Pacific Coast Society of Orthodontists Bulletin Summer 2017 - 39

Faculty Files

Impacted Canines

Dr. Jae Hyun Park
Diplomate, American Board of
Orthodontics; Professor and Chair:
Postgraduate Orthodontic
Program, Arizona School of
Dentistry & Oral Health

Dr. Dawn Pruzansky
Administrative Director,
Postgraduate Orthodontic
Program, Arizona State School of
Dentistry & Oral Health

Introduction
An impacted canine is unable to erupt into its
proper position, although the etiology varies by
individual. The maxillary canine is the second
most commonly impacted tooth, preceded only
by the mandibular third molar.1 Palatal impaction
is seen more frequently than buccal impaction
and is twice as common in females. Buccal
impaction is usually due to inadequate space,
while palatal displacement is a positional anomaly.1 For this reason, the etiologies of buccal and
palatal impactions are thought to be different.
The two major theories associated with palatal
displacement of maxillary canines are genetic
theory and guidance theory. The genetic theory
proposes that palatally impacted canines have a
strong genetic component, and may be associated with retained primary canines, missing
or small lateral incisors, hypodontia, enamel
hypoplasia, or familial occurrence. Guidance theory suggests that the canine erupts along the
root of the lateral incisor, which serves as a guide
for eruption. If the lateral is missing or malformed, it will affect the canine eruption pattern.1
Diagnosis
Clinical signs of canine impaction include overretention of the primary canine, delayed eruption
of the permanent canine, absence of a labial
bulge, presence of a palatal bulge, and distal
crown tip of the lateral incisor.2 Although the
absence of a labial bulge may not necessarily
lead to impaction, a radiograph is warranted to
rule out any eruption disturbance.3
Radiographically, impacted canines can be diagnosed and localized using both intraoral (occlusal
and periapical) and extraoral (panoramic and
cephalometric) imaging techniques. More
recently, CBCT images have been used to evaluate the location of an impacted canine, as well as
to identify any root resorption of adjacent teeth.

Summer 2017  PCSO Bulletin

Treatment planning and surgical technique for
impacted canine retrieval has been thoroughly
discussed in the literature. In more complex
cases, ankylosis or transposition may occur. To
diagnose ankylosis, we typically look for loss of
movement, infraocclusion, lack of radiographic
periodontal ligament, tilt of adjacent teeth, and a
metallic sound upon tapping.4 In reality, accurate
clinical diagnosis is possible only by observing
the effect of orthodontic force application on the
suspected ankylosed tooth and adjacent teeth. If
the apex of the impacted canine is at the inverted
Y line of Ennis, which is defined as the region
where the cortices of the nasal cavity and the
maxillary sinus meet, then there is a high risk of
ankylosis.5
Clinical Cases
Palatal Displacement
Palatal impactions are encountered more frequently than buccal impactions. The type of surgical intervention is dictated by the position of
the crown in relation to the occlusal plane and
incisors.1,6 The open eruption techniques for
palatal impactions include the window technique or full flap. The window technique involves
the surgical removal of mucosa and bone immediately overlying the impacted tooth.3 It is used
when the canine is located immediately under
the surface. For a canine covered by a thicker surface, the full flap procedure is used. A full palatal
flap is made and the tooth is exposed. Before resuturing, a portion of the mucosa overlying the
tooth is excised.7 The closed eruption technique
can also be subcategorized. In a closed procedure,
a full flap is reflected in the thick keratinized
palatal mucosa; a small section of bone is
removed and a window is cut into the follicle,
just large enough to allow bonding of the eyelet
to enamel. The tunnel approach, introduced by
Crescini et al.8, uses the socket of the extracted

Table of Contents for the Digital Edition of Pacific Coast Society of Orthodontists Bulletin Summer 2017