I too am interested in this thread -- Richard's comments about the
emplacement or development of secondary dentine are most relevant, and
Idoia should be complimented for having noticed right away that the center
of the pulp cavity appears darker. Secondary dentine is typically darker
than primary dentine.

I'm also impressed with Dr. Tofts' comments, which are based on experience
with live animals. He correctly notes that it would hurt the dog if the
handler simply sawed off the canines. There are a LOT of sensory nerve
endings in the pulp cavities of teeth (as anybody who has ever been to the
dentist knows), and in the absence of injectable drugs which "chemically
restrain" the animal by temporarily paralyzing its muscles (these along
with actual painkillers are what are now used to enable animal dentistry),
one would have to hog-tie the dog.

There is also a considerable blood supply to the pulp of teeth, so that if
the canines were merely sawn off, the tooth would bleed a spouter. To
prevent the dog from actually bleeding to death, which could easily occur,
the handler would then either have to use prolonged pressure (which might
not be effective), or else try to get it stopped by cauterization, i.e.
the application of a hot iron to the teeth.

I have worked for over twenty years with equine dentists, both laymen and
veterinarians, and have been closely involved with all the controversies
over proper practice. An important question in equine practice is whether
a horse's incisors can be reduced (cut shorter) without violating the pulp
cavity. I can attest from years of observation that only an improperly
trained (or untrained) equine dentist ever violates the pulp cavity. The
position of the pulp cavity can easily be verified by XRay, but even where
XRay is unavailable, experience and training on skulls of known age
generally suffice to accurately predict its position. The dentist then
needs to just stay above this level with his cut. In general, the amount
of incisor needing to be reduced for the purpose of re-equilibration of
the bite is less than the amount that is actually available.

In equines, where the teeth are hypsodont and by their nature erupt
continuously through the gums until the part of the crown which is
"reserved" below the gums is expired, for a "safe" cut that does not
provoke an infection and/or periapical abscess, one must merely pay
attention to how high the distal tip of the pulp cavity rises in the
particular tooth. In the teeth of young horses, the distal tip of the pulp
cavity sits higher; but as the horse ages, it retreats by itself due to
what Richard calls "irritation", i.e. by the day-to-day pressures the
tooth experiences in the normal course of chewing normal food. "Retreat"
means the pulp itself shrivels back down toward the tooth root --
essentially shutting off its own circulation to itself, without danger of
dry or wet abscessing. Concomitantly, new dentine (i.e. secondary dentine)
is deposited in the space (the cavity) formerly occupied by the tip of the
pulp. This is a normal process that occurs not only in the teeth of
hypsodont and hypselodont animals, but also in brachydont species such as
dogs and people.

This therefore gives us the answer to all the questions. If someone wants
to shorten their dog's teeth to prevent it biting, he needs only go after
it one part at a time. So that, for example, if the canine above the gum
measures one inch long, the handler probably has at least 1/4 inch that he
can quite safely rasp off of there.

This thins the covering over the pulp chamber, and exposes the pulp not to
infection but to a greater degree of heat/cold and vibrational/pressure
stress, which will induce it to retreat some. The handler can then wait
six months for this to occur and then go after rasping the canines another
eighth-inch or so. This is how attrition in old dogs' teeth works -- all
of us know examples of dog skulls where the animal itself has worn its
teeth right down to a stump. All rasping does is accellerate the process.

It's funny how older cultures were often smarter than we are. Why would we
have to imagine that a man would be so foolish and wasteful as to make his
dog hate him by abruptly cutting off the canines in some cruel manner?
They had more time than we often seem to. My horsemanship teacher, the
great Ray Hunt, used to say "a lot of people know how to get things done
by making war, but only the few know how to get things done by making
peace."

As to Richard's observation that the rim (of enamel) surrounding the
apparently rasped dentine body of the canine tooth is problematic because
it is standing up unrasped -- I think this is like what we see in horse
incisor teeth, where the enamel rim of the anterior surface of the tooth
normally stands up. If the tooth has been experiencing natural wear, it
stands up because enamel is harder than dentine. If the tooth has been
reduced by the equine dentist's rasp or tooth-cutter, it will be smooth on
the day the reduction is performed but within two months the enamel rim
will be standing up again -- for the same reason, that the dentine will
wear down faster than the enamel.

I'm more worried about Idoia's other canine, which appears to be twisted
in the socket 90 degrees, as well as peculiarly worn. Maybe this dog got
into a fight with another dog or another animal, or somehow got his front
teeth hooked in something and halfway pulled that canine out. I've seen
two domestic and one of my Vindolanda dogs with similarly displaced
canines -- either upper or lower -- but all of them have more evidence of
abscessing in the jawbone around the canine alveolus than does Idoia's
specimen. -- Deb Bennett



> That's an excellent macro of the occlusal surface.
>
> Do the other teeth show similar scratches?
>
> I ask this because I don't interpret the scratches on the canine as an
> artefact of filing down.
>
> The scratches are so unidirectional that it is tempting to attribute
> them to filing down. But if they were due to filing down, then how do we
> explain the residual raised perimeter around the scratched area? The
> unscratched curved margin at the base of your photo is a particular
> problem. The scratches terminate within the margin of the occlusal
> surface, whereas a file could surely not leave a margin unscratched. The
> scratches would run to the edge.
>
> I wish I had some alternative explanation, but I can't think of one off
> the top of my head.
>
> As for the exposed pulp cavity, in humans secondary dentine is deposited
> within the pulp cavity in response to irritation caused by attrition of
> the worn crown. There are many cultures that eat abrasive food. The
> abrasion is not caused by the food itself, but by contamination of the
> food with silicious particles such as silt and sand. Sometimes the
> natural process of replenishment of dentine cannot keep up with the rate
> of attrition. So the pulp cavity becomes exposed and apical abscesses
> set in. This process, and its deleterious results, were common in
> traditional Aboriginal Australia.
>
> Presumably this imbalance in replacement of dentine can occur in animals
> too. So I am unsure that the mere exposure of the pulp cavity proves
> that the grinding was rapidly carried out.
>
> Finally, a comment on the photo of the left side of the jaw. Are we
> looking at erosion of bone around the roots of the canine and adjacent
> tooth? It is difficult to tell from a photo alone, but it looks somewhat
> like the results of a chronic apical abscess.
>
> I hope the flow of analysis and speculation continues. This is an
> interesting thread.
>
> Richard Wright
>
>
> On 28/10/2011 01:01, Idoia Grau wrote:
>> I have uploaded another picture of one of the canines, taken with a
>> microscope. The marks that I mentioned are clearly visible here.
>>
>> http://zooarchaeology.ning.com/profile/IdoiaGrau
>>
>
>
>


> That's an excellent macro of the occlusal surface.
>
> Do the other teeth show similar scratches?
>
> I ask this because I don't interpret the scratches on the canine as an
> artefact of filing down.
>
> The scratches are so unidirectional that it is tempting to attribute
> them to filing down. But if they were due to filing down, then how do we
> explain the residual raised perimeter around the scratched area? The
> unscratched curved margin at the base of your photo is a particular
> problem. The scratches terminate within the margin of the occlusal
> surface, whereas a file could surely not leave a margin unscratched. The
> scratches would run to the edge.
>
> I wish I had some alternative explanation, but I can't think of one off
> the top of my head.
>
> As for the exposed pulp cavity, in humans secondary dentine is deposited
> within the pulp cavity in response to irritation caused by attrition of
> the worn crown. There are many cultures that eat abrasive food. The
> abrasion is not caused by the food itself, but by contamination of the
> food with silicious particles such as silt and sand. Sometimes the
> natural process of replenishment of dentine cannot keep up with the rate
> of attrition. So the pulp cavity becomes exposed and apical abscesses
> set in. This process, and its deleterious results, were common in
> traditional Aboriginal Australia.
>
> Presumably this imbalance in replacement of dentine can occur in animals
> too. So I am unsure that the mere exposure of the pulp cavity proves
> that the grinding was rapidly carried out.
>
> Finally, a comment on the photo of the left side of the jaw. Are we
> looking at erosion of bone around the roots of the canine and adjacent
> tooth? It is difficult to tell from a photo alone, but it looks somewhat
> like the results of a chronic apical abscess.
>
> I hope the flow of analysis and speculation continues. This is an
> interesting thread.
>
> Richard Wright
>
>
> On 28/10/2011 01:01, Idoia Grau wrote:
>> I have uploaded another picture of one of the canines, taken with a
>> microscope. The marks that I mentioned are clearly visible here.
>>
>> http://zooarchaeology.ning.com/profile/IdoiaGrau
>>
>
>
>