Open Journal of Stomatology, 2011, 1, 165-167
doi:10.4236/ojst.2011.14024 Published Online December 2011 ( OJST
Published Online December 2011 in SciRes.
A simplified two-piece mandibular advancement appliance for
obstructive sleep apnea
Hiroshi Ueda1, Masato Ueno2, Genki Watanabe1, Atsushi Horihata1, Teruaki Seo2, Kazuo Tanne1
1Department of Orthodontics and Craniofacial Developmental Biology, Graduate School of Biomedical Sciences, Hiroshima Univer-
sity, Hiroshima, Japan;
2Chugokushiken Dental Laboratory Co., Hiroshima, Japan.
Received 21 July 2011; revised 23 August 2011; accepted 2 September 2011.
Nowadays mandibular advancement appliances (MA-
As) are available and distributed widely in the field
of dentistry for the treatment of snoring and ob-
structtive sleep apnea (OSA). However, a few stud-
ies discussed temporomandibular joint (TMJ) discom-
fort and masticatory muscle stiffness during wearing
MAAs are found. A new appliance that we introduced
in this pilot study has shown significant jaw move-
ment and could diminish TMJ and masticatory side
Keywords: Obstructive Sleep Apnea; Snoring; Mandi-
bular Advancement Appliances; Jaw Movement; Masti-
catory Muscle Stiffness
Currently, numerous mandibular advancement applian-
ces (MAAs) are available and distributed widely in the
field of dentistry for the treatment of snoring and ob-
structive sleep apnea (OSA) [1]. It is well known that
MAAs are classified roughly into two different types.
One is one-piece type and the other is two-piece one. Es-
pecially, the latter is widely used to improve temporo-
mandibular joint discomfort and masticatory muscle stif-
fness during wearing MAAs [2]. However, some conven-
tional two-piece type builds in thick springs or tube-and
piston assemblies lingually to the cheeks. OSA patients
may have difficulty tolerating this kind of two-piece MA-
This article is aimed to describe a simplified and com-
fortable two-piece MAA for OSA patients.
Basically, for the most part, the design of oral appliances
for OSA patients is derived from functional orthodontic
appliances to enhance mandibular growth in growing
patients with small and/or distally-located mandible. This
appliance consists of two occlusal splints held together by
an orthodontic wire (Figures 1). The splints are cons-
Figure 1. (a) Mandibular position shifted to the right
with MAA; (b) Mandibular rest position with MAA; (c)
Mandibular position shifted to the left with MAA.
H. Ueda et al. / Open Journal of Stomatology 1 (2011) 165-167
tructed of a 0.75 mm thick acrylic resin that provides full
occlusal coverage of teeth. A 0.0175 multi-stranded and
twist wire is attached on the buccal sides of the lower
splint (Figure 2). Patients can connect the lower splint
easily with the hook attached on the front portion of the
upper splint. The initial mandibular advancement was
defined as two-thirds of maximum mandibular forward
position with a 3 - 4 mm vertical opening at the anterior
teeth. This appliance can permit patients to freely move
the jaw horizontally (approximatel y 10 mm in the lateral
direction) and at the same time prevent the mandible to
move downward within 2 mm in the supine position by
means of an optoelectric jaw-tracking system with six
degrees of freedom (Gnathohexagraph system II, Ono-
sokki Co., Yokohama, Japan) (Table 1).
The mandibular position can also be titrated forward
from its initial position by adjusting the wire length on
the appliance.
Figure 2. Upper and lower plates of MAA.
Tab le 1. The distance of mandib ular movement with MAA dur-
ing maximum voluntary effort.
Jaw movement mm
Right-left direction Shift to the right
Shift to the left 11.9 +/– 1.99
11.4 +/– 1.82
direction Maximum jaw opening
Lateral jaw movement 1.63 +/– 0.95
0.77 +/– 0.25
(N = 5)
A 38-year-old male with a chief complaint of sleep frag-
mentation from OSA was referred to our clinic from a
cardiac physician. The patient’s weight, height and BMI
were 73 kg, 171 cm and 25 kg/m2, respectively.
The molar relationship on both sides was Angle’s
Class I, and mild crowding was found in the upper and
lower anterior teeth (Figure 3). Periodontal problems
and tem po romandibular joi nt disorders were not found.
Cephalometric analysis of the patient revealed a ske-
letal class II tendency (ANB = 5.5 degree) with large
mandibular pl ane angle (FMA = 42 degree) (Figure 4).
His apnea-hypopnea index (AHI) was 16.1 (Table 2).
Four months after using the two-piece MAA, the patient’s
initial symptoms were disappeared. Then, the physician
repeated PSG examination with the MAA in use. AHI
after the use of MAA was 9.2, substantially decreased
than 16.1, the initial value. Interestingly, one important
result of this case was the MAA therapy exerted a bene-
ficial effect on cardiac rhythm. This patient reported
much improvement in the number of events of high and
low heart rate according to the heart rate analysis (Table
2). In addition, after the treatment, he has no complaints
of temporomandibular joint pain and myofacial discom-
Figure 3. An initial occlusion.
Figure 4. An initial lateral cephalogram.
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H. Ueda et al. / Open Journal of Stomatology 1 (2011) 165-167
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Polysomnographic data
Table 2. Polysomnographic results before and after the use of
MAA. permits to move the mandible greatly in the lateral direc-
tion, not so much in the backward direction. Therefore,
undesirable side effects such as temporomandibular joint
disorders and masticatory dysfunction are less during
Before After
AHI (/hr)
Hypopnea (/hr)
Obstructive apnea (no.)
Central apnea (no.)
Mixed apnea (n o.)
Min imu m SaO2
Snoring (no.)
Mean Pulse B.P.M.
Number of events of high heart rate
Number of events of low heart rate
This appliance is efficient, inexpensive, breaking hardly
and friendly to intra- and extra-oral tissues. A further in-
vestigation focusing on the long-term effect of this ap-
pliance in more OSA patients should be attempted.
[1] US Food and Drug Administration (1999) Oral devices
cleared for treatment of snoring and/or obstructive sleep
apneas of 1/7/99. Food and Drug Administration, Wash-
ington, DC.
4. CONCLUSIONS [2] Lowe, A.A. (2000) Dental appliances for the treatment of
snoring and/or obstructive sleep apnea. Principles and
Practice of Sleep Medicine, 3rd Edition, M. H. Kryger, T.
Roth, W. C. Dement, W. B. Saunders Co., Philadelphia.
The materials used for the appliance are easy to obtain
and the fabrication is extremely simple. This appliance
APPENDIX Central apnea: absence of airflow due to lack of brea-
thing effort.
Apnea: cessation of ventilation for 10 seconds or longer. Mixed apnea: combination of obstructive and central
apnea with a central pattern evolving into an obstructive
Hypopnea: decreased airflow for 10 seconds or longer
and oxygen desaturation greater than 4%.
AHI (/hr): average number of apneas plus hypopneas
per hour of sleep. Minimum SaO2: minimum oxygen saturation level.
Mean Pulse B.P.M.: mean heart rate beats per minute.
Obstructive apnea: absence of airflow despite of per-
sistent breathing efforts.