A N KY LO S I S BY GREGGORY KINZER, D.D.S., M.S.D.
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CONTENTS
A L L C O N T E N T S © 2 0 2 0 S P E A R E D U C AT I O N
A N KY LOS I S
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Part I: Etiology and Considerations
6
Part II: Treating Adults With an Ankylosed Tooth
10
Part III: Treating Children With Ankylosed Permanent Teeth
14
Part IV: The Use of Decoronation
18
Part V: Autotransplantation
PA R T I : ET I O LO GY A N D CO N S The ankylosis of a tooth is defined as an anatomical fusion of alveolar bone with cementum and can occur any time during eruption, either before or after the tooth erupts into the oral cavity. Essentially, the periodontal ligament is obliterated by a ‘bony bridge’ and the root becomes fused to the alveolar bone. An ankylosed tooth can be diagnosed multiple ways: • A lack of mobility or a sharp, solid sound upon percussion with a hand instrument (typically only reliable when at least 20 percent of the root is affected) • The incisal or occlusal edge is below the incisal/occlusal plane • The gingival margin or, more accurately, the CEJ is at a more apical position compared to the adjacent teeth • Radiographic examination reveals obliteration of the periodontal ligament space
Figure 1
A N KY LOS I S
S I D E R AT I O N S SO WHAT IS THE
By far, the most common theory
CONCERN WITH
traumatic injury of the periodontal
that is known to cause ankylosis is
ANKYLOSED TEETH?
ligament (Kracke: 1975, Henderson:
The first concern is that the
ankylosis is highest for teeth with
ankylosed root is continually
subluxation or avulsion injuries
resorbed and replaced with bone,
because of the nature and severity of
thereby diminishing the support
damage to the periodontal ligament.
1979, Andreasen: 1981). Risk of
of the crown of the tooth – although
Deciduous teeth become ankylosed
the rate of the resorption may be
far more frequently than do
extremely variable.
permanent teeth, the ratio being
The second is the impact on
greater than 10-to-1, and lower teeth
normal alveolar development if an
are ankylosed more than twice as
ankylosed tooth is present while
often as upper teeth.
the patient is undergoing growth.
Although the initial treatment
The ankylosed tooth will appear as
thought when an ankylosed tooth is
if it is becoming submerged as the
encountered is often to immediately
adjacent teeth erupt.
extract the ankylosed tooth, the
Several theories have been proposed
actual treatment decision should be
on the different etiologies that may
made only after evaluating multiple
cause ankylosis:
different factors:
• A disruption of local metabolism
• Whether the ankylosed tooth
of the PDL (Biederman: 1962)
is deciduous or permanent
• Genetics (Kural, Magnusson: 1984)
• The time/age of the onset of ankyloses
• Deciduous teeth without a permanent successor
• The time/age at diagnosis;
(Brearly, McKibben: 1972)
patient gender • The location of the affected tooth • The smile line In the subsequent posts, I will look deeper into the different treatment recommendations and options given the variety of clinical findings that may be present.
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PA R T I I : T R E AT I N G A D U A N A N KY LOS E D TO OT H Several factors need to be taken into consideration when deciding on the appropriate treatment option for an ankylosed tooth. These factors include: • Whether the ankylosed tooth is deciduous or permanent; • The time/age of the onset of ankylosis • The time/age at diagnosis • Patient gender • The location of the affected tooth • The patient’s smile line. It is known that the root of the ankylosed tooth will typically undergo continual resorption and subsequent replacement with bone. In addition, depending on when the tooth ankylosed, a hard/soft tissue defect in the area of the ankylosed tooth will be present if the tooth became ankylosed prior to the completion of growth and development. If, however, the tooth became ankylosed after growth was complete, there may be no impact on the hard and soft tissue positions. This patient is in her late 50s and has tooth #9 ankylosed. Given the position of the gingival margin and incisal edge of this tooth compared to other teeth in the arch, it is apparent that it became an ankylosed tooth at some time prior to the completion of growth. (Figure 1)
Figure 1
A N KY LOS I S
U LT S W I T H H In contrast, this patient in his
If the treatment chosen is to keep the
mid-30s also has tooth #9 ankylosed,
ankylosed tooth, many options exist:
but the gingival margin is level with
• Keep the tooth and restore in its
the adjacent central incisor, leading
current position;
us to conclude that it became an
• Subluxate the tooth and
ankylosed tooth after growth was
orthodontically reposition into
completed. (Figure 2)
the desired location; • Move the ankylosed tooth into the correct position using a segmental osteotomy containing the ankylosed tooth. If the patient has a low smile line – or the gingival margin position is still correct – and the rate of resorption
Figure 2
is slow, keeping and restoring the ankylosed tooth in its current
When treatment planning an
position is a simple way to improve
ankylosed tooth in an adult, it must
the esthetics. The unknown of this
be stated that the ankylosed tooth
treatment option, though, is how long
does not need to be extracted just
with the tooth will last before the
because it is ankylosed. If you think
resorption advances to the point that
about it, an ankylosed tooth is not
the tooth structurally needs to be
that dissimilar from an osseointegrated
extracted. Even though there is a
implant. The treatment decision
significant gingival margin discrepancy
on whether to keep the ankylosed
on the ankylosed tooth #9, the impact
tooth – and possibly restore it – or
on the overall esthetics is low because
remove it, will depend on the esthetic
of the patient’s low smile. (Figure 3)
impact of any hard/soft tissue defect and the rate at which the resorption is occurring.
Figure 3
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Given that the resorption is occurring at
If the ankylosed tooth is an esthetic
slow rate – the tooth became ankylosed
issue and the rate of the resorption is
prior to the completion of growth and
advancing quickly, extraction of the
the patient is now in her late-50s – the
tooth is recommended. The area will
treatment plan was just to restore the
typically require augmentation with
incisal edges of #8, #9 and #10 with
either hard or soft tissue depending if
composite. The composite restorations
the final restoration is a single tooth
were in place approximately 10 years
implant or a tooth supported FPD.
before the resorption advanced to the
(Figures 5-6)
point that #9 required extraction. (Figure 4)
Figure 4
Figure 5
Figure 6
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PA R T I I I : T R E AT I N G C W I T H A N KY LOS E D P E As was mentioned in Ankylosis Part I and Part II, several factors need to be taken into consideration when deciding on the appropriate treatment option for an ankylosed tooth. When ankylosis is diagnosed in a child, these factors are even more important to evaluate prior to making the treatment decision. These factors include: • Whether the ankylosed tooth is deciduous or permanent • The time/age of the onset of ankylosis • The time/age at diagnosis • Patient gender • The location of the affected tooth • The patient’s smile line Here we have a female patient that presented to the office at the age of 15 with tooth #8 ankylosed. (Figure 1)
Figure 1 This tooth was avulsed when she was 11 years old and re-implanted after being out of the mouth for approximately one hour. The desire of the patient and her family was to improve the esthetics. As you can see, the incisal edge and gingival margin are more apically positioned compared to the adjacent teeth.
A N KY LOS I S
CHILDREN ERMANENT TEETH THE ANKYLOSIS PATIENT
TREATMENT OPTIONS
• The tooth most likely ankylosed at
AND CONCERNS FOR THE
age 11 to 12
ANKYLOSED TOOTH
• The patient is now 15
The treatment options are:
• The patient is female
• Extract the tooth and prepare
Prior to figuring out what we should do,
for implant placement
there are still a few questions that we
• Subluxate the tooth and
need to address:
orthodontically reposition
• How fast is the resorption occurring?
• Use a segmental osteotomy to
As can be seen from the radiographs
orthodontically reposition to the
that the patient brought, the rate of resorption seems to be progressing
desired area
very slowly. (Figure 2)
• Leave the tooth in its current
• Where is the smile line? The patient
position and restore the esthetics
has a very low smile line and does
If the tooth is extracted, she will need
not show the FGM. (Figure 3)
hard tissue augmentation, will have to
• Where is she in relationship to her
wait until she is 17-years-old to have an implant placed, and we will need to
growth? Females generally are done
provide an interim tooth replacement
growing at the age of 17. Given that
option throughout this time period.
she is 15 years of age now, it is
The downside of this option, as far as
anticipated that she is near the end
the ankylosis patient and her family
of her growth phase.
are concerned, is that this is a very formidable time in her life. Managing appointments, schedules and interim tooth replacement would be difficult.
Figure 2 Figure 3
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Subluxating the tooth and
Although the tooth could be extracted
orthodontically repositioning it into
now in preparation for a single tooth
the desired position will have limited
implant, the decision was made to
success depending on how much of
leave the tooth and restore the incisal
the tooth is ankylosed. This option
edge length with composite. (Figure 4)
typically works better on teeth that only have partial or spot ankylosis. Using a segmental osteotomy to reposition the desired tooth can be successful depending on the surgical approach, but could be very problematic if necrosis of the segment were to occur. What about leaving the ankylosed
Figure 4
tooth for now and improving the esthetics by adding to the incisal
The ankylosis patient and her
edge? Will this create more problems?
family knew that the composite was
What we already know is:
an interim restoration and that the
• The replacement resorption is occurring slowly (so it could possibly be maintained for another 5-10 years) • The patient is 15 and near the end of her growth phase (so the defect created by the ankylosis shouldn’t
tooth would require extraction and implant placement in the future. The question of when depends on the rate that the resorption progresses. In this patient, the tooth lasted another 10 years before it required extraction. (Figure 5)
appreciably increase) • The patient has a low smile (so you don’t see the gingival margin discrepancy)
Figure 5
A N KY LOS I S
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PA R T I V : T H E U S E O F D E C O R O N AT I O N Typically when managing ankylosis in permanent teeth in children, it is advisable to remove the ankylosed tooth prior to significant growth so that the subsequent eruption of the natural teeth during growth doesn’t create a significant hard and soft tissue defect. However, as surgeons know all to well, trying to extract ankylosed teeth can be a difficult undertaking. In this example, we have an 11-year-old male who received trauma to the maxillary anterior when he was 10 years old and subsequently had ankylosis of tooth #8. (Figure 1)
Figure 1 As can be seen radiographically, the root resorption is occurring at a significant rate given that the trauma only occurred approximately one year ago. At this time though, there hasn’t been much change in the incisal edge or FGM positions. With this in mind, the tooth can be monitored. The parents are informed that continued recalls are imperative so that the tooth can be extracted prior to formation of a significant hard and soft tissue defect. This must be stressed to the parents because if the patient gets lost in the system or doesn’t return for recalls the defect will become greatly amplified and the treatment needed to correct it will be more difficult. At the age of 12, a change in the incisal edge position and FGM location can be seen. (Figure 2)
Figure 2
A N KY LOS I S
DECORONATION AS A SOLUTION It was at this time that it was decided to
This will allow for the periosteum to
remove the ankylosed tooth prior to the
grow over the remaining root creating
continuation of growth. Mamlgren et al.
a periosteal sling between the adjacent
described a technique in a 2006 paper
teeth over the edentulous ridge and
that discussed the use of decoronation
underlying root. The creation of the
in circumstances such as this. (Figure
periosteal sling will allow some vertical
3) Rather than remove all of the tooth
ridge development in the edentulous
fragments, decoronation removes the
site due to the tension created by the
crown of the tooth approximately 1mm
eruption of the adjacent teeth, while
below the osseous crest. (Figure 4)
the remaining root continues to undergo replacement resorption. (Figure 5)
Figure 3
Figure 4
Figure 5
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This decoronation technique has been
If decoronation is considered in the
modified to include hollowing out the
growing patient, the key is that provide
internal of the root in addition to
the treatment prior to the patient
cutting off the coronal portion below
undergoing significant growth.
the osseous crest. The benefit of this is that the resorption will occur at a more rapid rate as it will be occurring from the internal as well as the external aspect of the root. The difficulty in managing these patients with extraction of the ankylosed tooth is providing interim tooth replacement until the cessation of growth (this is especially true in males where growth may not be completed until 21-22 years of age). As can be seen though, when the patient is ready to undergo implant treatment, the ridge height is relatively good, making the management of the ridge more predictable for an implant or a pontic. (Figure 6)
Figure 6
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PA R T V : A U T O T R A N S P L A N TAT Typically when managing ankylosed teeth in children it is advisable to remove the ankylosed tooth prior to significant growth cycles so growth and subsequent eruption of teeth don’t create significant hard and soft tissue defects. However, the difficulty in managing these patients is providing interim tooth replacement until the cessation of growth. This is especially true in males when trauma occurs early in life (ie. age 9 to 11) and where growth may not be completed until 21 to 22 years of age. This can be a considerable amount of time to manage the edentulous ridge and provide an interim restoration that doesn’t significantly impact them socially. The main image shows a 10-year-old male patient with an ankylosed tooth #9 that is beginning to show signs of incisal edge and gingival margin asymmetry.
Figure 1
A N KY LOS I S
TION ANKLYOSIS AND
THE REQUIREMENTS
AUTOTRANSPLANTATION
NEEDED FOR
One option that I have previously
AUTOTRANSPLANTATION?
written about is the use of
The harvested tooth needs to have a
autotransplantation to manage these
root length that is two-thirds to fully
young patients. Autotransplantion is
developed and have an open apex.
a procedure that utilizes the patient’s
This will provide the most predictable
own teeth, typically the mandibular
transplant for retaining vitality as
second premolar, as a replacement
well as having continued root
for missing anterior teeth by extraction
development. Generally, the patient
and re-implantation. The transplanted
that has a mandibular second premolar
tooth can then serve as an esthetic
that meets these criteria is typically
and functional replacement for the
between the ages of 10-12. (Figure 2)
patient. The major concern for most dentists is: how predictable is this type of treatment? A 2002 paper from the Am J Orthod Dentofacial Orthop (Czochrowska EM, et al.) entitled Outcome of Tooth Transplanation: Survival and Success
Figure 2
Rates 17-41 Years Post-treatment showed a 90% survival rate (with a mean observation time of 26 years). By comparison with other treatment options, this is an extremely favorable outcome. However, it must be stated that the success rates is highly dependent on the skill and experience of the surgeon performing transplantations. I have been fortunate to work with Dr. Jim Janakievski in Tacoma, WA whom I consider to be one of the world experts in the area.
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Hence, this treatment option has a narrow window of time where it is viable. The transplanted teeth placed in a similar position of eruption as they were in when harvested. (Figure 3) These teeth typically have continued root development and even maintain their vitality which can be attributed to their stage of root development at
Figure 3
the time of harvest. The transplant tooth can be built up with composite and the patient can continue on with orthodontic treatment. (Figures 4 and 5) Although this is not a treatment option that needs to be utilized every day, it is wonderful to know
Figure 4
that autotransplantion can provide a predictable esthetic and functional replacement for these patients that would otherwise have to wait 10 to 12 years, until the completion of growth, before the implant can be placed.
Figure 5
ABOUT THE
AUTHOR A gifted academician and clinician, Dr. Kinzer’s interdisciplinary approach to dentistry is founded in empirical research and clinical experience. His unique ability to impart complex clinical processes in a logical, systematic and understandable way differentiates him from other dental educators of our time. Committed to advancing the art and science of restorative dentistry, Dr. Kinzer continues to serve as an affiliate assistant professor in the graduate prosthodontic program at the University of Washington School of Dentistry. He also taught with Dr. Frank Spear at the Seattle Institute for Advanced Dental Education from 1998-2009 prior to joining Spear Resident Faculty. In addition, Dr. Kinzer has written numerous articles and chapters for many dental publications and serves on the editorial review board for the Journal of Esthetics and Restorative Dentistry. He maintains a private practice in Seattle limited to comprehensive restorative and esthetic dentistry. Dr. Kinzer received his D.D.S. from the University of Washington in 1995 and an M.S.D. and certificate in prosthodontics in 1998.
Greggory Kinzer, D.D.S., M.S.D.
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