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Copyright © 2016 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
Midfacial Protraction With Skeletal Anchorage After
Pterygomaxillary Separation
Luciane Macedo de Menezes, DDS, MSc, PhD,
Roge
´rio Belle de Oliveira, DDS, MSc, PhD,
y
Andre
´Weissheimer, DDS, MSc, PhD,
z
and Rafael Linard Avelar, DDS, MSc, PhD
§
Abstract: The present article reports the treatment of a 7-year-old
girl with maxillary hypoplasia associated with multiple tooth
agenesis through maxillary protraction with skeletal anchorage
and pterygomaxillary separation. Two titanium mini-plates were
placed in the lateral region of the nasal cavity and used as anchorage
for maxillary protraction with a reverse-pull facemask. Pterygo-
maxillary separation was also performed to enhance the effects of
maxillary protraction. One week after surgery, 300 g of force was
applied on each side to protract the maxilla. Active treatment time
was 4 months, with 12 additional months of follow-up. Analysis of
the cone beam computed tomography images demonstrated that
skeletal anchorage enabled the correction of the maxillomandibular
discrepancy, with an improvement in facial appearance and occlu-
sion and with no dental effects. Pterygomaxillary separation was not
effective, showing no superior orthopedic response on maxillary
advancement or restrictions to maxillary growth in the 12-month
post-treatment follow-up.
Key Words: Bone-anchored miniplates, class III malocclusion-
growing patient, mandibular prognathism, maxillary hypoplasia,
maxillary protraction
(J Craniofac Surg 2016;27: 1561–1564)
Class III skeletal malocclusion is characterized by an antero-
posterior deficiency of the maxilla and/or mandibular prog-
nathism, resulting in anterior crossbite and a concave facial profile.
Patients with maxillary retrognathia may be treated during growth
via maxillary protraction with a facemask and intraoral ancho-
rage.
1–3
However, when the maxillary deficiency is associated with
multiple tooth agenesis, there is insufficient support or anchorage
for conventional maxillary protraction. In such patients, skeletal
anchorage with the use of titanium mini-plates allows for ortho-
pedic forces to be applied directly on the maxilla, thereby
potentiating the skeletal effects and avoiding undesirable effects
on the teeth.
4
This paper reports the treatment of a 7-year-old girl with a facial
deformity characterized by maxillary hypoplasia associated with
multiple tooth agenesis. The treatment consisted of maxillary
protraction and skeletal anchorage combined with separation of
the pterygoid processes of the maxilla.
CLINICAL REPORT
The patient KBG, a 7-year-old girl, exhibited a concave facial
profile, retruded upper lip and lack of projection of the zygomatic
region, indicating an anteroposterior deficiency of the maxilla. The
mandible was normal in size, as evidenced by the adequate length of
the chin-neck line. There was no evident asymmetry and the lower
third of the face was slightly diminished. Angle Class III malocclu-
sion was observed, with anterior and posterior crossbite as well as
multiple tooth agenesis (Fig. 1). The cephalometric analysis
revealed a Class III skeletal pattern (ANB 4.38, Wits
8.2 mm) due to the maxillary deficiency (SNA 76.48, A-NPerp
2.7 mm), with a horizontal facial growth pattern (GoGn.Sn 31.48,
FMA 20.98, Y-axis 538), and diminished lower facial third (ANS-
Me 48.6 mm). The upper incisors were proclined (1.NA 27.58) and
the lower incisors were retroclined (1.NB 19.98). The soft tissue
analysis revealed retrognathia of the upper lip in relation to the E
plane (Table 1).
The treatment objectives were to reduce the facial concavity via
an orthopedic response of the maxilla with minimal dentoalveolar
movement to ultimately improve the facial appearance and occlu-
sion and induce subsequent normal maxillary growth.
Three treatment alternatives were established: wait until growth
was completed to perform orthognathic surgery; maxillary protrac-
tion associated with conventional intraoral anchorage; and maxil-
lary protraction using skeletal anchorage with mini-plates.
Two orthodontic mini-plates (NeoOrtho, Curitiba, Parana´, Bra-
zil) were placed in the canine pillar region through an intraoral
incision from the deciduous canine to the contralateral deciduous
canine. Surgery was performed with the patient under general
anesthesia. The mini-plates were placed near the nasal aperture
with 2 self-drilling titanium screws (2.0 mm in diameter and 5 mm
in length) (Fig. 2A). Pterygomaxillary separation was performed
with a chisel and hammer to separate the medial and lateral
pterygoid laminas from the maxilla. One week after surgery,
maxillary protraction was initiated with the use of a Petit facemask,
with 300 g of force per side that was 308downward to the occlusal
plane (Fig. 2B and C). The patient was instructed to use the
facemask as much as possible and to replace the elastics daily.
In the 4th month of treatment, the mini-plate on the left side
exhibited excessive mobility, causing discomfort to the patient;
it was therefore removed prematurely, interrupting the treatment.
The Digital Imaging and Communications in Medicine files
containing cone beam computed tomography images of the differ-
ent phases of treatment were imported to the Dolphin Imaging 11
software (Dolphin Imaging, Chatsworth, CA) and synthetic images
From the Department of Orthodontics; yDepartment of Oral and
Maxillofacial Surgery; zOrthodontic Program, Pontificial Catholic
University of Rio Grande do Sul (PUCRS), Partenon; and §Department
of Oral and Maxillofacial Surgery, Center University Unichristus,
Fortaleza, Brazil.
Received August 31, 2015.
Accepted for publication March 27, 2016.
Address correspondence and reprint requests to Rafael Linard Avelar,
DDS, MSc, PhD, Faculdade de Odontologia, Pontificial Catholic
University of Rio Grande do Sul (PUCRS), Pre´dio 6, Av Ipiranga, 6681,
sala 209, Partenon, Porto Alegre/RS, CEP: 90619-900, Brazil;
E-mail: rafael.linard@hotmail.com
The authors report no conflicts of interest.
Copyright #2016 by Mutaz B. Habal, MD
ISSN: 1049-2275
DOI: 10.1097/SCS.0000000000002840
TECHNICAL STRATEGY
The Journal of Craniofacial Surgery Volume 27, Number 6, September 2016 1561
Copyright © 2016 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
similar to conventional radiographs were generated to permit
conventional cephalometric analysis and superimposition. The
3D reconstructions and 3D superimpositions were generated from
the same Digital Imaging and Communications in Medicine files,
but the Invivo Dental 5.0 software (Anatomage Inc, San Jose, CA)
was used.
The results demonstrated an improvement in the maxilloman-
dibular relation, an establishment of normal vertical facial dimen-
sion, and a reduction in the facial concavity, which became mildly
convex (Table 1, Figs. 3 and 4). Figure 3B and E shows the results
after 1 month of maxillary protraction, which demonstrated an
improvement in the maxillomandibular relationship (3.38of
increase in ANB and 4.4 mm in Wits). There was almost no anterior
displacement of the maxilla (SNA 76.68and A-NPerp 2.7 mm),
and there was a mild counter-clockwise rotation of the palatal plane
that induced a mandibular downward and backward rotation (3.18of
reduction in SNB and 5.5 mm of reduction in Pog-NPerp), thereby
improving facial appearance. There was an increase in the man-
dibular plane (increase in Sn.GoGn by 28, FMA by 2.18), with a 4.7-
mm increase in the lower anterior facial height (ANS-Me). There
were no changes in the upper and lower incisors axial inclinations.
The upper lip advanced 1.7 mm, and the lower lip was retracted
in 1.6 mm.
The 12-month follow-up revealed an improvement in maxillary
position (SNA 78.48) and maxillomandibular relation (ANB 1.48
and Wits 4.5 mm) as well as a positive overjet and maintenance of
a pleasing, esthetic facial (Figs. 3 and 4). Maxillary growth was
normal throughout this period, as evidenced by the increases in the
maxillary and mandibular anteroposterior lengths (Table 1).
FIGURE 1. Pretreatment records. (A – C) Facial photographs. (D –F) Intraoral
photographs. (G, H) Synthetic radiographs generated from cone beam
computed tomography.
TABLE 1. Cephalometric Measurements
Variables Normal Initial
1 Month
Treatment
12 Months
Post-Treatment
Maxillary
SNA (8) 82 76.4 76.6 78.4
A-NPerp (mm) 0 2.8 2.7 0
Maxillary length
(Co-A) (mm)
85 77 77.6 81
Mandibular
SNB (8) 80.9 80.7 77.6 79.8
Pog-NPerp (mm) 4.0 4.5 1.0 5.2
Mandibular length
(Co-Gn) (mm)
110.4 102.4 101.4 105.3
Maxillomandibular
ANB (8) 1.6 4.3 11.4
Wits appraisal (mm) 18.2 3.8 4.5
Vertical
Sn.GoGn (8) 33 31.4 33.4 31.4
FMA (8) 25.8 20.9 23 20.1
Y-axis (8) 60.9 53 56.4 52.6
Anterior facial Ht
(ANS-Me) (mm)
62.6 47.9 52.6 51.3
Dental
U1-NA (8) 22.8 27.5 30.5 31
U1-NA (mm) 4.3 4.1 5 5.5
L1-NB (8) 25.3 19.9 17.6 18.5
L1-NB (mm) 4 1.2 1 1.6
IMPA (8) 95 87.8 86.6 87.3
Soft-tissue
Upper lip to E-plane (mm) 2.1 3.9 2.2 3.1
Lower lip to E-plane (mm) 2.0 1.4 3.0 1.5
FIGURE 2. (A) Mini-plates placed to the lateral walls of the nasal cavity. (B, C)
Maxillary protraction with skeletal anchorage and facemask.
FIGURE 3. (A –C) 3D reconstructions from cone beam computed tomography
with the InVivo Dental software. (A) Pretreatment. (B) One month of treatment.
(C) Twelve months post-treatment. (D) Conventional cephalometric
superimposition. (E, F) 3D superimposition. (E) Pretreatment (gray) and 1
month of treatment (blue). (F) Pretreatment (gray) and 12 months post-
treatment (blue).
de Menezes et al The Journal of Craniofacial Surgery Volume 27, Number 6, September 2016
1562 #2016 Mutaz B. Habal, MD
Copyright © 2016 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
DISCUSSION
Different approaches have been used to correct maxillary retrusion
in growing patients. The usual treatment consists of rapid maxillary
expansion (RME) followed by maxillary protraction with face-
mask.
5
Other methods use skeletal anchorage with mini-screws or
mini-plates placed in the maxilla and a facemask.
6–8
Another option
to achieve maxillary protraction is the use of intermaxillary traction
with elastics between the mini-plates placed in the maxilla and the
mandible.
9
Distraction osteogenesis may be used in patients with
severe maxillary hypoplasia.
10
Multiple tooth agenesis dictated the
treatment choice for this patient for the use of mini-plates and
facemask therapy. Protraction of the maxilla with mini-plates
alone
9
was not considered because this technique had not yet been
published. Distraction osteogenesis was not considered because the
midfacial deficiency was not severe.
Rapid maxillary expansion has been used to disarticulate the
circummaxillary sutures, enhancing the orthopedic effects of the
maxillary protraction.
5
However, a meta-analysis and a randomized
clinical trial demonstrated no differences in the amount of maxillary
protraction with or without RME.
2,3
Therefore, in the absence of
transverse maxillary discrepancy, RME would not enhance maxil-
lary protraction.
3
In the present patient, RME was not performed
because the posterior crossbite resulted from a distal sagittal
position of the maxilla in relation to the mandible and was not
due to a real transverse maxillary deficiency. The posterior cross-
bite was corrected with maxillary protraction alone, which induced
downward and backward mandibular rotation, thereby improving
the maxillomandibular transversal relationship.
Skeletal anchorage associated with maxillary protraction
requires special considerations regarding the position and stability
of the mini-plates. The recommended sites for mini-plates place-
ments in the maxilla are the infrazygomatic crests
6,9
and the lateral
walls of the nasal cavity adjacent to the piriform aperture.
8
The
infrazygomatic crest has the advantage of being far from the
developing permanent teeth and presents good bone quality, which
is essential to anchorage and screws stability. The lateral wall of the
nasal cavity has the advantage of being located anteriorly to the
center of resistance of the nasomaxillary complex, allowing pro-
traction forces in harmony with the normal facial growth. More-
over, this site seems to be the most appropriate location to achieve
fullness of the naso-buccal folds, the infraorbital region, and,
consequently, the soft-tissue profile.
8
However, no studies were
found in the literature that assessed and compared the lateral region
of the nasal cavity and infrazygomatic crest in terms of bone
quantity and density to determine which region provides greater
stability when using skeletal anchorage. Regarding the number of
screws, some authors recommend 3 or 4,
6
whereas others have
achieved good stability with only 2 or 3 screws.
8
The latency time
for the application of forces on mini-plates should be minimal
because an immediate load with adequate forces increases the bone
density around the screws. Therefore, the recommendation for
initiating maxillary protraction ranges from 1
6,8
to 3 weeks.
9
The
suggested force ranges from 100 g per side, increasing to 200 g in
the following month,
9
until 300 g of initial force is attained.
6
In the
present patient, the mini-plates were placed in the lateral walls of
the nasal cavity with 2 screws each, and 300 g of force was applied
after 1 week. The mini-plate on the left side presented excessive
mobility in the 4th month of treatment and was removed. The
anatomic limitation of this patient, which did not allow the use of
mini-plates with more than 2 screws, and the fact that the screws
were submitted to forces that were expulsive, may have contributed
to the loss of stability of the mini-plate. Better results may have
been obtained if the mini-plates had been placed in the infrazygo-
matic region with 3 or 4 screws.
The literature demonstrates that small anterior movement of the
maxilla (an increase in SNA of 1.78and ANB of 2.88) may be
obtained with conventional maxillary protraction.
(kim)
With the use
of skeletal anchorage, the orthopedic effects of maxillary protrac-
tion can be even greater.
6–8
The use of skeletal anchorage and
facemask therapy for 20 months of treatment has been reported to
produce maxillary advancement (point A) of 8.1 mm and an
increase in the ANB angle of 8.98, with no dental effects.
6
Another
study involving skeletal anchorage reported point A advancement
of 4.8 mm (ranging from 2.8 to 8.6 mm), an increase in SNA of 3.78,
ANB of 6.18and Wits of 9.0 mm, with a mean treatment time of
10.8 months (2008).
The results of the present study revealed that the separation of the
pterygoid processes, which was performed to reduce maxillary
posterior resistance, was not effective. No superior orthopedic
response of maxillary protraction was observed, considering the 4
months of treatment, when compared with previous studies with no
pterygoidseparation.
4,6,7
The hypot hesis that possible s urgical trauma
during the pterygoid processes of the maxilla separation could cause
restriction of maxillary growth was not confirmed. The 12-month
follow-up demonstrated normal maxillary growth (Table 1). How-
ever, randomized, prospective clinical trials that assess the effects of
pterygomaxillary separation as a coadjuvant to maxillary protraction
are needed so that conclusions based on quality evidence can be
established. The treatment objectives, which included crossbite cor-
rection, reduction in the concavity of the profile, and significant
improvement in facial appearance, were achieved.
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FIGURE 4. Records 12 months post-treatment. (A– C) Facial photographs.
(D– F) Intraoral photographs. (G, H) Synthetic radiographs generated from cone
beam computed tomography.
The Journal of Craniofacial Surgery Volume 27, Number 6, September 2016 Pterygoid Separation and Midfacial Protraction
#2016 Mutaz B. Habal, MD 1563
Copyright © 2016 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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de Menezes et al The Journal of Craniofacial Surgery Volume 27, Number 6, September 2016
1564 #2016 Mutaz B. Habal, MD
