AS veterinary surgeons we are
used to performing a clinical
examination and then making
decisions as to presumptive
diagnoses based on our findings.
The list of possible differential
diagnoses then dictates the options
that we present to clients regarding
possible further investigations and
ultimately to the treatments that
we could provide.
We observe
a degree of gingival
recessional
changes with
inflammation
around some
incisor teeth.
We recommend a COHAT procedure
– a Complete Oral Health Assessment
and Treatment. This examination
confirms the loss of periodontal
attachment. Increased mobility is noted
on examination and ideally radiographs
con rm the loss of periodontal bone
support. The owner is contacted and a decision is made to extract the tooth.
But what if there is nothing to see? I can almost hear the response, “If
there is nothing to see, then there
is nothing to worry about.” Usually
I’d agree – but sometimes “there is nothing to see” means that there is
something absent.
Counting is a much underrated skill
in veterinary practice. Many of us
will have experienced the double-take
when you lift a cat, which was quietly
sitting in its basket, out and onto the
examination table. Only then do you
realise that it is actually an amputee…
On a less extreme level, counting is essential to assess normality in
veterinary dentistry.
“Extras” are fairly easy to spot –
when they are whole teeth. But nature
has a habit of playing games with
veterinary dentists.
The left upper premolar in appears pretty normal but close
examination of the occlusal surface
might alert you to a possible problem
should the tooth need to be extracted.
Only radiographs truly demonstrate the extra root that you would have to
contend with.
Sometimes, however, the extra roots are completely non-identifiable
clinically – but much more obvious
radiographically.
So these are cases where there
is nothing (or at least very little) to
see. Fortunately, nature sometimes
smiles on us poor dentists and gives
us resounding clues as to hidden
problems by producing changes to the
shapes of the crowns. This can result
from fusion of teeth – or incomplete
splitting of teeth during development.
Do these extra roots matter? Well
they certainly do if you are trying to
extract the tooth. We normally rely on splitting the tooth into its separate
rooted components – then extracting
each one individually.
If you simply rely on the textbooks
to tell you how many roots and where
they are, then you will come across
problems in 10% or more of cases.
Should you be extracting the teeth due
to infection, then the retained root is
likely to act as a continuing repository
of bacteria and inflammation. This
may cause a continuing discharge from
the area and pain – an unhappy pet and
a dissatisfied client.
Having considered extra teeth and
extra roots, we now have to think
about the situation when our counting
comes up with less than the expected
number of teeth.
This may be due to previous
extractions; hopefully these will be
meticulously documented so that it is
clear from the records that the tooth
was completely extracted 18 months
ago, in which case things are clear.
Especially common in felines are
the “missing teeth” that have not been
recorded as being extracted. These
are frequently as a result of tooth
resorptive (TR) lesions.
Figures 10 and 11 show the left mandible of a cat. The clinical photo
shows an obvious TR lesion to the last
molar (red arrows) – then extent of
the destruction can also be seen on the
radiograph.
However, 307 (turquoise arrow) is
apparently missing – simply a slight
bulge to the gingiva; but the radiograph
shows resorbing roots. Technically this
is a Stage 5 lesion. Another example
(this time a feline canine tooth) is
shown in Figure 12.
As the gums are quiescent and there
are no radiographic signs of apical
infection or endodontic disease, it is
safe to simply monitor these teeth as
they continue to resorb.
The next case (Figures 13 and 14) is
one of true oligodontia – or fewer than
normal teeth.
These missing premolars have simply
failed to develop. Often the temporary deciduous tooth is in place but the
permanent replacement fails to appear.
This causes no significant problems;
however, it is an hereditary condition
and will be picked up by alert judges
(especially in the USA). Ideally, affected
animals should not be bred from.
In Figure 15 the dog demonstrated
a missing canine tooth – this had
never been extracted or had erupted.
He was also suffering from an enamel
hypoplasia, a defect in the development
of the enamel. However, the question
is: where is the right lower canine?
The combined radiographs make it much easier to appreciate
that a distorted canine tooth is actually trapped in the mandible. The incident
that caused this may well have been
responsible for the damage to the
developing incisor enamel as well.
Although these cases are a technical
challenge and fun to deal with
surgically, sometimes our counting
simply reveals teeth that are genuinely
missing.
Another interesting group of
“missing teeth” patients suffer
from dentigerous cysts. These
cysts are usually associated with an unerupted, often abnormal, tooth. The
pathogenesis is uncertain; trauma may
be involved – however, the relatively
high prevalence in Boxers and some
other brachycephalics could well
indicate a genetic link.
They are not uncommon – when
you start to look for them. A cystic
structure develops from proliferation
of remnants of the developmental
enamel organ or the reduced tissue
epithelium.
Initially (apart from the missing
tooth) they are asymptomatic,
but as the cyst enlarges it can lead
to destruction of the local bone,
sometimes displacing adjacent
teeth (which may also suffer root
resorption).
The cyst can become visible under
the gingiva as a fluid-filled structure,
which occasionally may rupture and
become infected.
The lesions are often bilateral
(although sometimes to different
degrees of development).
The cyst expansion can compromise
blood supplies to other teeth –
resulting in pulpal damage.
The goal of treatment is to remove
any severely compromised teeth, or
perform suitable endodontic therapy
if appropriate. It is also essential,
however, to completely remove the
epithelial lining of the cyst wall –
otherwise recurrence is likely. More severe cases can require more complex surgery and
may even result in pathologic fractures
of the jaw.
Conclusion
Don’t forget to count the teeth when
you are examining your patients.
