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JD: You’re a learned man because that’s correct. Fifteen
to 20 percent of the time the dentist misses the mandibular
block and needs to give a secondary one. And then,
well, two things. One, with the Gow-Gates that number
is far less — I’ll say 90 percent of the time to 95 percent
of the time, the Gow-Gates gets it with the first injection.
Another reason, though, that dentists miss the standard
mandibular block technique is they’re uncertain where
to penetrate for the injection, because if they don’t see
that pterygomandibular triangle, all of a sudden they’ve
lost their visual landmark. And if they use that coronoid
notch to determine it, well the coronoid notch is really
too low and the coronoid notch is probably 15 mm lateral
to where they need to be penetrating, so it can be really
difficult. That’s one of the reasons the standard inferior
alveolar is so often used; the dentist doesn’t know what
to do and there aren’t any landmarks.
MD: That’s a good point, and I just thought of that the other
day. A female patient came in, an obese patient in her 50s,
and when she opened wide there was a lot of fatty tissue back
there. There wasn’t a landmark to be seen, and I was really
happy that I was planning on giving her a PDL injection
on tooth #19. It occurred to me for the first time that, wow,
this is a great technique on somebody like this, where I know
I would’ve missed that block the first, second, maybe third
time because there was so much fatty tissue back there. I just
couldn’t see the landmarks we traditionally associate with
a standard lower block. Now on that type of patient, where
you don’t see the landmark, it’s a little different for the Gow-
Gates, right? Are you able to use different landmarks in a
patient like that?
JD: Well, the landmark in the neck of the condyle will
help the dentist and the hygienist who is certified in
local anesthesia know where to aim. But I think the other
determination, whether it’s the standard injection or the
Gow-Gates, is that it’s so important to actually feel the
penetration site. Our first-year students can find the
penetration site with their eyes closed. Of course the
hand has to get to the mouth, and they learn by finding
it on their own. So it’s a tactile type of mandibular
block, where the person will find where the ramus is running
up toward the maxilla. Sometimes the absence of
mandibular molars makes it difficult for a dentist, having
lost the landmarks they’re used to. But instead the dentist
can find where the ramus runs up toward the maxilla
and then find the internal edge and penetrate medial
to that. If there aren’t landmarks, you can feel that internal
edge of the ramus, you can run your finger a little farther
medially and then feel the ligament and go, OK, I’m
just penetrating between these two structures. So, even
when the visual landmarks aren’t there, the tactile ones
always are, and that is really a helpful thing; it’s one of
the things I really enjoyed in the article by Dr. Forbes.
He also went over some of the anatomic features for the
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