134 Orthodontics
October 2019
Enhanced CPD DO C
Naeem Adam
Andrew Flett and Cara Sandler
Multiple Unerupted Teeth
– an Interesting Challenge
Abstract: This paper describes primary failure of eruption and presents some of the theories about the aetiology of this clinical condition.
It also covers single ankylosed teeth as well as cases that present with multiple unerupted teeth. The various approaches to the clinical
management of this not uncommon problem are discussed, along with the pros and cons of some of these techniques.
One difficult clinical challenge is documented, where a 14-year-old patient presented with 19 unerupted permanent teeth and, with the
help of rare-earth magnets and upper and lower fixed appliances, within a two-year period a good result was achieved.
CPD/Clinical Relevance: Clinicians encounter teeth that have failed to erupt on a regular basis. Appropriate diagnosis and treatment
planning of these cases, and subsequent effective clinical management, is imperative to ensure the most favourable outcome for our
patients.
Ortho Update 2019; 12: 134–139
Permanent teeth may fail to erupt because
of obstruction, or disruption, of the
eruptive mechanism. Eruption may be
obstructed by the presence of pathology,
ectopic tooth position, interferences from
adjacent teeth or lateral forces from the
tongue.1 Teeth may also fail to erupt due
to primary failure of eruption (PFE) or
ankylosis. The latter is defined as the fusion
of cementum to bone in at least one area
lacking a periodontal ligament space.2
Primary failure of eruption (PFE)
is defined as incomplete tooth eruption
despite the presence of a clear eruptive
pathway.1 There is no ankylosis and it is the
eruptive mechanism itself that is disturbed.2
This article will review the literature on PFE
and failure of eruption from ankylosis. We
also present a case of multiple unerupted
teeth, treated with the use of neodymium
iron boron magnets, as well as the more
conventional deployment of gold chains to
facilitate orthodontic traction.
Establishing the correct
diagnosis forms the basis of satisfactory
management of unerupted teeth. It is
vital to distinguish obstructive failure
of eruption, PFE and isolated ankylosis.
Not doing so may jeopardize successful
orthodontic management and potentially
cause harm to the patient. This is
particularly pertinent in cases of PFE, where
the injudicious application of traction
may precipitate ankylosis of the offending
tooth and consequent intrusion of adjacent
normal teeth.3
Primary failure of eruption
The term PFE was coined by Proffit and
Vig in their seminal research on the topic.4
It is a rare condition with a prevalence of
0.06%.5 Subsequent research has refuted
some of their initial observations, but the
literature demonstrates consensus on the
following features:1,2,6
 Posterior teeth are more frequently
affected than anteriors;
 Teeth posterior to the most anteriorly
affected tooth may be involved;
 Affected teeth may completely fail to
erupt, or may initially erupt through the
oral mucosa, before ceasing to erupt
further;
 The occlusion manifests as a lateral open
bite;
 Involvement can be unilateral or bilateral;
 Application of orthodontic forces to
the affected teeth sometimes precipitates
ankylosis rather than normal tooth
movement;
 PFE is associated with a mutation in the
parathyroid hormone 1 receptor (PTH1R)
gene.
Raghoebar et al subdivided
PFE into primary and secondary retention;
primary if the tooth failed to erupt, and
secondary if there was cessation after initial
penetration through the oral mucosa.7
Frazier-Bowers et al described three
different forms of PFE:8
 Type I, where all affected teeth have
a similar lack of eruptive potential and
a posterior open bite establishes with
worsening severity from anterior to
posterior;
 Type II, where a more varied eruption
potential is seen between the affected
teeth. In such cases, a tooth distal to the
Naeem Adam, BDS(Hons) MaxFac DCT2, Leeds Dental Hospital (email: naeem.i.adam@gmail.com), Andrew Flett, BDS, MJDF RCS,
MClinDent, MOrth RCS, Consultant Orthodontist, Nottingham University Hospital and Cara Sandler, BDS MaxFac DCT1, Royal Sussex
County Hospital, Brighton, UK.
Downloaded from magonlinelibrary.com by 128.243.044.244 on November 8, 2019.
Orthodontics 135
October 2019
most mesial affected tooth may show
greater, but still inadequate, eruptive
potential;
 In Type III, subjects have both Type I and
Type II tendencies co-existing in different
quadrants.
Several systemic or syndromic
conditions, such as cherubism and
cleidocranial dysplasia, have failure of tooth
eruption as an identifying feature, and must
be excluded when establishing a diagnosis
of PFE.1 A family history of PFE appears
to be a risk factor for its development,
and inheritance appears to be autosomal
dominant with variable expressivity.9
Earlier research found the level of dental
anomalies, such as hypodontia, to be
considerably higher than average in
individuals with PFE, but more recent
research refutes this.1,6
PFE appears to be associated
with a mutation in the PTH1R gene and,
consequently, genetic testing may assist in
early and accurate diagnosis.10
Even in the absence of a known
genetic, pathological or environmental
factor responsible for failure of tooth
eruption, a true definitive diagnosis of PFE
may only ever be given retrospectively,
after attempts at orthodontic extrusion of
the affected teeth have failed. Management
of PFE is made difficult by the tendency
for affected teeth to ankylose when
orthodontic forces are applied.1 The
literature describes various techniques from
coronal build-ups of the affected teeth
to segmental osteotomy, but treatment
in severe cases is invariably complex and
often multidisciplinary.3 The case presented
here responded well to orthodontic
traction, excluding a diagnosis of PFE.
Figure 1. OPT showing multiple unerupted teeth.
Ankylosis and failure of
eruption
Isolated ankylosis is a rare condition
with a similar presentation to PFE.
A diagnostic feature distinguishing
between the two is that ankylosis
typically affects a single tooth, with
distal teeth being unaffected.1 This
naturally makes diagnosis difficult in
a child in the mixed dentition, as one
cannot be certain of the status of the
unerupted teeth. Partially erupted teeth
that are ankylosed will exhibit a dull
metallic sound when percussed. These
teeth cease to erupt, drift or move,
despite normal adolescent growth or
orthodontic traction. They may further
disturb the occlusion by allowing
adjacent teeth to tilt and opposing
teeth to overerupt. Radiographically,
ankylosis gives the appearance
of relative submergence, and the
periodontal ligament space may be
focally absent.3,11,12
The orthodontic
management of ankylosis differs
significantly from that of primary failure
of eruption. Isolated ankylosis responds
well to treatment and may be managed
by extracting the affected tooth
at the appropriate age, or through
luxation and subsequent orthodontic
alignment.3,12
Multiple unerupted teeth
Delayed tooth eruption (DTE) is defined
as the emergence of a tooth into the
oral cavity at a time that deviates
significantly from the norms established
for different races, ethnicities and
gender.11 The mechanisms and
biological underpinnings of tooth
eruption are presently poorly
understood, however, several
rare diseases and syndromes are
associated with delayed tooth
eruption.13
Occasionally, failure of
eruption of multiple teeth cannot
be attributed to a local or systemic
condition. This is a rare occurrence
and the literature contains relatively
few examples of such cases. Their
orthodontic management is varied,
and differing approaches, applied
with varying levels of success, have
been reported.14,15,16
Orthodontic application of
magnets
Many options are available for the
management of unerupted teeth
and these vary in their invasiveness
and ease of application. The least
invasive is the creation of space to
facilitate spontaneous eruption, and
the next line is surgical exposure of
the unerupted tooth with attachment
of a gold chain to allow application
of orthodontic traction. This latter
approach is probably the most
common approach to impacted
teeth, but it does require a surgical
procedure, usually under general
anaesthetic, and the operator must
provide treatment that is relatively
technique sensitive.
Blechman and Smiley
first described the use of magnets to
achieve orthodontic tooth movement,
and since then magnets have been
used successfully in a wide variety
of orthodontic applications.17,18 An
application for impacted teeth was
first described by Sandler et al and
involved the attachment of paralene
coated, rare earth magnets to the
unerupted tooth using composite
resin, followed by provision of a
removable appliance containing a
larger magnet.19 The magnets must
be correctly placed with opposing
poles approximated, and properly
aligned to ensure optimal direction of
pull. Once they are in place, the only
adjustment required is the occasional
repositioning of the magnet
contained within the removable
appliance, until the two magnets are
almost in apposition.
This method requires
little manual dexterity of either the
operator or the patient. The speed
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136 Orthodontics
a
October 2019
a
b
Figure 4. Rare earth magnets embedded in an
upper removable appliance.
Dysmorphic features (Figure
2a, b), such as low set ears, had raised
concerns in the past and she was under
review by a geneticist. However, no
specific diagnosis was made. It had
been noted that she had hypertelorism,
a small mandible, slightly high palate
and hypermobile wrists. There was no
evidence of cranial nerve compression
and fundoscopy was unremarkable.
After seeing a Consultant in
Clinical Genetics, the patient enrolled
into a research study called Deciphering
Developmental Disorders (DDD). The
initial report from that study said ‘No
plausible pathogenic variants currently
identified’.
The orthodontic diagnosis
was made of Class II incisor relationship
on a mild Class II skeletal base with
slight maxillary hypoplasia, and
mandibular retrognathia, increased
MMPA and lower facial height. She
was still in the mixed dentition, with
retained upper Cs and Ds and multiple
unerupted teeth suffering from primary
failure in eruption (Figures 3a–e).
c
b
d
Figure 2. (a, b) Dysmorphic features of
hypertelorism and a small, retropositioned
mandible.
e
of tooth movement appears to be as
quick as other methods, and the slowly
increasing, continuous force may be
more physiological. Palatally directed
forces are more readily applied, helping
to ensure that teeth do not erupt
through the labial plate, and that
they end up with an adequate cuff of
attached gingiva on eruption.
Case report
A 14-year-old female patient presented
with delayed eruption of multiple
teeth. Medically she was fit and well
and presented with a caries-free mixed
dentition and excellent oral hygiene.
Her initial complaint was that she was
extremely anxious about the delayed
eruption of her teeth, and had difficulty
chewing on the left-hand side. There
was no relevant family history and
a genetic aetiology had not been
identified.
Figure 3. (a–e) Intra-oral views from initial
presentation.
Diagnosis
A panoramic radiograph (Figure 1)
revealed the presence of 19 unerupted
permanent teeth. The consultant in
dental radiology reporting the OPT
said that he could understand why
some teeth had not erupted. He
noted that the ‘bone on the left side
of the mandible looked a bit dense’,
however, did not suspect osteopetrosis.
The patient also saw a consultant of
paediatric bone care who noted that
there were no concerns regarding her
skeleton.
Treatment plan
The patient was referred to Chesterfield
Royal Hospital for orthodontic
treatment and a plan was devised to
encourage her unerupted teeth into
occlusion. This included extraction of
remaining deciduous teeth, placement
of an upper removable appliance
containing rare earth magnets, and
bonding of opposite pole magnets
to the upper unerupted teeth to
encourage eruption.
Treatment
Orthodontic treatment was carried out
over a 20-month period. Under general
anaesthetic the remaining deciduous
teeth, upper Ds and Cs, were removed
and Neodymium Iron Boron magnets (3
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138 Orthodontics
a
October 2019
b
upper and lower fixed appliances and
attempted correction of the lateral
open bite on the left with red elastics
to Kobyashi hooks. Sadly, these teeth
proved to be resistant to eruption
(Figures 6a–c). An orthognathic
opinion had been sought during
treatment. It was decided that,
although BSSO advancement would
theoretically be possible, the risks
of surgery were high due to thin
mandible and uncertain quality of
the bone. Lower second and third
molars were also present, removal of
which would be required prior to any
osteotomy.
It was decided that
the treatment had been largely
successful, although it was impossible
to achieve full closure of the lateral
open bite. Despite this, the patient
was completely happy with the
results and declined any further
intervention. She was, however, given
the option of reconsidering further
treatment in the future.
Three years after the end
of treatment, the patient was still
delighted with the result achieved,
was really pleased with her smile and
had no wish for further intervention
(Figures 7a–g).
c
Figure 5. (a, b) Unerupted teeth in a more favourable position for bonding. (c) OPT showing progress
9/12 into treatment.
a
b
c
Figure 6. (a–c) Upper and lower SWA elastics to
attempt open bite closure.
x 3 x 1 mm) were bonded to UL542 and
UR2456. Gold chains were bonded to
the upper left canine, to the lower first
premolars and to the lower left molar,
to aid their eruption by eventually
applying direct traction to the fixed
appliances. An upper removable
appliance was fabricated containing the
larger magnets (5 x 5 x 2 mm) (Figure
4). Magnetic forces were applied for
7 months until the unerupted teeth
were in a position where attachments
could be placed to allow the direct
orthodontic traction (Figure 5a–c).
The case was re-assessed
at this stage with the aid of a CT scan
which showed clear root damage to the
UR2 from the unerupted UR3. It was
therefore decided that the UR2 should
be sacrificed along with the UL3. During
the surgery, the surgeons also removed
a triangle of bone mesial to the LL7 to
aid eruption and exposed the UR7.
A routine course of
orthodontics now followed involving
Conclusions
There is a variety of causes for
unerupted teeth and it is helpful
for all practitioners to be familiar
with the various aetiological factors.
It is certainly helpful if they can
distinguish between primary failure of
eruption and ankylosis.
Many different treatment
approaches have been advocated
for the management of unerupted
teeth. In cases of multiple unerupted
teeth, it is worthwhile considering
using rare earth magnets, as multiple
tooth movements can be carried out
simultaneously to bring the teeth to a
point where they can be bonded with
conventional appliances and aligned.
Compliance with Ethical Standards
Conflict of Interest: The authors
declare that they have no conflict of
interest.
Informed Consent: Informed consent
was obtained from all individual
participants included in the article.
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Orthodontics 139
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