The mall dentist turned out to be pretty good! Melissa survived her
root canal just fine, after some initial nervousness. It turns out
that Canada and the United States use different systems to identify
(number) teeth. In fact, it's more complicated than that. In the
U.S., there are two systems in use: the “Universal”, which starts by
numbering the backmost molar on the upper right as 1, and moves left
ending with 16. The bottom teeth are numbered from the backmost molar
on the left (17) through 32. (Kids' “deciduous” teeth are
lettered.) Orthodontists tend to use a different system, which
numbers teeth within quadrants, starting with the front incisors.
In Canada, teeth are numbered with the backmost right molar as 18 and
ending with 28 on the top, and (starting again with the backmost right
molar) on the bottom as 38, counting across to 48.
Neither system is the international standard, which is even more
bizarre and illogical.
In any event, the difference in numbering systems meant that the
estimate they gave me was for the wrong tooth, and was, of course,
low. There also turned out to be four, rather than just three, roots.
I got to watch the whole thing. It turns out that what they do is
drill through the top of the tooth until they reach the pulp. They
then clean out all the pulp, revealing the tops of the roots. They
then use these tiny files to scrape out all of the organic material in
each root, checking the depth against the X-ray, and, finally, with an
electronic device (which I guess works by measuring resistance—one
electrode touches the tongue, another clips onto the files).
Once they've reached the bottom, they clean the roots out with thin
paper spikes, then insert rubber spikes into the openings, dipping
them in gutta percha to fill up any additional gaps and make them
stick in place. When the roots are filled, they burn off the ends
with a tool heated with a miniature torch, then seal them off with a
layer of gutta percha. The rest of the cavity is filled with some
composite material that has to be cured with ultraviolet light, and
the top of the tooth is molded to appear more or less natural.
Because of the amount of the tooth that's been removed, the dentist
recommends a crown, which will protect against the tooth cracking or