Pacific Coast Society of Orthodontists Bulletin Summer 2023 - 64

Special Section: Treatment of Patients with Craniofacial Anomalies
Faculty Files
The Alveolar Cleft Revisited
Dr. Stephen L-K Yen
Los Angeles, CA
Dr. Stephen L-K Yen is a craniofacial orthodontist at
Children's Hospital Los Angeles and associate professor
at the University Southern California (USC)
Herman Ostrow School of Dentistry since 1989.
He is also involved in the management of trauma
cases at the USC-Los Angeles County Hospital and
conducts research at the Center for Craniofacial
Molecular Biology. In this article, Dr. Yen describes
his approach to the management of alveolar
clefting in patients with cleft lip and palate.
Dr. Kathryn Preston
Phoenix, AZ
PCSO Bulletin Section Editor
In cleft lip and palate, the purpose of an alveolar
bone graft is to bridge the cleft segments, support
the nose, provide bone for dental eruption, and
create the opportunity to close any existing fistulas.
From an orthodontist's perspective, the bone graft
should provide the biological framework for normal
tooth eruption and root development in skeletal
sites that were initially developing independently
as separate bony segments. Dr. Philip Boyne, who
introduced the secondary bone graft in 1972,1
terms of the alveolar cleft, the permanent teeth are
often erupting into cleft maxillary segments that
are missing bone. It is common to see rotated anterior
teeth and ectopic and angulated permanent
teeth near the borders of the alveolar cleft, especially
in unilateral cleft lip and palate. This combination
of large permanent teeth and missing bone leads to
dental crowding, even when 50%-70% of patients
with cleft lip and palate are congenitally missing
the lateral incisor.6
The missing alveolar bone and
lateral incisor can juxtapose the central incisor
against the canine after bone grafting, setting up
an eventual canine substitution of the missing lateral
incisor. We conducted a space analysis7
(Figure
asked
his readers to consider the graft not as a mechanical
strut but as living tissue that responds to the orthodontic
forces that are placed on it.2
When I graduated from orthodontic residency, I was
taught to prepare a patient with cleft lip and palate
by expanding the upper arch during the mixed
dentition when the permanent maxillary canine
root was one-half to two-thirds formed.3-5
That was
35 years ago. Although the rule is a good one
because this timing prepares a bone graft to receive
the erupting canine, it ignores the developing
lateral or central incisor on the other side of the
cleft, which erupts at ages 7-8 years. The two-thirds
canine root rule also assumes that all clefts are
equal, and a one-size-fits-all approach works for
every patient with a cleft lip and palate. Over the
years, we have modified this rule by trying to assess
and control for different variables that might lead
to a poor graft outcome. Some of the variables to
consider are provided next.
Paradoxical Dental Crowding
The cleft deformity represents missing tissue, such
as alveolar bone, teeth, muscle, and soft tissue. In
1) that compared the mesio-distal widths of the
unerupted permanent teeth (i.e., needed space) to
the length along a catenary curve from the mesial
of the first molar to the alveolar cleft margin (i.e.,
available space). There was a space shortage in
both the lesser and greater segments (more in the
greater segment) that was resolved when the segments
were expanded and grafted with additional
bone that made up the space difference. Maxillary
expansion can recreate a dental arch form and
provide arch length for correcting dental rotations.
In atypical cases, where the cleft malformation is
excessively large, these patients will be missing
more bone and teeth. The segments may need to
be compressed to make the cleft space manageable
with adequate mucosa for flap coverage.8
Type of Expansion Needed
Unilateral alveolar clefts tend to collapse anteriorly
and require differential anterior expansion, whereas
bilateral alveolar clefts may need symmetric expansion.
Symmetrical RPE expansion may overexpand
the molars in UCLP. Unlike the noncleft patient, the
patient with a complete cleft lip and palate presents
with a bony discontinuity in the maxilla and mobile
cleft segments that readily expand and align.
Differences in Expanders Versus No Expanders
Orthodontic repositioning is needed when the
maxillary segments have collapsed into the cleft
site. The fan-shaped rapid palatal expander,
quad-helix, W-arch, and spring-loaded telescopic
64
PCSO Bulletin Summer 2023
Pacific Coast Society of Orthodontists Bulletin Summer 2023

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