An Apple a Day Won’t
Keep the Dentist Away!
The Reptile Doctor, Dr Shane Simpson, details
an insidious affliction suffered by many captive
dragons.
Let’s face it. Going to the dentist is not on most people’s
list of favourite things to do. It’s hard enough getting
ourselves to the dentist let alone getting our pet’s teeth
checked by a vet. But dental disease is not just confined
to our dog and cat companions. It is actually a common
problem that can affect reptiles….and specifically
dragons.
History.
Dental disease, and specifically a type called periodontal
disease, was first described in dragons at the 1994
Association of Reptilian and Amphibian Veterinarians
conference. In that presentation, the authors discussed the
clinical findings, treatment and management of 39 cases
in an assortment of lizard species at Melbourne Zoo over
a five-year period. Importantly they examined the mouths
of some preserved specimens at the Museum of Victoria
and found none of these animals showed any evidence of
periodontal disease. It was therefore inferred that this was
a syndrome of captivity. The authors also made some
suggestions regarding the potential dietary causes of
periodontal disease in dragons and the dietary changes
that should be considered in order to prevent the develop-
ment of this condition. More than 20 years later, there
appears to have been little change in the captive diets fed
to dragons and as such periodontal disease continues to
be a common problem.
Anatomy and pathogenesis.
The dental anatomy of dragons or agamids, along with
those of chameleons and tuatara, is unique amongst the
lizards. These three groups have a type of tooth structure
called acrodont dentition. Their simple triangular-shaped
teeth are fused to the jaw bones and are not continually
replaced throughout life. As such, damaged teeth are
retained rather than shed. In addition the bone-gum
junction in these species is located several millimetres
away from where the tooth joins the jaw bone. The small
section of bone between where the tooth is fused in to the
jaw and where the gum stops is covered by a thin, dull,
enamel-like layer that repels bacterial invasion. Like
periodontal disease in mammals it appears the primary
cause is bacteria, and so when this layer is damaged bone
is exposed upon which bacteria are able to colonise and
establish themselves. Furthermore, if soft diets are fed to
the lizards, bacterial numbers increase due to the fact
there is a lack of abrasion of the tooth and gingival
surfaces. The bacteria release toxins and incite inflamma-
tion of the gum that if left unchecked can result in bone
infection and worse.
Many different species of bacteria have been isolated
from the infected mouths of
reptiles. Specific samples
taken from those animals
described in 1994 found that
both aerobic and anaerobic
bacteria were present in 15
out of 17 affected animals.
Swabs taken from a small
number of normal lizards at
the same time only demon-
strated aerobic bacterial
growth. This parallels the
development of mammalian
periodontal disease, in
Left: bearded dragon
undergoing dental cleaning.
Right: series of images
depicting grading of
periodontal disease.
All images courtesy
Dr Shane Simpson.