Download Skeletal and Dental Changes After Rapid Maxillary Expansion (RME

ARAŞTIRMA (Research)
Hacettepe Diş Hekimliği Fakültesi Dergisi
Cilt: 33, Sayı: 1, Sayfa: 52-61, 2009
Skeletal and Dental Changes After Rapid
Maxillary Expansion (Rme) in Adolescents
and Surgically-assisted Rme (Sarme) In
Adults:
Two Years After Expansion
Adölesanlarda Hızlı Maksiller Genişletme (Hmg)
ve Erişkinlerde Cerrahi Destekli Hızlı Maksiller
Genişletme (Cdhmg) Sonrası İskeletsel ve
Dental Değişiklikler: Genişletme Sonrası 2 Yıllık
Takip
*İlken KOCADERELİ DDS, PhD, *Türkan Nadire GÜVENÇ DDS, **V. Selçuk ÇINAR DDS, PhD,
***C. Bahadır GİRAY DDS, PhD
*Hacettepe University Faculty of Dentistry Department of Orthodontics
**Private Practice
***Hacettepe University Faculty of Dentistry Department of Oral and Maxillofacial Surgery
ABSTRACT
ÖZET
Aim: To evaluate and compare posteroanterior skeletal and dental changes after rapid maxillary expansion (RME) in adolescents and surgically-assisted RME
(SARME) in adults and two years after expansion.
Subjects and method: The sample consisted of 20
patients. RME group consisted of 10 patients (6
female, 4 male) with a mean age of 13.03 ± 0.62
years. The SARME group consisted of 10 patients
(7 female, 3 male) with a mean age of 21.32 ± 1.21
years. Hyrax-type expanders were activated 0.25
mm/day. Posteroanterior cephalograms were obtained before expansion (T0), after expansion (T1) and
at two years after expansion (T2).
Amaç: Adölesanlarda Hızlı Maksiller Genişletme
(HMG) ve Erişkinlerde Cerrahi Destekli Hızlı Maksiller
Genişletme (CDHMG) ve genişletmeden 2 yıl sonrası posteroanterior iskeletsel ve dental değişiklikleri
değerlendirip karşılaştırmak amaçlanmaktadır.
Results: There was statistically significant increase in
nasal cavity width and jugular width at T0-T1 periods
for both groups. (p<0.05) The increase in nasal cavity
width in the adolescent group was preserved in the
following two years.
Bulgular: Her iki grup için T0-T1 aralığında nazal kavite ve juguler genişlikte anlamlı artış mevcuttur.(p<0,05)
Adölesan grubun nazal kavitesindeki artış takip eden
2 yılda korunmuştur.
Conclusion: No vertical dental changes occurred
after RME and SARME treatments and the following
Bireyler ve Yöntem: Örneklem 20 hastadan oluşmaktadır. HMG grubunu ortalama yaşı 13,03±0,62
yıl olan 10 hasta (6 bayan,4 erkek), CDHMG grubunu
ortalama yaşı 21,32±1,21 olan 10 hasta (7 bayan,3
erkek) oluşturmuştur. Hyrax tipi genişletme apareyleri
günde 0,25 mm aktive edilmiştir. Posteroanterior
sefalogramlar genişletme öncesi (T0), genişletme sonrası (T1) ve genişletmeden 2 yıl sonra (T2) alınmıştır.
Sonuçlar: HMG ve CDHMG tedavileri sonrası ve
takip eden 2 yılda vertikal dental değişiklik bulunmamıştır. Adölesan grupta HMG sonrası ve takip
53
two years period. More nasal cavity width increase
was found in the adolescents after RME and the
following two years. RME and SARME did not effect
the buccal vertical or palatinal vertical positions of the
maxillary first molar which was maintained during the
two follow-up-year period.
eden 2 yılda daha fazla nazal kavite değişikliği elde
edilmiştir. Ayrıca HMG ve CDHMG’nin, 2 yıllık takip
periyodunda da korunan maksiller I. moların bukkal
vertikal ve palatinal vertikal boyutunu etkilemediği
bulunmuştur.
KEYWORDS
RME, posteroanterior evaluation
ANAHTAR KELİMELER
HMG, posteroanterior değerlendirme
INTRODUCTION
Rapid maxillary expansion (RME) was proposed for maxillary transverse problems in the
19th century by Angell1. The rationale is that
the orthopedic force exerted by the expander
can open the midmaxillary suture which is usually patent in children, and thus the maxilla is
expanded2-7RME can produce unwanted effects
when used in a skeletally mature patient; including lateral tipping of posterior teeth4,5, extrusion8,
periodontal membrane compression, buccal root
resorption9,10, alveolar bone bending5, fenestration of the buccal cortex10, palatal tissue necrosis11, inability to open the midpalatal suture, pain
and instability of the expansion5,8 . Correction
of maxillary transverse deficiency in a skeletally
mature patient is more challenging because of
changes in the osseos articulations of the maxilla
with the adjoining bones12. So, surgically assisted
RME(SARME) has been proposed to produce
better treatment results in adults and to prevent
complications by surgically releasing the closed
sutures resisting the expansion forces4As the
number of adult seeking orthodontic treatment
has increased significantly, SARME has become
a popular treatment modality.
At the present few reports are available comparing RME and SARME13,14,15. Berger et al13,14
compared the two treatment modalities, but in
their first study, the two groups had different
age ranges because of skeletal maturity and only
photographic evaluation was performed in their
second study. Atac et al15 evaluated only preexpansion and postexpansion posteroanterior
cephalograms and no long term evaluation after
expansion.
The purpose of this study was to compare
posteroanterior skeletal and dental changes during the active phase of treatment for RME and
surgically assisted RME (SARME) and two years
after expansion.
Subjects and Methods
Subjects
The RME group consisted of 10 adolescent
patients (6 female, 4 male) with a mean age of
13.03± 0.62 years. The SARME group consisted
of 10 adult patients (7 female, 3 male) with a
mean age of 21.32±1.21 years.
The criteria for the selection of patients were
the presence of a unilateral or bilateral posterior
cross bite, having no craniofacial deformity or
tooth agenesis. In both groups occlusal radiographs were taken to evaluate midpalatal suture
opening. All subjects were informed about the
study and informed consents were taken from
each patient and their parents/legal guardians.
All the subjects were selected from nonextraction cases and all of them were treated by Edgewise fixed orthodontic mechanics.
Treatment of patients older than 18 years of
age was started with corticotomy procedure and
followed by RME. Treatment of patients who
were younger than 14 years of age started with
RME. The posteroanterior radiographs taken at
the beginning of expansion (T0), at the end of
expansion (T1), and two years after expansion
54
(T2) were digitized and evaluated. The mean
interval between T0 and T1 was 30,4 days for
RME group and 32,3 days for SARME group
RME group
The RME appliance was a tooth-borne Hyrax-type maxillary expander which was banded to maxillary first molar and first premolar teeth. Patients were instructed to activate
the jackscrew(GAC,Dentsply) 1 time per day
(0,25mm/day). Expansion was considered adequate when the occlusal aspect of the maxillary
lingual cusp of the permanent first molars contacted occlusal aspect of the mandibular facial
cusp of the permanent first molars. The amount
of overexpansion was designed to compensate for
relapse after expansion. The appliance was left in
place for 3 months after the completion of RME.
Surgically-assisted RME group (SARME)
A tooth-borne Hyrax appliance, using the
same design as the one in the RME group, was
cemented before the surgery to all the SARME
group patients.
The surgical interventions were carried out
under local anesthesia. All corticotomy operations were performed by the same oral surgeon
(B.G.). A lateral corticotomy technique which was
described by Glassman et al16 was used in all patients. After anesthesia was achieved, an incision
was made in the height of buccal vestibule from
the mesial aspect of the first molar to the distal aspect of the canine. The lateral maxillary wall was
exposed by mucoperiosteal elevation from the
piriform anteriorly across the zygomatic maxillary
buttress, then posterior to the pterygomaxillary
fissure via a subperiosteal tunneling technique. A
fissure bur was used to affect an osteotomy approximately 5 mm above the apices of teeth from
the piriform rim to the zygomatic maxillary buttress, ending just anterior to the period fissure.
Prophylactic antibiotics, nasal decongestants and
analgesics were prescribed to all patients.
The screws were activated immediately after
surgical procedure. Patients were instructed to
activate the jackscrew 1 time per day (0,25mm/
day). After the amount of overexpansion was
achieved, the appliance was left in place for 3
months. After 3 months, in both groups Hyrax
appliances were removed and replaced by transmaxillary arches for the rest of the conventional
orthodontic treatment. Roth prescription braces
(GAC) were administered to all the patients. At
the end of orthodontic treatment lower canine
to canine fixed lingual retainers were applied.
Patients used Hawley retainers for the maxillary
arch.
Cephalometric Evaluation
Posteroanterior cephalograms were obtained
before expansion (T0); after expansion (T1) and
two years after expansion (T2) from each of the
patients. The patients did not receive any brackets or wires on the maxillary arch until the T1
records were taken. Measurements were performed on posteroanterior cephalograms at T0,
T1 and T2 periods. The definition of the landmarks (Figure 1) and cephalometric analysis (Figures 2 and 3) were corresponded to those given
by Ricketts et al17 and Riolo et al18. Anatomic
tracings and location of dentoskeletal landmarks
were manually conducted by a single investigator
for both groups and measurements were done by
the same one (T.N.G)
Statistics
The mean values and standard deviation of
means were examined to compare the changes
both within and between the groups. Mann
Whitney-U test was performed to compare
changes from T0 to T2 between RME and
SARME groups and Friedman test was performed to determine the changes from T0 to T2
within each group. If a significant difference was
found, Bonferroni adjusted Wilcoxon signed rank
test was performed.
Reliability
Seven posteroanterior cephalograms from
each group were randomly selected, retraced
and remeasured by the same examiner 1 month
55
FIGURE 1
Cephalometric landmarks
1) Intersection of zygomaticofrontal suture and orbit(ZR,ZL)
2) ANS; Anterior Nasal Spine
3) U6; Upper first molar’s buccal crest
4) U6B; Upper first molar’s apex of buccal root
5) The points that zygomatic arch intersects tuberosity of
maxilla on the juguler process(JR, JL)
6) L6; Lower first molars buccal contour.
7) Antegonial notch’s lateral and inferior border.(AG, GA)
8) Me; Menton
later. No significant mean differences between
the two series of records were found, and the
reliability coefficients ( r ) ranged between 0,92
and 0,96.
Results
After RME in adolescents and SARME in
adults, the nasal cavity width and jugular width
increased. The changes were preserved in the
following two years in the adolescent group. The
maxillary intermolar width increased in both
RME and SARME groups and was preserved in
both of the groups in the following two years.
FIGURE 2
Skeletal measurements
1)Nasal cavity width: The distance between nasal cavity’s inner
cortical borders.
2)Mandibuler width: The distance between right and left
antegonial notch.
3)Right tuberosity distance: The distance between right frontal
facial plane and right tuberosity point.
4)Left tuberosity distance: The distance between left frontal
facial plane and left tuberosity point.
5)Juguler width: The distance between right and left juguler
points.
6)T angle: The angle between crista galli and tuberosity points.
7)TR angle: The angle between right frontal facial plane and
the plane between right tuberosity point and right antegonial
protuberantia .
8)TL angle: The angle between left frontal facial plane and
the plane between left tuberosity point and left antegonial
protuberantia.
Descriptive statistics for skeletal and dental measurements are shown in tables I -II.
Skeletal Measurements:
The nasal cavity width and jugular width increased during the T0-T1 period and was statistically significant in both groups.(Table I, ¶ =
p<.017) In the adolescent group, the increase in
nasal cavity width between T0-T2 period was
statistically significant as well.(Table I, †=p<.017)
56
gle, TL angle in both groups at either period.
(Table I, p>.05) Between groups, the only statistical significant change was in the T angle at all
periods.(Table I, p<.05)
Dental Measurements:
After RME and SARME there was a statistically significant increase in UL6 inclination at
T0-T1 periods. (Table II, ¶= p<.017) In adult
group, the UR6 and UL6 inclinations decreased
at T1-T2 periods.(‡=p<.017) The maxillary intermolar width increased at T0-T1 and T0-T2
periods in both groups. In adult group, it also
increased at T1-T2 period.(Table II, p<.05) The
increases in right molar relation at the T0-T1
and T0-T2 periods were statistically significant
in both groups. In addition, there was a significant increase in left molar relation at the T0-T1
period in adult group and at the T0-T1 and T0T2 period in adolescent group.
FIGURE 3
Dental measurements
Dental Measurements:
1)Maxillary intermolar width: The distance between maxillary
right and left I.molars’ buccal crests.
2)Mandibular intermolar width: The distance between
mandibuler right and left I. molars’ buccal crests.
3)Right molar relation: The overlap between maxillary right
I.molar and mandibular right I.molar.
4)Left molar relation: The overlap between maxillary left
I.molar and mandibular left I. molar.
5)UR6 inclination: The angle between the long axis of
maxillary right I.molar and midsagittal
plane.
6)UL6 inclination: The angle between the long axis of
maxillary left I.molar and midsagittal plane.
7)Right molar buccal vertical position: The distance from
maxillary right I.molar’s buccal cusp to Z horizontal plane.
8)Right molar palatinal vertical position: The distance from
maxillary right I.molar’s palatinal cusp to Z horizontal plane..
9)Left molar buccal vertical position: The distance from
maxillary left I.molar’s buccal cusp to Z horizontal plane.
10)Left molar palatinal vertical position: The distance from
maxillary left I.molar’s palatinal cusp to Z horizontal plane.
In the adult group, the jugular width showed an
increase at T0-T2 period.
There was no statistically significant change
in the mandibular width, right tuberosity distance, left tuberosity distance, T angle, TR an-
There was no statistically significant change
in the UR6 buccal vertical position, UR6 palatinal vertical position, UL6 buccal vertical position and UL6 palatinal vertical positions.(Table
II, p>.05) Between groups the UR6 and UL6
buccal and palatinal vertical position showed significant change at the T0 and T1 periods. In the
left molar relations and mandibular intermolar
width, there was a significant change at T1. The
UL6 inclination also showed significant change
at the T2 period.
Discussion
The objective of this study was to evaluate
and compare the dental and skeletal changes for
RME and SARME modalities during the expansion and two years after expansion. It’s important
to note that we are not inquiring wheter SARME
could be an alternative to RME. RME promotes
an increase in transverse dimensions and in the
perimeter of the upper dental arch width a real
gain of bone at the level of midpalatal suture 1,19
. When a transverse maxillary deficiency is present in the adult patient, it is complicated by the
ossification of the midpalatal, the maxillary but-
57
TABLE I
Comparison of skeletal measurements in RME and surgically assisted RME groups
*= p< 0.05
¶= p< 0.017(T0-T1)
†= p< 0.017(T0-T2)
‡= p< 0.017(T1-T2)
tress and the pterygomaxillary sutures. So, it is
unavoidable to use surgically assisted rapid maxillary expansion because of the patient’s skeletal
maturity4,14,15.
planned. Obliteration of the intermaxillary and
other circummaxillary sutures gradually occurs
with age and this closure has an effect on the
course of SARME 7,20.
Isaacson et al. 7 and Isaacson and Ingram 20
showed that the facial skeleton increases its resistance to expansion as it ages and matures. The
age of the patient is a major factor to be taken
into consideration when a SARME osteotomy is
Our study observing the semi-longitudinal
changes of the posteroanterior skeletal and
dental changes is of great importance for the
maintenance of the treatment outcome in both
SARME and RME patients.
58
TABLE II
Comparison of dental measurements in RME and surgically assisted RME groups
*= p< 0.05
¶= p< 0.017(T0-T1)
†= p< 0.017(T0-T2)
‡= p< 0.017(T1-T2)
59
Frontal cephalometry is an excellent method
for the diagnosis of face transverse deformities4,24.
Although it is widely employed by orthodontic
and surgical practitioners, few research papers
have used it for this purpose13,15,26 as this technique has been more commonly indicated for the
study of frontal asymmetries than deficiencies in
facial diameter. A frontal cephalogram may be
used not only as a preoperative estimation of the
transverse maxillary width but also as a complementary postoperative exam.
The initial measurements between the two
groups were similar in terms of skeletal and
dental cephalometric measurements (Table I
and Table II) Comparing the groups in general
there appears to be no big difference between
the behavior of the RME and SARME methods.
(Table I, Table II) When the results are examined
in detail, it is possible to see small and sometimes
statistically significant differences between the
groups. As a result, it can be concluded that both
approaches are effective in expanding a narrow
maxilla.
Nasal cavity width increased from T0 to T1
in both groups. There was no significant change
in adults in the following two years (Table I) but
the increase continued in the adolescents in the
following two years. (Table I) RME can be applied to the patients who have difficulty in nasal
breathing. While expanding the maxilla, RME
can also expand the nasal cavity and the increase
in nasal width will continue at least the following
two years.
There were no effects of RME or SARME on
mandibular transverse dimensions which was an
expected result.
There was no change in UR6 inclination in the
adult and the adolescent groups after the application of RME and SARME, but in UL6 inclination
there was a significant difference after expansion
between groups. (Table II) This finding showed
that during the expansion periods the maxillary
molars change their axial inclination seperately.
It can be due to the following two years period
fixed orthodontic treatment continued and those
teeth had buccal root torque. Northway and
Meade 25 stated that they had not observed any
buccal flaring in their studies in which different
approaches in maxillary expansion were compared. However, Wertz 5 mentioned that flaring
or tipping of the maxillary molars was a demonstrable and expected response to expansion.
Maxillary intermolar width increased with
RME and SARME treatment in both groups.
During the following two years with a little
amount of relapse tendency, the increase was
maintained. The amount of increase was small
in the adult group; and the relapse tendency was
more (Table II) so the amount of overtreatment
should be more in adults.
Bacetti et al 26 assessed the dental changes
through posteroanterior radiographs. When
comparing the early- and late-treated groups with
their respective controls, there was a significant
gain of the maxillary intermolar width (2,7 mm
and 3,5 mm respectively) in both treated groups.
However, in the early-treated group these changes were attributed to the significant expansion of
the skeletal maxilla (3.0 mm) against the control
group (0,9 mm). They concluded that changes
after RME were more of a skeletal nature before
pubertal peak and more dentoalveolar after pubertal peak 27,28.
Mandibular intermolar width increased in the
adult group and then relapsed in the following
two years.(Table II, p<0,05) During the RME
application there was no mandibular intermolar
width increase. During the following two years
mandibular intermolar width increased in the
adolescents; which can be indicative of the effect
of growth and development.
There was no statistical difference between
the RME and SARME groups and the following
two-years periods in UR6 buccal vertical, UR6
palatinal vertical, UL6 buccal vertical, UL6 palatinal vertical positions.( Table II, p>0,05) The
expansion treatment in adults and adolescents
had no effects on vertical dimensions.
The results related to vertical changes in the
RME group are of extreme clinical importance.
60
It’s known that RME increases lower anterior
facial height and inclination of the mandibular
plane and leads anterior bite opening because
of the downward maxillary displacement and extrusion of anchorage teeth.2,5,6,10,19,29-32 Furthermore, overcorrection of 2 to 3 mm during activation of the screw gives rise to occlusal interferences when the lingual cusps of maxillary teeth
occlude against the buccal cusps of mandibular
teeth 33 contributing to vertical increases.
Even though cephalometric studies show partial relapse of such alterations during the retention period 5 uncertainties of the longitudinal behavior of vertical facial dimensions is of concern
to the dentist, when performing RME in patients
with a long face and/or an excessively retrognathic profile34.
response between the adolescents and the
adults.
3) Nasal cavity width increased in both groups
which was more in the adolescents. So, RME
can be applied to the patients who have difficulty in nasal breathing.
4) Some overexpansion especially in SARME
applied in adult patients compared to RME
applied in adolescent patients is suggested
to eliminate the risk of relapse in both approaches.
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vertical and palatal vertical positions (Table II).
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Geliş Tarihi : 20.11.20098
Kabul Tarihi: 01.06.2009
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Received Date : 20 November 2008
Accepted Date : 01 June 2009
İLETİŞİM ADRESİ
İlken KOCADERELİ DDS, PhD
Hacettepe University Faculty of Dentistry Department of Orthodontics 06100 Sıhhiye - Ankara, TURKIYE
Home tel: + 90 312 223 71 37 Work Tel: + 90 312 311 64 61 Fax: + 90 312 309 11 38 ikocadereli@hotmail.com