Yomas

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Journal

CLINICAL
SECTION

of Orthodoniic.s.

V o l . 35. 2 0 0 8 . 5 - 1 5

A case of anterior open bite with
severely narrowed maxillary dental
arch and hypertrophic palatine tonsils
Kotaro Tanimoto, Aya Suzuki, Yuki Nakatani, Tamami Yanagida, Yuki Tanne,
Eiji Tanaka, Kazuo Tanne
Oriluidoniics und Craniofatial Developmenlal Biology, Hiroshima University,Hiroshima, Jupan

This case report describes an adolescent patient with an open bite and severely narrowed maxillary dentition and hypertrophic
palatine tonsil.s. treated etllciently with rapid maxillary expansion ( RME) and subsequent orthodontic tooth alignment using
Hxcd appliances. T he treatment demonstrates that R ME can be elTectivc for the correction o fa severely narrowed ma.\illary
arch,as well a s. in this case, the correction of an a nterior open bite in an adolescent patient where n o substantial vertical
skeletal discrepancy existed.
Key nvrdi: A nterior open bite, orthodontic treatment, rapid maxillary expansion, narrowed ma.\ilhiry dentition, hyperlrophie
palatine tonsils
Received 7th September 2006: uirepieil 29th July 2007

Introduction
Ati open bite is frequentlyaccompanied with a
narrowed maxillary dentition, which may result from
mouth breathing. There are various morphological
features of skeletal open bite such as negative overbite,
large Frankfort mandibular planes angle (FMPA).
mesially inclined molar leeth, narrow maxillary dentition, short ramus height, and downward and backward
rotation of the maxillomandibular skeleton.' Among
them, thenarrowed maxillary dentition associated with
a posterior crossbite is a major problem for o rthodontic
treatment, because the relapse of the transverse
maxillary dimension may affect the vertical skeletal
discrepancy.
Patients with an open bite and with a narrowed
maxillary dentition may be subject t o mouth breathing
resulting from nasopharyngeal obstruction such as
adenoid hypertrophy.^Constriction of the posterior
airway and the subsequent mouth breathing have been
put forward as a mong the critical factors that may cause
open bite.""* Hypertrophic tonsils are a nasopharyngeal
dysplasia which narrow the airway and produce
difliculty in nasal breathing.
In orthodontic treatment during the mixed dentition, dentoalveoiar open bite tnay be corrected by
eliminating localenvironmental causes such as parafunctional habits. However, continuing long-term oral
Address for correspondence: Dr Kotaro Tanimoto, Orthodontics
and Craniofacial Dcvclopmciual Biology. Hiroshima University,
i-2-3 Kasumi, Minami-ku. Hiroshima 734-8553. Japan.
Email; lkolaro@hiroshima-u.ac,jp
I'' 2008 Briltsh Orthodontic Society

habits exert more severe influences on dentoalveoiar
morphology.Given these considerations, the open bite associated
with a severely narrowed maxillary dentition often
presents a difficulty for o rthodontic treatment. Rapid
maxillary expansion ( RME) is an effective approach for
increasing the transverse dimension of the maxillary
arch, and has been used frequently in growing
patients.'*""'' It is generally suggested that R ME is
appropriate forpatients with a full-cusp crossbite
associated with a skeletal component, and some degree
of dental as well as skeletal constriction with no
preceding dental expansion.''
The purpose of this article is to report a case of open
bite with a severely narrowed maxillary dentition and
hypertrophic palatine tonsils treated with R ME and
subsequent orthodontic tooth alignment.

Case report
A13-years, sevcn-month-old female patient had an
anterior open bite with a severely narrowed maxillary
dentition (Figure I). She complained of occlusal, functional and aesthetic disturbances d ue to the a nterior
open bite. The molar relationship was Class 1 on the
right side and Class II on the left. Overjet a nd overbite
were 6.0 and - 6 . 5 mm respectively.

DOl 10.1179/146531207225022356...