be necessary to
reach the occlusal contacts. Because of the limitations
of the first 2 options, the patient and his parents chose
this alternative.
TREATMENT PROGRESS
Preoperative orthodontic preparation was performed
with conventional 0.022-in edgewise appliances. After
extraction of the mandibular left deciduous canine, leveling and alignment began with 0.016-in nickel-titanium
archwires, followed by 0.016-, 0.018-, and 0.020-in
stainless steel round archwires up to 0.019 ⫻ 0.025-in
rectangular archwires. In the leveling and alignment
stage, the archwires were coordinated, and the mandibular left permanent canine was moved to the deciduous
canine extraction space with an elastic chain on the
anterior teeth and an open-coil spring distal to the
canine (Figs 5 and 6). This procedure took 12 months.
After alignment and implant-site preparation, 0.019 ⫻
0.025-in stainless steel rectangular archwires were
placed in the maxillary and mandibular arches in
preparation for surgery. The surgery consisted of maxillary advancement to obtain a Class I occlusion and
proper overjet.
Postoperatively, since it was not possible to
rotate the mandibular plane, a posterior open bite
292 Janson et al
American Journal of Orthodontics and Dentofacial Orthopedics
August 2009
Fig 2. Pretreatment study models.
Fig 4. Pretreatment panoramic radiographic.
Fig 3. Pretreatment cephalometric tracing.
remained. To achieve the proper occlusal contacts,
vertical intermaxillary (1/8 in) and Class III elastics
(5/16 in) were used (Fig 7). The final occlusal
relationship was retained with a maxillary Hawley
plate and a mandibular canine-to-canine retainer. A
partial removable prosthesis was placed after treatment to rehabilitate the edentulous area. Osseointe-
Janson et al 293
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 136, Number 2
Fig 5. Intraoral photographs during treatment showing tooth movement to prepare site for implant
placement in area of newly formed alveolar bone, between the canine and the first premolar.
Fig 6. Presurgical intraoral photographs.
Fig 7. Postsurgical intraoral photographs showing vertical intermaxillary elastics for posterior
dentoalveolar extrusion.
grated implants were rejected by the patient’s parents
because a bone graft would be necessary, with increased
treatment costs.
RESULTS
The posttreatment photographs show improvement
in the facial profile and elimination of facial asymmetry
caused by the malocclusion. The patient was satisfied
with his teeth, profile, and smile line. The final occlusion showed a Class I canine relationship on both sides.
The maxillary right third molar and the mandibular left
second and third molars were not removed because of
the complexity of the procedure. The mandibular right
third molar was extracted (Figs 8-11).
In addition to maxillary protrusion, the maxillary
and mandibular incisors were labially tipped and
294 Janson et al
American Journal of Orthodontics and Dentofacial Orthopedics
August 2009
Fig 8. Posttreatment facial and intraoral photographs.
slightly protruded (Table II). The superimposition of
the cephalometric tracings show that the maxilla was
advanced with the orthognathic surgery, and the mandible experienced minimal counterclockwise rotation
and protrusion (Fig 12). A considerable reduction in the
nasolabial angle was observed. Facial concavity decreased, maxillary incisal exposure at rest was increased, and the lips were protruded.
The orthodontic tooth movement provided successful alveolar bone development in the horizontal and
vertical planes for implantation of 1 dental implant
distal to the mandibular left canine. Occlusal equilibration was performed after appliance removal to refine
the interocclusal contacts. Root resorption was minimal
(Fig 11).
DISCUSSION
The treatment protocol produced a satisfactory
occlusal and esthetic result for the patient and his
parents, as demonstrated by their attitude at the end of
treatment. Maxillary advancement provided good support for the upper lip, filled the soft-tissue midface, and
favorably improved the patient’s profile. Facial profile
change is important in syndromic patients, since 1
characteristic is a retruded midface.14,16 The surgical
advancement of the maxilla also provided a satisfactory
anteroposterior relationship with the mandible and
improved maxillary incisor exposure. Better dental
relationships also improved the functional mandibular
asymmetry on the left side that was caused by the
anterior and posterior crossbites (Fig 1).15,17
Ideally, mandibular surgery also should have been
performed to rotate the mandible clockwise, decreasing
the chin prominence and reducing the vertical distance
between the posterior teeth. The posterior open bite might
have been caused by the hypotonic tongue, which had
tooth imprints along its lateral border.18,19 Surgery of the
maxilla aggravated the posterior open bite (Fig 6), but
atrophy of the mandibular alveolar rim and the rigid
masticatory muscles were contraindications for the
procedure. Also, the syndrome elevated the surgical
risks, especially for necessary postoperative patient
care. Fortunately, facial and occlusal analyses
showed that surgical intervention in the maxilla with
complementary orthodontic treatment in the mandibular arch could produce a satisfactory result.4,5,20
Janson et al 295
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 136, Number 2
Fig 9. Posttreatment study models.
Fig 11. Posttreatment panoramic radiograph.
Fig 10. Posttreatment cephalometric tracing.
The impacted mandibular left second and third
molars should have been removed, but the surgical
difficulty experienced with the right third molar extraction and the reduced bone width eliminated the procedure. In addition, patients with Down syndrome could
have blood alterations that might cause complications
296 Janson et al
Table I.
Definitions of cephalometric variables
A-Nperp
P-Nperp
Convexity
SN.GoGn
Mx1.NA
Mx1-NA
Mx1-PP
Mx6-PP
Md1.NB
Md1-NB
Md1-GoMe
Md5-GoMe
IMPA
Overjet
Overbite
Nasolabial
angle
ST
convexity
Upper 1
exposure
Upper lip
to E
Lower lip
to E
Linear distance from A-point to perpendicular to
Frankfort plane through N
Linear distance from pogonion to perpendicular to
Frankfort plane through N
Angle between NA line and AP line
Angle between SN line and GoGn plane
Angle between maxillary central incisor long axis
and NA line
Perpendicular distance between the labial surface of
the maxillary central incisor and NA line
Perpendicular distance between the incisal edge of
the maxillary central incisor and the palatal plane
Perpendicular distance between the mesiobuccal
cusp of the maxillary first molar and the palatal
plane
Angle between the mandibular central incisor long
axis and NB line
Linear distance from the labial surface of the
mandibular central incisor to NB line
Perpendicular distance between the incisal edge of
the mandibular central incisor and the mandibular
plane
Perpendicular distance between the buccal cusp of
the mandibular second premolar and the
mandibular plane
Incisor-mandibular plane angle
Distance from the incisal edge of the mandibular
incisor to the incisal edge of the maxillary
incisor, measured parallel to the functional
occlusal plane
Distance from the incisal edge of the mandibular
incisor to the incisal edge of the maxillary
incisor, measured perpendicular to the functional
occlusal plane
Angle between columella, subnasale, and labrale
superius
Angle formed between soft-tissue glabella,
subnasale, and pogonion
Distance between the incisal edge of the maxillary
central incisor and the most inferior point on the
upper lip
Linear distance from upper lip to E line (line
between pronasale and soft-tissue pogonion)
Linear distance from lower lip to E line (line
between pronasale and soft-tissue pogonion)
such as infections or healing problems. These patients
have a reduced resistance to infections because of
deficiency of blood circulation in the terminal vascular
areas, defects of T-cell maturation, problems in the
polymorphonuclear leukocytes and neutrophil chemotaxis, and deficits in phagocytosis and intracellular
destruction.7-9
Because of the limited number of natural teeth in
the mandible and the small mandibular body height in
the molar area, the mandibular left deciduous canine
was extracted to mesialize the permanent canine, opening a space between it and the first premolar to receive
American Journal of Orthodontics and Dentofacial Orthopedics
August 2009
Table II.
Pretreatment and posttreatment cephalometric
status
Measurement
Maxillary components
SNA (°)
A-Nperp (mm)
Mandibular components
SNB (°)
P-NPerp (mm)
Maxillomandibular
relationship
ANB (°)
Convexity (NAP) (°)
Facial growth pattern
SN.GoGn (°)
Maxillary dentoalveolar
components
Mx1.NA (°)
Mx1-NA (mm)
Mx1-PP (mm)
Mx6-PP (mm)
Mandibular dentoalveolar
components
Md1.NB (°)
Md1-NB (mm)
Md1-GoMe (mm)
Md5-GoMe (mm)
IMPA (°)
Overjet (mm)
Overbite (mm)
Soft-tissue components
Nasolabial angle (°)
ST convexity (°)
Upper 1 exposure
(mm)
Upper lip to E (mm)
Lower lip to E (mm)
Norm29-35 Pretreatment Posttreatment
82
1
77.5
⫺3.5
80.6
⫺0.3
80
⫺2-4
82.2
6.8
83.5
11.0
2
3
⫺4.7
⫺14.7
⫺2.9
⫺12.5
32
27.7
25.2
22
4
30.3
25.5
33.9
6.4
24.8
22.6
35.1
8.3
26.1
24.5
25
4
44.5
—
90
2.08
2.87
6.5
⫺1.4
37.2
28.1
74.2
1.7
0.5
18.2
0.4
38.2
25.9
87.3
4.3
3.3
110
12
2
85.7
⫺9.9
2.9
75.6
⫺7.3
3.7
⫺6
⫺4
⫺8.9
⫺4.1
⫺6.8
⫺2.4
an implant (Figs 5-7).21,22 This increased the possibility
for favorable bone formation in an ideal and stable site
for future rehabilitation with an implant.23 Horizontal
and vertical increases of the alveolar bone always occur
with tooth movement.24-26 Also, the number of replacement teeth would be increased with the procedure.
After the LeFort I osteotomy and fixation with
titanium miniplates, the remaining posterior open bite
was closed with vertical intermaxillary elastics, leveling the occlusal plane by tooth extrusion.10,27,28 The
intermaxillary elastics were introduced immediately
after the surgical procedure and were used continuously
for 4 months until satisfactory and stable occlusal contacts
were obtained. During this procedure, a 0.019 ⫻ 0.025-in
stainless steel rectangular archwire in the maxillary
arch and an 0.018-in round wire in the mandibular arch
were used. The changes in the variable Mx6-PP confirm the maxillary molar extrusion. However, there was
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 136, Number 2
Fig 12. Superimposed cephalometric tracings.
mild reduction in the variable Md5-GoMe. It was
speculated that this resulted from distalization and
slight distal tipping of the premolars. The more the
posterior teeth move distally, the closer the teeth are to
the mandibular plane (Table II).
A partial removable prosthesis was placed after
treatment to rehabilitate the edentulous area (Fig 8).
This treatment option was chosen because of insufficient bone in the posterior area of the mandible, a
contraindication for implant placement.
CONCLUSIONS
This case report demonstrates that surgical options
can be satisfactory in patients with Down syndrome.
They can be excellent orthodontic patients. The orthodontic-surgical protocol provided good maxillary incisor exposure and excellent functional occlusion, and
improved the patient’s midface retrusion. Rehabilitation with a removable prosthesis showed that treatment
had realistic rather than idealistic objectives.
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