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2 mm
1.5 mm
1.5 mm
others were looking at the implant
from the shoulder down, and we all
wanted to know how much bone
loss took place after you connected
the abutment and took it on and off
a few times. Dr. Joachim Hermann,
Dr. Ingemar Abrahamsson and others
did great studies on this. And they
were all looking at different implants,
but they were looking at the vertical
bone loss from where the implantabutment
interface was. This usually
went down to the first thread of these
older implants. Now there’s nothing
magical about the first thread; it’s just
that there’s a 1.5 mm distance. That’s
the biologic width reformation. On the
Brånemark implant, that happened
to be where the first thread was, so
everybody thought it was magical, but
it was pure coincidence.
What we weren’t paying attention to
was something I noticed with my patient
Anne-Marie. When I looked at the
case, I realized I had lost the bone between
the two implants because they
were too close. That’s what it looked
like to me. So I went back, because I
couldn’t get the papilla to grow back.
In fact, on that case I eventually had to
submerge a perfectly healthy implant.
I just published this case recently in
Clinical Advances in Periodontics with
Dr. Paul Fletcher, one of my partners.
And I realized, when I went back to
look at the research, what we were
missing: Everybody was looking at
how much bone loss we had vertically,
but there is a horizontal component to
that bone loss. By having a horizontal
component to bone loss, the question
became how deep was it? That article
with Cho and Wallace was the first to
measure that. It was 1.4 mm on that
typical Brånemark-style implant —
1.4 mm horizontally. If you lose bone
not just vertically down the side but
also horizontally, the biologic width
is three-dimensional. The inflammation
and irritation from the abutment
connection moves the bone away from
it vertically and also horizontally. So
what happens is, if two implants are
3 mm apart, each of them are separate
horizontal components and the
bone peak is not affected. But if two
implants are closer than 3 mm, they’re
going to overlap, and so the 1.5 mm
from one implant and the 1.5 mm
from the other implant overlap and the
bone crest will go down; therefore, the
support for the papilla will be missing.
I thought that was the answer, that I’d
solved the world’s problem. So I told
everybody, “Keep the implants 3 mm
apart, and the bone will be higher and
the papilla will come back.” So I figured
that was the problem. And it still
is a problem; 13 years later it’s still one
of the things you need to pay attention
to. But I wrote that and everybody
went and did that, yet in many cases
the papilla still didn’t come back. So
it wasn’t just that horizontal distance.
Even though the peak of bone wasn’t
being lost, the papilla still didn’t come
back fully. What else was I missing,
along with the rest of the world?
The article written in 2003 4 was really
the pivotal one that finally helped
explain it. I went to five different offices
— Drs. David Garber and Henry
Salama in Atlanta, our office in New
York City, Drs. Stuart Froum, Ann
Magna and Paul Fletcher — and what
we found was the same. We all came
up with the same curve. What was
the height of the tissue between any
two implants? What was the peak of
tissue? Not to the contact point, because
those are two artificial crowns
and it could be any shape. But I asked,
“How much tissue forms over the crest
of bone between any two implants?
What’s the average height?” And we
found the average height was 3.4 mm,
not 5 mm and 6 mm as it is between
two teeth. And that’s when it hit me.
We almost never got to 5 mm between
any two implants, no matter what
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