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Title: Osteogenic uni- or bilateral form of the guided rapid maxillary expansion
Author: K. Al-Ouf; C. Krenkel; M.Y. Hajeer; S. Sakka
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Journal of Cranio-Maxillo-Facial Surgery (2010) 38, 160e165
Ó 2009 European Association for Cranio-Maxillo-Facial Surgery
doi:10.1016/j.jcms.2009.03.011, available online at http://www.sciencedirect.com
Osteogenic uni- or bilateral form of the guided rapid maxillary expansion
K. AL-OUF, Head of the Oral and Maxillofacial Surgery Unit1, C. KRENKEL, Professor and Head of Oral and
Maxillofacial Surgery Department2, M. Y. HAJEER, Senior Lecturer in Orthodontics3, S. SAKKA, Senior Lecturer in
Oral and Maxillofacial Surgery3
Central Police Hospital, Damascus, Syria; 2 Paracelsus University, Muellner Hauptstr 48, 5020 Salzburg, Austria;
University of Albaath Dental School, Hamah, Syria
SUMMARY. Surgically assisted rapid palatal expansion is an important treatment procedure in patients with constricted maxillae. Several surgical methods have been proposed to expand the maxilla bilaterally. A new technique was developed for performing a symmetric or asymmetric maxillary expansion guided by the stability
of the mid-palatal area employing two osteotomy cuts on either side of mid-palatal suture. A Hyrax-type expansion device was used post-operatively. Seventeen patients were included in the study (9 males, 8 females) with
a mean age of 30.7 years. Inter-canine and inter-molar widths were evaluated at three assessment intervals: before treatment (T1), immediately after appliance removal (T2) and at six months follow-up (T3). Between T1 and
T2, a mean expansion of 7.1 and 9.9 mm was achieved at the canine and molar areas, respectively. The amount of
relapse measured between T2 and T3 was minimal (a mean value of 0.35 and 0.8 mm at the canine and molar
areas, respectively). Asymmetric expansion was performed in 6 patients who exhibited unilateral skeletal constriction at the initial assessment and these cases appeared stable at T3. The surgical approach described in
the current study enabled rapid maxillary expansion of unilateral and bilateral skeletal constriction cases effectively and with good stability. Ó 2009 European Association for Cranio-Maxillo-Facial Surgery
Keywords: rapid maxillary expansion, palatal osteogenesis, asymmetric expansion
Steinhauser described a surgical technique in which an
osteotomy similar to a Le Fort I osteotomy was performed for immediate maxillary widening. Bony segments were moved apart and the resultant space was
filled by transplanted autologous bone (Steinhauser,
When reviewing the literature, several methods have
been proposed to perform osteotomies on the maxillary
complex for maxillary expansion. One of these methods
included an osteotomy extending from the piriform aperture to the maxillary tuberosity. Expansion could be then
executed by ordinary skeletal screws (Timms and Vero,
1981). Another method was dependent on an osteotomy
in the zygomatic process in conjunction with an osteotomy in the palatal area (Kaban, 1984), whereas Zoeller
and Ullrich performed an osteotomy in zygomatico-maxillary process area in addition to the mid-palatal suture
(Zoeller and Ullrich, 1991).
Glassman et al. performed an osteotomy in the faciomaxillary wall starting from the naso-frontal suture and
ending at the maxillary tuberosity (Glassman et al.,
1984). When Schimming et al. applied this method on
their patients, a case with a fracture in the alveolar ridge
of the maxillary bone was recorded due to the ossification of the mid-palatal suture (Schimming et al., 2000).
Bell and Epker performed a surgical cut similar to Le
Fort I osteotomy, in which all the facial bony structures
were cut in addition to the osteotomy that was performed
in the mid-palatal suture area (Bell and Epker, 1976).
Then expansion was accomplished gradually and bone
Expansion of the upper jaw cannot be performed by the
use of traditional orthodontic appliances (e.g. Haas or
Hyrax appliances) when the mid-palatal suture becomes
totally ossified (Moss, 1986). Therefore, osteotomies
are indicated to facilitate expansion movements and to
avoid overloading the teeth which may be accompanied
by bone resorption (Moss, 1968).
Hippocrates was the first to write about the constricted
upper jaw (Lindorf, 2006). From 1730, several appliances were utilized to expand the maxilla. In 1860, Dr
Angell accomplished a conservative and non-surgical
maxillary expansion procedure (Angell, 1860). Derichsweiler described the same procedure in 1950 (Derichsweiler, 1953, 1958). ‘Rapid’ maxillary expansion was
first used and popularized by Haas who employed this
technique in the treatment of patients with constricted
maxillary jaws (Haas, 1961, 1980).
For a long time, it has been thought that the median palatal suture is the area most resistant to maxillary expansion (Morselli, 1997). It has been shown that other
sutures might play a similar role to the median palatal suture (Isaacson and Murphy, 1964; Isaacson et al., 1969).
Several studies demonstrated that the fronto-maxillary,
zygomatico-maxillary and pterygo-maxillary sutures
were resistant areas for maxillary expansion procedures
(Lines, 1975; Bell and Jacobs, 1979). One study stressed
that the maximum resistance to maxillary expansion came
from the zygomatic arch (Wertz and Dreskin, 1977).
Author's Personal Copy
Osteogenic uni- or bilateral form of the guided rapid maxillary expansion 161
deposited in a way similar to the osteogenesis procedures
described by Ilizarov in medicine (the treatment of bone
lengthening of ends) (Ilizarov, 1990; McCarthy et al.,
Moreselli used a minor surgical procedure to perform
maxillary expansion and thought that the mid-palatal suture did not play a primary role when expanding the maxilla (Morselli, 1997). When Mommaerts et al. applied
a similar approach using endoscopically assisted corticotomies to perform transpalatal osteodistraction, they
found that the operative time as well as both percentage
and nature of complications were similar to those experienced with ‘open-sky transpalatal distraction’ with less
pronounced oedema (Mommaerts et al., 2008).
Stroemberg and Holm, after a longitudinal follow-up
of patients with maxillary expansion, found that the inter-molar width was increased by a mean amount of
7.1 mm, whereas the inter-canine width was increased
a mean amount of 4.8 mm. They found that the mid-palatal suture might remain unossified for a long time
(Stromberg and Holm, 1995).
Lindorf applied selective weakening procedures to the
facial bones and used mini-plates to create what could be
called ‘semi-stabilization’. In addition, he employed inter-maxillary elastics to guide the expansion procedure
It has been noted from the literature review that several
surgical approaches to maxillary expansion as well as
several opinions about the most suitable lines of osteotomies have been proposed. The aim of the current paper is
to describe and evaluate a modification of the conventional method of surgically assisted rapid maxillary expansion by the application of two osteotomies on either
side of the mid-palatal suture which is followed by ordinary maxillary widening and bone formation. This technique is referred to as ‘‘Osteogenic Uni- or Bilateral
Form of Rapid Maxillary Expansion’’ (OUF-RME).
MATERIALS AND METHODS
Seventeen patients (8 females and 9 males) with skeletal
transverse discrepancies in the maxilla were treated between 2005 and 2008 at the Department of Oral and
Maxillofacial Surgery at Paracelsus Medical University,
Salzburg (Austria) as well as at the Department of Oral
and Maxillofacial Surgery at Police Hospital in Damascus (Syria). The average patient age was 30.7 years.
Mandibular prognathism was diagnosed in 13 patients
whereas maxillary retrognathism occurred in 12 patients,
with 8 patients being diagnosed as having both skeletal
abnormalities. All patients exhibited skeletal posterior
crossbite either uni- or bilaterally. Orthodontic brackets
were placed on the anterior teeth in 14 cases pre-operatively, whereas 3 cases just underwent orthodontic treatment post-operatively.
Ligation options between the upper six teeth depended
on the treatment plan. A Hyrax-type expansion appliance
was used with four bands on the upper first premolars
and upper first molars.
Fig. 1 e Frontal view showing the lines of osteotomies on the maxillary
Fig. 2 e Occlusal view of the maxillary complex showing the bilateral
osteotomies extending from the midpoint between the upper lateral and
the canine (on the right side) and between the upper central and lateral
incisor (on the left side). These osteotomies are extended to the posterior
border of the maxillary complex.
OUF-RME surgical technique
The procedure was performed under general anaesthesia
and local infiltration with a vasoconstrictor (Adrenaline,
1:100,000 concentration) which was applied on both sides
of the oral vestibule. Oral intubation was used for general
anaesthesia since the surgical osteotomies were performed through the nasal cavity floor and not from the palatal area. The palatal mucosa was kept intact throughout
the procedure. An incision was made in the mucosal membrane and the periosteum in the depth of the vestibule.
This incision extended from the first molar on the right
side to the first molar on the other side. Soft tissues
were dissected at the canine fossa as well as the maxillary
tuberosity. Dissection was also made along the floor of the
nasal cavity towards the soft palate. Intra-operatively, the
patient was given intravenous antibiotics.
Author's Personal Copy
162 Journal of Cranio-Maxillo-Facial Surgery
Fig. 3 e Lateral views. A e right view, B e left view. The lateral osteotomy line extends from the lower margin of the pirifrom aperture of the nasal
cavity towards the posterior margin of the maxillary complex.
Fig. 4 e This intra-oral photograph shows the OUF-RME lines of
osteotomies in the anterior region of the maxilla. It can be seen that two
vertical osteotomies extend from the horizontal osteotomies towards the
interdental alveoli between the central and lateral incisors bilaterally.
The anterior nasal spine area was not cut during the
procedure; therefore, there was no possibility of injuring
the naso-palatal nerve or artery. This was followed by
a separation of the main facial pillar zones e the frontal
process area and the zygomatic process area of the maxillary bone using a surgical saw, and the pterygo-maxillary process area by a Kawamoto chisel (Figs. 1e3a
and 4b). Osteotomy was performed on both sides of
the mid-palatal suture in the floor of the nasal cavity
starting from the posterior border and continuing towards
the anterior border of the piriform aperture. The osteotomy extended between teeth 11 and 12 or 12 and 13
on the right hand side, and between teeth 21 and 22 or
22 and 23 on the left hand side (Fig. 4). A long saw blade
was used for this procedure and injury to the palatal mucosa was avoided.
A fine chisel was used to separate the alveolar ridge
bone between the anterior teeth. A bony separator device
was used to completely mobilise the bone on both sides
of the osteotomy line (Fig. 5). In this manner, the midpalatal area remained stable because of its attachment
to the vomer as well as the mid-nasal areas. This stable
mid-palatal area played a major role in guiding the subsequent maxillary expansion.
Great care was taken to ensure that the bilateral maxillary segments were properly mobilised on both sides in
order to facilitate the expansion movements. Finally,
flaps were replaced and sutured. Following the surgical
Fig. 5 e A bony separator device is used to mobilise the bone
completely and thoroughly.
intervention, the Hyrax-type appliance was cemented
onto the upper first premolars and molars (14, 24, 16
and 26). The screw was turned four times (each turn is
equivalent of 0.25 mm) with an initial expansion of
1 mm intra-operatively. To avoid post-surgical oedema
the patients were asked not to blow their nose and to
breathe gently (Tuinzing et al., 2005).
The protocol of the following activations of the skeletal expansion device was similar to the other rapid maxillary expansion techniques after a latency period of one
week. The expansion procedure was continued until
good transverse posterior relationships were achieved.
The Hyrax-type device was maintained for an additional
three months for retention. Orthodontic treatment was
continued until the patients achieved their final planned
Alginate impressions were taken at the beginning of
treatment (T1), immediately after appliance removal
(T2) and six months following appliance removal (T3).
Study model analysis included the measurement of inter-canine and inter-molar widths at the three assessment
intervals using digital calipers (Fig. 6).
This technique showed good results in expanding the
maxilla, which was guided through the stable positioning
Author's Personal Copy
Osteogenic uni- or bilateral form of the guided rapid maxillary expansion 163
of the mid-palatal area (Table 1). When measuring the inter-canine width, a mean expansion of 7.1 mm was
achieved, whereas the expansion at the molar area
reached a mean value of 9.9 mm. After an average follow-up of six months, there was a mean decrease of
0.35 mm in the inter-canine width, whereas the relapse
at the molar area reached a mean value of 0.8 mm. In
general, the current study showed that a mean net expansion of 6.7 mm and 9.1 mm can be achieved at the canine
and molar areas, respectively, when the OUF-RME was
employed. It should be noted that asymmetric expansion
was carried out in 6 patients who exhibited unilateral
skeletal constriction at the initial assessment. The stability of the mid-palatal area aided in stabilising upper teeth
on their relative positions on arch circumference and
moving the required teeth (which are in a posterior crossbite) laterally. In this way, we were able to treat unilateral
skeletal constriction cases as well as bilateral constriction
cases effectively and accurately.
Figs. 7e10 present a skeletal Class III malocclusion in
a patient aged 22 years who was treated by the OUFRME technique. At the beginning of treatment, the
patient presented with a bilateral crossbite related to maxillary skeletal constriction (Fig. 7). A Hyrax-type RME
appliance was tried-in (Fig. 8) and brackets were applied
on the upper anterior teeth (Fig. 9). Following the completion of RME, the patient presented a satisfactory maxillary width (Fig. 10). The patient underwent retention for
three months and a comprehensive fixed appliance treatment was commenced afterwards.
The speed of maxillary expansion using this method
appeared greater than that of other rapid maxillary techniques dependant on a single osteotomy along the midpalatal suture. The average expansion time was 17
days. No complications were observed such as haemorrhage, infection, hyper-mobility and asymmetry with
the exception of post-surgical swelling which was common with such surgical interventions.
By using this technique, osteogenesis occurs at the sites
of distraction of the bony segments of the maxilla. Expansion can be guided through the stable position of
the mid-palatal suture area. This design of osteotomies
enables the orthodontist to choose any of the two sides
Fig. 6 e Measurements performed on study models. IC: Intercanine,
Table 1 e Sample characteristics, inter-canine and inter-molar widths at assessment intervals
Inter-canine width (mm) at
Inter-molar width (mm) at
T1: Before treatment, T2: immediately after appliance removal, T3: at six-month follow-up.
* Asymmetric expansion was performed through the stable mid-palatal area.
Author's Personal Copy
164 Journal of Cranio-Maxillo-Facial Surgery
Fig. 7 e Pre-surgical intra-oral photograph showing the initial
malocclusion which was characterised by a Class III skeletal
relationship as well as skeletal maxillary constriction.
Fig. 9 e Brackets were placed on the upper anterior teeth (from canine
to canine). This was done to enable the surgeon to perform a unilateral
expansion when needed.
Fig. 10 e Post-expansion intra-oral photograph showing the final result
with satisfactory upper inter-molar and inter-premolar widths.
Fig. 8 e Pre-surgical intra-oral photograph showing an occlusal view of
the Hyrax-type RME device when it was tried-in. No cementation was
done at this stage.
of the maxillary segments to be ligated to the central part
of the maxillary bone (which carries two to four incisors). Therefore, expansion can be directed towards the
right or left side of the patient’s maxilla (i.e. unilateral
expansion), an approach which has not been well evaluated in the literature (Stromberg and Holm, 1995;
Morselli, 1997; Schimming et al., 2000).
In the current study, the mean expansion achieved at
the canine and molar areas exceeded that documented
in other studies (Stromberg and Holm, 1995; Morselli,
1997; Schimming et al., 2000). The procedure appeared
stable when measured in the anterior and posterior segments of the maxilla and the mean value of relapse
seemed to be less than that reported in earlier studies
(Stromberg and Holm, 1995; Schimming et al., 2000).
Despite performing double osteotomies, good stability
can be attributed to the presence of the mid-palatal area
which enhanced the post-expansion stability of the
moved segments, in addition to the preservation of
the naso-palatal neurovascular bundle which improved
the blood supply to the bony segments and enhanced osteogenesis at the areas of distraction.
It should be noted that the measurements performed in
the current study were based on study models which re-
flected the positions of the crowns before and after the
surgically assisted expansion. However, good stability
of the posterior teeth in the long-term is dependent on
achieving proper axial inclination at the end of treatment
which was not evaluated in the current study. This limitation could have been overcome by evaluating frontal
cephalograms at the three assessment intervals (Doruk
et al., 2004).
OUF-RME may facilitate any further orthognathic
procedures, restrict the surgical intervention to the upper
jaw only, or it may eliminate the need for surgical correction. During the joint treatment planning, the surgeon
should discuss with the orthodontist the possibility of
conducting such procedure. The nasal cavity size and nasal breathing improve with this technique. Regarding external nasal changes, OUF-RME does not affect nasal
aesthetics. The philtrum does not change and no increase
in the width of the columella is found. This is because
para-saggital expansion does not cause stretching of
soft tissues that comprise the philtrum area. This aspect
need to be addressed and evaluated objectively in future
studies when the OUF-RME is used.
This technique is very useful for performing rapid palatal expansion in all skeletally narrow maxillae with the
exception of those cases with severely convergent roots
between the central and lateral incisors or between the
laterals and canines. In such cases, the operator should
seek other techniques or may be obliged to ask the
Author's Personal Copy
Osteogenic uni- or bilateral form of the guided rapid maxillary expansion 165
orthodontist to perform some pre-surgical space creation
for interdental osteotomies.
The OUF-RME has been shown to be effective in performing uni- or bilateral rapid maxillary expansion in patients with constricted maxillary bases. The achieved
expansion has been shown to be stable during follow-up.
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Dr K. AL-OUF
P.O. Box 25821
Tel.: +963 115419706
Fax: +963 112221843
Paper received 9 November 2008
Accepted 28 March 2009