Q: Do ferrets chewing bone have stronger jaw bones than those eating
   kibble?
 
A: Now THAT is an interesting question!  I wish I could answer the
question in a definitive manner, but, frankly, I am not sure and I don't
think ANYONE knows the answer.  The problem is not that I can't show pet
ferrets have smaller maxillas and mandibles (jawbones) than polecats or
feral ferrets; they do, but the problem of neutering makes the data hard
to interpret correctly.  Toss in the ferret's sexual dimorphism (males
are larger), and you now have a morphometrics mess.  And that doesn't
EVEN address the issue of how dietary nutrients, maternal effect, the
jill's diet during pregnancy, the kit's diet during growth and
development, disease, and genetics complicate the issue!  I CAN say a
scale from "Most Robust" to "Most Fragile", wild male polecats/feral
ferrets eating a natural diet would be at the massive end, while early
neutered pet female ferrets on a kibble diet would be at the petite end.
 
Ferret teeth are fastened in the jaw in four ways: the tooth roots,
dental cement, the periodontal ligament, and the bone surrounding the
socket (alveolar bone).  In ferrets, roots are generally simple and
tapered, and most teeth will readily fall out of a cleaned skull (it also
makes them easy to pull).  The upper and lower carnassial teeth (cutting
teeth) and the upper molar have roots set at a slightly obtuse angle,
helping to hold them in their sockets (alveolus), and these teeth are
generally the only ones left in fossil polecat skulls.  Dental cement is
seasonally deposited on the root from the edge of the crown to the
apex (the tip of the root), forming a firm surface for attaching the
periodontal ligament.  The periodontal ligament is a tough, rubbery
connective tissue that bridges the gap between the root and the bone
making up the tooth socket (alveolar bone).  This ligament is what holds
the tooth to the bone, yet allows some give and take while eating (if you
hold one of your front teeth and wiggle it, you can feel the pressure on
the periodontal ligament in your socket, and the wiggle is the "give and
take").  Without the cushioned give and take, both the tooth and the
supporting bone would be so physically stressed during chewing that they
would fracture, crush, or fragment, and the tooth would be rapidly lost.
The bone surrounding the tooth socket (the socket is the hole, not the
bone) is plastic, responding to biomechanical stresses, tooth eruption,
loss, etc.  by increasing or decreasing the amount deposited around the
tooth.
 
When a ferret loses a tooth, not only is the socket ultimately filled in
with bone, but the thickness of the mandible is also reduced at that
point.  The reason is because the bone responds to biomechanical pressure
(like ALL bone), beefing it up to make sure it doesn't give under use.
If a single tooth is lost, the reduction of the mandible rarely endangers
the jaw, but if several adjacent teeth are lost, the bone mass lost could
increase the risk of fracture.  There ARE some evolutionary odontologists
(tooth scientists) that have recently been presenting data suggesting
dental health is enhanced by adherence to an evolutionary diet, including
chewing periods similar to those found in wild members of the species.
 
Prolonged chewing, such as when a ferret gnaws on the ends of a bone,
"wiggles' teeth within their sockets, stressing the periodontal ligament,
and stimulating bone production (or turnover).  Minimally, this helps
maintain healthy bone surrounding the socket, and it probably causes
additional bone to be laid down.  However, I know of no published studies
that would support such events in ferrets.  Also, I suspect even if the
phenomenon were true, the changes caused by neutering could be more
pronounced, neutralizing whatever gain in bone mass potentially imparted
by prolonged chewing (this MAY actually be an argument FOR prolonged
chewing, if you think about it...).
 
Thanks for the excellent question; you've given me something to think
about.
 
Bob C
[Posted in FML issue 4173]