Effects of surgically assisted rapid maxillary expansion on obstructive sleep apnea and daytime sleepiness

Abstract

The aim of the study was to evaluate the effects of surgically assisted rapid maxillary expansion (SARME) on obstructive sleep events and daytime sleepiness in adults with obstructive sleep apnea syndrome (OSAS).
Sixteen individuals (7 women/9 men) aged 40.2 ± 10.2 (range, 24.4 to 62.2 years) with maxillary transverse deficiency and OSAS (respiratory disturbance index [RDI] greater than 5) confirmed with full-night polysomnography (PSG) underwent SARME to evaluate its efficiency for OSAS treatment.
Several PSG parameters and the Epworth Sleepiness Scale (ESS) results were compared in selected individuals before and after they underwent SARME. An RDI reduction from 35.4 ± 38.5 to 16.0 ± 19.7 was found, corresponding to a mean decrease of 54.6 % (p = 0.0013). A 56.2 % (33.23 ± 39.5 to 14.5 ± 19.4, p = 0.001) decrease was found in the apnea-hypopnea index (AHI), in addition to decreases in the desaturation and microarousal rates, among other parameters. The ESS scores improved from 12.5 ± 5.3 to 7.2 ± 3.5 (p < 0.001).
SARME promotes an improvement in OSAS symptoms; decreases the rates of respiratory disturbances; microarousal, and desaturation; and reduces daytime sleepiness.

Full text

ORIGINAL ARTICLE
Effects of surgically assisted rapid maxillary expansion
on obstructive sleep apnea and daytime sleepiness
Pedro Pileggi Vinha
1,3
&Alan Luiz Eckeli
1
&Ana Célia Faria
1
&Samuel Porfirio Xavier
2
&
Francisco Veríssimo de Mello-Filho
1
Received: 10 March 2015 /Revised: 12 May 2015 /Accepted: 2 June 2015
#Springer-Verlag Berlin Heidelberg 2015
Abstract
Purpose The aim of the study was to evaluate the effects of
surgically assisted rapid maxillary expansion (SARME) on
obstructive sleep events and daytime sleepiness in adults with
obstructive sleep apnea syndrome (OSAS).
Methods Sixteen individuals (7 women/9 men) aged 40.2±
10.2 (range, 24.4 to 62.2 years) with maxillary transverse
deficiency and OSAS (respiratory disturbance index [RDI]
greater than 5) confirmed with full-night polysomnography
(PSG) underwent SARME to evaluate its efficiency for OSAS
treatment.
Results Several PSG parameters and the Epworth Sleepiness
Scale (ESS) results were compared in selected individuals
before and after they underwent SARME. An RDI reduction
from 35.4±38.5 to 16.0±19.7 was found, corresponding to a
mean decrease of 54.6 % (p=0.0013). A 56.2 % (33.23±39.5
to 14.5±19.4, p=0.001) decrease was found in the apnea-
hypopnea index (AHI), in addition to decreases in the
desaturation and microarousal rates, among other parameters.
The ESS scores improved from 12.5±5.3 to 7.2± 3.5
(p<0.001).
Conclusions SARME promotes an improvement in OSAS
symptoms; decreases the rates of respiratory disturbances;
microarousal, and desaturation; and reduces daytime
sleepiness.
Keywords Surgically assisted rapid maxillary expansion .
Adults .Sleep apnea syndrome .Obstructive sleep apnea
syndrome .Disorders of excessive somnolence
Abbreviations
SARME Surgically assisted rapid maxillary expansion
OSAS Obstructive sleep apnea syndrome
CIEDEF Comprehensive Center for the Study of Defects
of the Face (Centro Integrado de Estudo dos
Defeitos da Face)
HC-FMRP-
USP
Teaching Hospital of the School of Medicine of
Ribeirão Preto, University of São Paulo (Hos-
pital das Clínicas da Faculdade de Medicina de
RibeirãoPretodaUniversidadedeSãoPaulo)
PSG Polysomnography
ESS Epworth Sleepiness Scale
RME Rapid maxillary expansion
BMI Body mass index
TST Total sleep time
AHI Apnea-hypopnea index
RERAI Respiratory effort-related arousals index
RDI Respiratory disturbance index
PLM index Periodic limb movement index
Introduction
Obstructive sleep apnea syndrome (OSAS) is characterized by
partial or complete upper airway obstruction during sleep and
affects up to one third of the adult population [1]. This syn-
drome is associated with clinical conditions such as
*Pedro Pileggi Vinha
pvinha@usp.br
1
School of Medicine of Ribeirão Preto, University of São Paulo, Av.
Bandeirantes, 3900, Ribeirão Preto, São Paulo, Brazil 14049-900
2
School of Dentistry of Ribeirão Preto, University of São Paulo,
School of Dentistry, Campus USP, Ribeirão Preto, São
Paulo 14040-904, Brazil
3
Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, Brazil 14049-900
Sleep Breath
DOI 10.1007/s11325-015-1214-y

hypertension and type 2 diabetes [2,3] and has extensive
consequences, such as reduced quality of life and increased
mortality [4,5].
OSAS has multifactorial etiology that includes factors re-
lated to facial orthopedics, soft tissues, and environmental
factors. Among factors related to bone structure, the relation-
ships between OSAS and mandibular growth deficiencies,
bimaxillary retrusion, and sharp bending of the base of the
skull have already been described [6–9]. Regarding factors
related to soft tissues, disproportions between the tongue vol-
ume and the oral cavity and the flaccidity of the lateral pha-
ryngeal walls seem to increase the likelihood of developing
OSAS [10]. Among environmental factors, obesity has a very
significant role [11] in the genesis of OSAS.
Among orthopedic factors, maxillary transverse deficiency,
also known as maxillary atresia, has been reported as a possi-
ble etiological agent of OSAS [6,12,13]; in some cases,
maxillary transverse deficiency may be the main factor
[13–18]. Maxillary transverse deficiency is defined as a
dentofacial deformity characterized by narrowing of the upper
dental arch in the transverse direction, decreased distance be-
tween the posterior teeth on opposite sides, and consequent
uni- or bilateral posterior crossbite or even normal occlusion
in the case of concomitant mandibular transverse deficiency.
In addition to the effects on occlusion, maxillary transverse
deficiency may cause an increase in the nasal resistance to
airflow [19] and posterior tongue displacement, thus facilitat-
ing pharyngeal collapse [14].
The most effective treatment for maxillary transverse
deficiency in children and adolescents is rapid maxillary
expansion (RME). This procedure consists of the place-
ment of an intraoral appliance supported by the posteri-
or teeth and expanding it daily by 0.4 to 0.8 mm. This
rapid opening separates the midpalatal suture and ex-
pands the oral cavity.
However, RME is only recommended for individuals who
are still growing; once the sutures of the jaws are fused, sur-
gical osteotomies are required to allow the free mobilization of
bone segments and the subsequent activation of the appliance.
Such surgery is defined as surgically assisted rapid maxillary
expansion (SARME).
First described in 1938 [20], SARME is a safe and effective
technique for treating maxillary transverse deficiency and for
obtaining space for teeth alignment because it increases the
perimeter of the upper dental arch. SARME complications are
rare and include hemorrhage, gingival recession, infections,
and tooth devitalization [20]. After the intervention, orthodon-
tic treatment is required to correct the spacing between the
maxillary central incisors. The transverse maxillary expansion
is significant and usually allows better dental accommodation,
improved occlusion, and an expanded oral cavity. We hypoth-
esized that a larger oral cavity favors better tongue position-
ing, promoting a greater posterior pharyngeal space and the
consequent reduction of the obstruction in patients with
OSAS.
The present study aimed to evaluate the effects of SARME
on polysomnographic parameters and excessive sleepiness in
adult patients with OSAS and maxillary transverse deficiency.
Methods
This prospective clinical trial was approved by the Ethics
Committee of the Teaching Hospital of the School of Medi-
cine of Ribeirão Preto, University of São Paulo (Hospital das
Clínicas da Faculdade de Medicina de Ribeirão Preto da
Universidade de São Paulo [HC-FMRP-USP], no.
01270004000-10), and all patients signed an informed con-
sent form.
The participants in this study were patients at the HC-
FMRP-USP Comprehensive Center for the Study of Defects
of the Face (Centro Integrado de Estudo dos Defeitos da Face
[CIEDEF]) and had complaints of occlusal problems, snoring,
and daytime sleepiness. The participants were consecutively
recruited from August 2011 to February 2014.
The inclusion criteria were patients with maxillary trans-
verse deficiency with a distance between premolars of less
than 36 mm, a unilateral or bilateral posterior crossbite
(Fig. 1), and OSA (respiratory disturbance index (RDI) >5)
confirmed with full-night polysomnography. Individuals with
large facial bone abnormalities or a body mass index over 35
were excluded.
OSAS was defined according to the International Classifi-
cation of Sleep Disorders 2nd ed. [21].
The full-night polysomnography (PSG) studies were per-
formed at the Clinical Neurophysiology Laboratory using Bi-
oLogic equipment (BioLogic Vision, Inc., Natus, San Carlos,
CA, USA). The parameters obtained included electroenceph-
alograms, electrocardiograms, electrooculograms, mental and
lower limb electromyograms, pulse oximetry, abdominal and
thoracic effort (using inductance plethysmography belts), and
nasal airflow (using a thermocouple and nasal pressure). All
technical parameters were measured in accordance with the
Manual of the American Academy of Sleep Medicine, 2007,
using the 4B criteria for hypopnea [22]. The neurologist re-
sponsible for the PSG analysis did not know whether the tests
were being performed before or after the intervention.
Daytime sleepiness and anthropometric data, such as BMI,
neck circumference, and dental arch moldings, were collected
before and at the end of the intervention. To assess daytime
sleepiness, the Epworth Sleepiness Scale (ESS) [23,24]was
used. Models of the dental arches were used to measure the
transverse gain in the upper arch. The standard measurement
was the distance between the first premolars and the first mo-
lars on each side.
Sleep Breath

A Hyrax maxillary expander appliance was installed in all
participating individuals and was usually banded on the first
premolars and first molars (Fig. 2).
All the subjects underwent the same surgical technique
performed by the same team. The surgical technique used
was a variation of the method described by Bell and Epker
in 1976; it consisted of a Le Fort I osteotomy with separation
of the pterygoid apophysis of the sphenoid bone and another
osteotomy between the upper central incisors. An osteotomy
to release the maxilla from the pterygoid plate was used
to promote a medial bone disjunction of the anterior
and posterior maxilla. This method promotes a more
parallel spacing between the sides of the maxilla; when
no disjunction is performed, the maxillary opening tends
to be more anterior [25–27], which may compromise the
results.
Five days after the surgery, the appliance was activated,
and a half-turn of the screw (0.4 mm) was performed every
12 h according tothe activation protocols for facial distraction
osteogenesis [20]. The total activation period was individual-
ized for each patient. All the patients had the crossbite issue
resolved according to the reference standard of the palatal
(internal) cusp of the upper teeth on the buccal (external) cusp
of the lower teeth; the crossbites were slightly overcorrected.
After the opening process was completed, the screws were
locked; on average, we waited 150 days to remove the
appliance.
A second full-night PSG was performed 355±158 days
after surgery. We chose to perform the second PSG later (ap-
proximately 1 year after surgery) to ensure the complete
stability of the structures that had been moved and to incor-
porate any losses or relapses.
Statistical analysis
Because the PSG data were not normally distributed, the non-
parametric paired Wilcoxon test was used. For anthropometric
measurements, dental changes, and the ESS, the paired ttest
was used. All values are presented as the means± standard
deviations, and the significance level was set at p<0.05.
Results
Sixteen individuals participated in this study, including 7
women and 9 men aged 40.2± 10.2 years old (minimum
24.4 years and maximum 62.2 years).
The ESS displayed an initial mean value of 12.5±5.3; after
the intervention, the mean value was 7.2±3.5 (p<0.001;
Fig. 3).
Table 1shows the PSG values before and after the
intervention.
The apnea-hypopnea index (AHI) exhibited a mean reduc-
tion of 56.2 % (pre 33.2±39.5 and post 14.5±19.4, p<0.001).
This improvement of obstructive events was observed in both
rapid eye movement (REM) sleep and non-REM (NREM)
sleep.
Figure 4shows that similar to the AHI, the RDI also de-
creased significantly, from 35.4±38.5 to 16.0±19.7
(p<0.001).
Fig. 1 Maxillary transverse
deficiency (a) and bilateral
posterior crossbite (b)
Fig. 2 Pre-SARME maxillary transverse deficiency (a) with a Hyrax expander in place (b) and post-SARME (c)
Sleep Breath

Table 1also shows that there was a significant decrease in
the microarousal index. The initial value was 41.5± 25.2; after
SARME, it decreased to 20.8 ±13.5 (p=0.014), reducing sleep
fragmentation.
Another polysomnographic variable that improved signifi-
cantly was the desaturation index. A decreased index was
noted in the second PSG. The initial value of 21.3 ± 31.6
dropped to 14.8±25.9 (p=0.047).
Fig. 3 Box plot of the ESS
before and after SARME
Tabl e 1 PSG variables assessed pre- and post-SARME
Pre-SARME 95 % CI Post-SARME 95 % CI Diff % pvalue
TST (min) 363.1±50.03 330.35–390.06 336.9±101.1 271.7–396.5 −7.21 0.519
Sleep efficiency % 82.0±11.58 74.27–87.49 86.6±8.1 81.0–90.9 5.67 0.216
Arousal index 41.57±25.2 9.1–21.90 20.8±13.5 5.2–36.4 −49.9 0.014
N1 (% TST) 12.4±5.8 8.9–16.00 11.8± 6.8 7.6–16.2 −5.0 0.404
N2 (% TST) 46.4±12.2 39.6–54.66 47.4±7.2 43.0–52.6 2.2 0.606
N3 (% TST) 20.9±8.8 15.2–26.11 23.7±8.9 18.7–29.3 13.2 0.433
REM (% TST) 20.1±9.9 13.6–25.72 17.0±6.9 13.1–19.3 −15.3 0.252
Supine (% TST) 44.4±26.2 23.9–69.94 42.5±39.8 20.2–71.7 −4.4 0.413
Apnea index 15.7± 34.7 3.3–39.08 5.5±12.1 1.0–13.7 −64.6 0.107
Hypopnea index 18.2±22.7 6.7–34.02 9.1± 10.9 3.6–16.7 −49.9 0.005
AHI 33.2±39.5 14.0–60.92 14.5± 19.4 4.6–28.0 −56.2 0.001
NREM AHI 28.1±30.4 11.2–53.39 10.8±21.3 3.4–30.3 −61.6 0.008
REM AHI 29.1±39.3 15.7–66.88 17.1±19.6 6.1–30.8 −41.0 0.013
RERAI 2.2±4.0 0.3–3.54 1.5±2.1 0.2–2.8 −30.7 0.939
RDI 35.4±38.5 16.0–62.17 16.0±19.7 6.0–29.7 −54.6 0.001
Desaturation Index 21.3±31.6 0.0–46.12 14.8±25.9 1.6–31.5 −30.7 0.047
Minimum O
2
81.3±9.2 75.0–86.12 84.3± 5.7 80.6–87.6 3.6 0.803
Mean O
2
92.7±5.4 89.0–98.62 94.0± 1.6 92.8–94.7 1.4 0.607
PLM index 4.4±6.3 0.0–4.59 4.1±8.2 2.2–7.7 −7.1 0.343
TST total sleep time, AHI apnea-hypopnea index (number of apneas and hypopneas as a function of TST), RERAI number of arousals relative to
respiratory effort as a function of TST, RDI respiratory disturbance index (AHI+RERAI), PLM periodic limb movement
Sleep Breath

Anthropometric data, BMIs and neck and waist circumfer-
ences, were also evaluated before and after SARME. Table 2
shows that these values did not change significantly.
The pre- and post-SARME models of the maxillary arch
indicated that there was an expansion of the maxillary arch
that extended the oral cavity in the transverse direction
(Table 3).
Discussion
Improvements in several PSG parameters and daytime sleep-
iness in patients with OSAS who underwent SARME were
observed in this study.
Despite some studies that report improvement of OSAS in
children who undergo RME [28], we did not find any specific
study on the effects of SARME on OSAS and ESS, especially
in adult patients.
A study with younger subjects (15.8 to 39.4 years old)
shows the effect of SARME on sleep architecture, including
obstructive events, but it includes participants with or without
OSAS (only 7 of the 28 patients had an AHI >5), which blends
the sample because the PSG results were obtained from all
participants [29]. Another study, in addition to using relatively
young patients (14 to 37 years), blended expansion techniques
with and without surgical assistance (six surgically assisted
and four nonsurgically assisted), making the results difficult
to interpret. Additionally, that study used a different technique
than the one used in the present study [14]. Thus, the compar-
ison between these studies becomes inaccurate.
In another study, RME (maxillary expansion without sur-
gical assistance) was used in 42 children (from 6 to 13 years
old, mean 7 years old) with OSAS; that study showed an AHI
improvement from 12.7±2.5 to 0.5±1.2 and significant im-
provements in desaturation [28]. However, these results can-
not be compared with those of the present study because of the
differences in the participant ages and in the technique used
for maxillary expansion.
However, this study and our results raise an interesting
question about the capacity of soft tissues to adapt to bone
changes and thus promote improvement of OSAS. In children
or young individuals with great tissue plasticity, soft tissues
are expected to proportionally accompany bone movement;
therefore, gains in the airspaces of the mouth and oropharynx
are expected. However, one may question whether such an
effect would occur in adults and older individuals, in whom
possible tissue laxity could negate any changes in soft tissues.
Because OSAS is predominantly found in people aged
35 years and older, is progressive, and increases in incidence
andseveritywithage[30,31], the results of interventions in
this population could be nonsignificant. Thus, only individ-
uals in the age group for which OSAS is most common were
included in the present study, and even with a mean age of
40.2±10.2 (24.4 to 62.2 years), a good response was ob-
served; consequently, significant improvements in breathing
patterns during sleep and daytime sleepiness were noted.
Regarding PSG variables, we observed significant reduc-
tions in AHI, RDI, and the desaturation and microarousal
indices after SARME. The reduction inthe number of obstruc-
tive respiratory events was greater than 50 %, and the results
were similar during REM and NREM sleep. There were no
Fig. 4 Pre- and post-SARME RDI
Tabl e 2 Anthropometric data pre- and post-SARME
Pre 95 % CI Post 95 % CI Diff % pvalue
BMI 29.8±4.4 32.1–27.4 29.9±5.3 32.8–27.1 0.5 0.667
Neck (cm) 40.8±3.3 42.5–39.0 40.5±3.4 42.3–38.6 −0.7 0.415
Waist (cm) 103.8±11.2 111.6–99.3 105.5±11.4 42.5–39.0 1.6 0.235
BMI body mass index, Neck neck circumference, Wais t waist circumference
Sleep Breath

significant changes in sleep stages and sleep efficiency after
the intervention. Some sleep parameters that could influence
this analysis, such as time spent in the supine position and the
proportions of REM and NREM sleep, did not differ before
and after the intervention.
Using values obtained from a systematic review with a
meta-analysis [32], we were able to compare the AHI reduc-
tion obtained in the present study (56.24 %) with that obtained
using other surgical techniques. The mean decreases in the
AHI were 87 % for maxillo-mandibular advancement surger-
ies (nine studies), 33 % for uvulo-palato-pharyngoplasty (15
studies), 18 % for laser-assisted uvuloplasty (two studies),
34 % for radiofrequency surgery (two studies), and 26 % for
palatal implants (two studies).
However, the aim of the present study was not to compare
OSAS treatment methods but to demonstrate the ability of
SARME to reduce or resolve OSAS in adults. Thus, we call
our colleagues’attention to the fact that the correction of max-
illary transverse deficiency in OSAS is an important method
for improving treatment results or even fully curing this
condition.
Regarding daytime sleepiness, a decrease in ESS scores
from 12.5± 5.3 to 7.2 ±3.5 (p≤0.001) was observed, indicating
a return to normal values. The possibility of a placebo effect
relative to daytime sleepiness cannot be ruled out because
such an effect is also possible with conservative treatments,
such CPAP use [33].
The distances between the first premolars and the first mo-
lars were consistent with other studies; they increased by 5.4
and 5.5 mm, respectively [34,35]. Despite the few millimeters
of linear gain obtained, this difference corresponds to an av-
erage of 15 to 25 % of the transverse gain and occurs through-
out the dental arch, which indicates an important intraoral
volume gain. Thus, we believe that the tongue will advance
into the now-enlarged oral cavity and that eventually, there
will be an important gain in the retro-lingual area of the phar-
ynx, thus decreasing the obstructive events during sleep.
The participants’anthropometric data (BMI, neck circum-
ference, and waist circumference) did not change significant-
ly, i.e., they remained relatively stable before and after the
intervention. Therefore, we believe that the improvements in
PSG patterns and sleepiness are not a result of changes in
these parameters, which are presented in Table 2.
The improvement of OSAS as a result of SARME most
likely occurs for two reasons: (1) the expanded posterior air-
way space thatresults from the tongue’s ability to advance into
the oral cavity as a result of the increase in the tooth and bone
perimeter promoted by surgical maxillary expansion [14,
36–38] and (2) the decreased resistance to airflow through
the nose as a result of the expanded nasal cavity. Given that
increased resistance to airflow through the nose is another
factor associated with OSAS [39], the improvement in ob-
structive respiratory events after SARME is, at least in part,
secondary to the decreased nasal resistance and the expanded
internal space [25].
Another advantage of the SARME treatment for OSAS is
the possibility of combining it with other procedures, such as
maxillo-mandibular advancement, CPAP, or intraoral appli-
ances, thus reducing the discomfort caused or exacerbated
by excessive pressure or mandibular advancement.
This study was not able to define the factors that could
predict successful OSAS treatment with SARME. Therefore,
further studies should be conducted to quantify the actual role
of maxillary transverse deficiency in the development of
OSAS and whether correction in young individuals could pre-
vent OSAS.
A major objective of this study is to include SARME as a
therapeutic alternative that can be used to treat or attenuate
OSAS and to quantify the effectiveness of this procedure in
the treatment of adults with this syndrome.
This study demonstrated that SARME was effective for
reducing OSAS in patients with maxillary transverse deficien-
cy and crossbite, reducing daytime sleepiness, and promoting
correct dental occlusion.
Acknowledgments The authors thank the São Paulo Research Foun-
dation (Fundação de Amparo à Pesquisa do Estado de São Paulo
[FAPESP]) for their financial support of this study. This study was funded
by the government of the State of São Paulo through the São Paulo State
Research Foundation (FAPESP).
Ethical standards Clinical trial registered with the National Health
Council/National Ethics and Research Council (Conselho de Nacional
de Saúde/Conselho Nacional de Ética em Pesquisa [CONEP]), http://
portal2.saude.gov.br/sisnep/menu_principal.cfm, CAAE 0127.0.004.
000-10
Conflict of interest There are no conflicts of interest or funding by the
industry or related individuals.
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Sleep Breath

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