Orthotown November 2023 - 56

CONTINUING EDUCATION
expander). In addition, force magnitude
decreases as the appliance deactivates,
often requiring the clinician
to remove, reactivate and reinsert the
appliance midtreatment. Traditional
SME appliances also present various
clinical challenges, including irritation
and ulceration of the palatal tissue
and/or tongue, altered patient speech,
food impaction and decalcification
of banded anchor teeth. Therefore,
we must explore more comfortable,
predictable and efficient methods of
achieving slow orthopedic expansion
of the maxilla of preadolescent
patients in early mixed dentition.
Expansion of the mandibular arch
Mandibular arch expansion is a controversial,
polarizing and even taboo
concept not suited for the faint of
heart. It's important to note that when
we discuss " mandibular expansion " in
this context, we aren't discussing skeletal/orthopedic
expansion, because
the mandibular symphysis typically
fuses in humans within the first year
of life. Instead, we are referring to the
use of light forces to upright lingually
tipped molars and achieve dentoalveolar
expansion in the anterior and
middle thirds of the arch.
It has been known for decades that
this type of mandibular expansion
is safe, effective and stable. In 1962,
Walter concluded that mandibular
arch width could be expanded
permanently.17
used CBCT to evaluate dental and
skeletal changes after slow expansion
with a mandibular Schwartz appliance
and concluded that dentoalveolar
expansion of the mandibular arch
is both possible and stable.19
O'Grady et al. also evaluated the
Schwartz appliance and found that
expanding the mandibular arch of
preadolescent patients significantly
increases both mandibular arch width
and perimeter in the long term. Further,
it allowed for additional expansion
of the maxillary arch to correct
moderate tooth size/arch size discrepancies.20
This
is a very important point
that is frequently overlooked.
Maki and colleagues published a
study in 2006 describing the use of a
bihelix appliance to expand the mandibular
arch of patients ages 7-11.21
They concluded that lateral expansion
of the mandibular arch is both possible
and stable and can greatly reduce
the need to extract permanent teeth.
McNamara and Brudon reported similar
findings in 1993 and stated that
increasing mandibular arch size at
a young age is recommended so that
dentoalveolar, skeletal and muscular
adaptations can occur before the
eruption of the permanent teeth.22
In 2014, Kravitz proposed using
an Arnold expander to expand the
mandibular arch and, more specifically,
the intercanine width in patients
with moderate TSALD.23
He stated
In 1966, Schwartz and
Gratzinger presented the Schwartz
appliance to expand the mandibular
arch and recommended that the appliance
be turned slowly (typically once
every seven days) until the desired
amount of dentoalveolar expansion is
achieved.18
In 2010, Tai and colleagues
that for maximum efficacy, expansion
should begin before the eruption of the
permanent canines, lending credence
to the concept that we can use the primary
teeth to achieve dentoalveolar
expansion and thereby improve arch
perimeter and decrease the crowding
of the erupting permanent teeth.
NOVEMBER 2023 | 56 | ORTHOTOWN.COM
However, as with traditional SME
appliances, the traditional appliances
used for mandibular expansion are
often challenging for clinicians and
uncomfortable for patients. Therefore,
we must also explore superior methods
of slowly expanding the mandibular
arches of preadolescent patients in
early mixed dentition.
Braces and wires
Full-fixed appliances have many
advantages over removable and
bonded palatal and lingual appliances.
They are easy to place and use; are
well tolerated by patients; eliminate
the myriad clinical challenges associated
with fabricating, placing and
adjusting palatal/lingual appliances;
require fewer visits and less chair time
than banded or removable appliances;
and produce superior and more predictable
results. Archwires also allow
for the creation of more ideal arch
forms by improving incisor inclination
and increasing the expansion of
the anterior and middle thirds of the
arch, resulting in greater increases in
arch perimeter.24
Further, archwires can easily produce
the 250-500 g of force required
to achieve orthopedic expansion of
the maxilla in preadolescent patients.
Therefore, while the use of full-fixed
appliances to expand the arches of
preadolescent patients has not been
directly investigated in the literature,
it is logical to infer that the application
of a buccal force comparable
to the force applied on the palatal
using traditional SME and mandibular
expansion appliances would
have comparable biological and
clinical effects.
The following cases demonstrate
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