An Interview with Dr. Michael McCracken
Dr. Bradley Bockhorst: Today, Mike, I'd like to talk about one of the things that is near and dear to your heart: the health effects of edentulism. Why don't you go ahead and tell us a little bit about what you've been doing along that line, both at UAB School of Dentistry and professionally.
Dr. Michael McCracken: Thanks, Brad. It's nice to be here. We have been learning a lot about edentulism in the last 10 years or so. We are realizing how health can be affected by the oral state, and how somebody losing their teeth will lead to all kinds of systemic problems, such as atherosclerosis or cancer. People who have a denture, or who have a poor denture, take a lot more GI medicine. So we are looking at ways that we can treat that as a dental community. I think it's an exciting time to be in dentistry because now we have implants. Now we have options that we didn't have many years ago that we can offer to patients. Instead of telling them they have to have a denture, we can offer them some valuable alternatives.
BB: One of the challenges we face as dentists is that
it's our obligation to communicate to our edentulous
patients what is going on as far as bone loss. Maybe
you can share your thoughts along that line.
MM: I think about that sometimes. We know that one
of the leading lawsuits against dentists is the failure
to diagnose periodontal disease. So a patient goes to
their dentist whom they've gotten along well with for
20 years, and they've been going in every six months
for their checkup. They've been doing what they think
they should be doing on their side. Then one day the
dentist walks in and says: "Well, I'm sorry. You have
periodontal disease. And now you're going to have to
lose these teeth, or you're going to have to have this
surgery, or have these implants placed." Understandingly,
the patient is upset by this and says: "Why didn't
you ever tell me about periodontal disease? Why didn't
you ever tell me I had this disease in my mouth?"
They're upset, and this causes some problems.
Sometimes I wonder: Will we see that with the edentulous
patient? Because now we have a similar situation.
We have a patient who has been going to a dentist
for 20 years. Maybe they come in every year or two
for a checkup or a denture adjustment. And then all
of a sudden they have problems with a mandibular
fracture, or they have a situation where they can no
longer successfully wear a lower denture, or they are
experiencing something else related to bone loss. And
maybe they're going to ask their dentist: "Why didn't
you ever tell me about this bone loss? Why didn't you
ever tell me this was going on? Why didn't you tell me
about this disease?" Because now we can effectively
treat that with implants.
BB: If dentists are not involved with implants, for
whatever reason, do they have an obligation to offer
them as an option to these patients to stop that potential
bone loss?
MM: Absolutely. Clearly, whether you offer those services
in your office, or you refer to a surgeon for implant
placement, the option has to be offered to the
patient. They just need to understand what's going on.
We have some patients who learn the hard way the
effects of bone loss. As an example, we had a lady
who, after being edentulous for many, many years, had
her mandible resorb and resorb, becoming the size of
a pencil. She breaks her mandible as she is walking
out to the pool — stepped too hard, hit her jaw, and
now she has a fracture. It's a very difficult revision
surgery — usually bilateral hip grafts — and quite a
bit of hospital experience. A lot a money and a lot of morbidity come with that when, if somebody had just
told her at the right time that they needed to put some
implants in there to maintain her bone levels, she
would've been much better off. Then it's not a hospital
procedure; it's an in-office procedure — very simple.
Instead of three days in the hospital, you have three
hours in the dental chair.
BB: Are there any studies or any research coming out
of UAB School of Dentistry that are related to being
able to maintain that bone level, or even in some cases
potentially increase it?
MM: Yes. And we did see an increase in bone levels,
surprisingly to me, in a study that was done by the
periodontists at UAB, which was a prospective clinical
trial, long-term, about eight years. And we restored
these patients with five implants in the anterior mandible
and a very traditional Brånemark style, with about
3 mm between the prosthesis and the edentulous
ridge. We noticed over time — this was back in the
nineties — that the tissue would proliferate and touch
the bottom of the bridge. The periodontist thought
we had better clean that up or take that down, so the
patient would have access to clean. When they went in
there to remove that soft tissue, it wasn't soft tissue; it
was bone. So we measured that as part of this clinical
trial, and we saw 1.5 mm, some patients 2 to 3 mm,
of bone gain distal to the implant. So not only are we
maintaining the bone between the implants, we are
actually getting bone maintenance or a bone gain
of up to 2 mm on average behind the implant. So as
we are adding stress back to this system, the bone is
responding by increasing in volume and density.
BB: That leads into one of your other primary interests:
talking to patients about bone loss, and giving them
solutions that are affordable. Maybe you can share
with us a little bit about what you've done at the school
as far as low-cost options for restoring these patients.
MM: Certainly. I do think that is critically important. If
we believe that implants are important, as we do as a
profession, then how can we help more of our patients
get into implants? How can we assist our patients,
let them experience implant dentistry and enjoy those
benefits? At the school, we have developed a lowcost
program that we have offered to our patients.
Of course, keep in mind it's a dental school, and we
have students working on these. But we have provided
the two-implant overdenture, which is just a basic,
entry-level implant prosthesis. We give them the two
implants, the two dentures and the two attachments
for around $1,500. Most people we find can get into
that with a little bit of desire. Most patients are very
satisfied with that price point, and we are able to help
them maintain their bone, get rid of a complete denture
and move into an implant-supported prosthesis.
BB: I believe you're also doing some ongoing work
with 3 mm diameter implants?
MM: We are. To me, this is an interesting potential solution
to some of the costs associated with traditional
implant systems: single-piece overdenture implants.
These are available generally in different sizes, around
3 mm or a little smaller. We wanted to make sure that
this treatment modality was going to be successful
for our patients. We did a clinical trial with about 45
patients, and we randomized those to two, three or
four 3 mm diameter implants in the mandible. I was
really surprised at the results. I'm generally conservative
when it comes to loading protocols, time and so
forth. Obviously, with a one-piece implant, you can't
have delayed loading. So we had immediate loading at
the time of placement, and we had a relatively small-diameter
implant. Clinically, the results were excellent.
I'm gaining much confidence in this treatment
modality.
BB: I know the results haven't been published yet, but
do you have a preference for the number of implants
— two, three, four? Typically when we start getting into
the smaller diameters, they're saying four implants in
the symphysis. What is your take on this?
MM: That was the main question: Do you have to do
four? Because if you're going for a low-cost alternative,
it would be cheaper to do two. And, indeed, we found
no difference between two or four implants, in terms
of implant survival or bone loss around the implants.
So two implants, in our study, worked very well.
BB: Some people call the 3.0 implants "hybrids" because
they are getting close to that conventional diameter,
as opposed to the very narrow implants — the true
small diameters. Would you have a different approach
if you went smaller than a 3.0?
MM: I've still been a little nervous about the smallerdiameter
implants. I just haven't had a lot of clinical
experience with them myself, coming from a more
conventional approach with standard-diameter implants.
But the results that we got from the 3.0 are
encouraging me to try something a little bit more narrow,
because there are times when that's very helpful.
I mean, many patients have a narrow ridge, and you're
faced with the clinical decision of, am I going to remove
6 or 7 mm of bone height so I can get sufficient
width for my implant? Or am I going to simply place a
small-diameter implant? I think maybe we'll be going
more toward the direction of the smaller implants as
we move forward with this.
BB: On the subject of bundling prices to get implant
treatment to an affordable level for patients, you mentioned
bundling two implants, two dentures and two
attachments. Do you have something else if you're going
to do four 3.0? Have you gotten into a bundle for
that, or is that still a work in progress?
MM: For the students, it's still a work in progress. For
my own practice, I think that is very exciting. I love
what Glidewell has done with the package concept
because it really simplifies things for me as a clinician
to know: This is your cost, these are your implants, get
the overdenture for that. Then I can translate that into
a clinical situation with a patient who really wants to
get implants, and who I really want to get into implants.
It simplifies things for everybody. I definitely
plan to pass those cost savings on to the patients.
BB: I understand that outside of the dental school, you
are getting involved in a community clinic. Do you
want to share a little bit of why you got involved with
that and what your plans are with it?
MM: Sure. We set up a community clinic outside of
Birmingham. We're associated with a drug-addiction
recovery program down there, but we're also open for
community patients who don't have much access to
care. And I have to say, it is one of the most rewarding
things I do — even with being a teacher, which is rewarding
in itself. To help people who don't have other
avenues for dental work is extremely exciting. It's a
big volunteer effort from a number of organizations
down there involved with that. But we're planning on
offering them the best dentistry we can, and that's definitely
going to include implants.
BB: That ties right into bundled pricing, where you
can offer services at very affordable prices.
MM: That's right. We have a lot of edentulous folks in
Alabama — sixth highest in the States is our ranking
now, I believe. So we have plenty of people needing
implant overdentures.
BB: Do you know what the percentage is?
MM: For our seniors, age 65 and over, it's more than
30 percent now in Alabama that are edentulous. And
that's fairly consistent with other states.
BB: We've talked a lot about restoring the lower edentulous
ridge. What do you typically do in the maxilla?
MM: The maxilla is a little more of a challenge. The
bone is less dense, of course, and the implants are less
predictable in the maxilla. I've always been an advocate
of multiple implants tied together — be it with a
bar, be it with a fixed prosthesis. But lately I've had
success with individual implants and a cobalt chromium
framework to give structure to the prosthesis, so
that we have some form of cross-arch stabilization and
some splinting from that rigid metal framework. So in
the maxilla, now I'm moving more toward four implants
with attachments using that metal substructure.
BB: If you go that route — four implants and a cast
framework — are you going palate-less, or are you still
doing complete palatal coverage?
MM: I have to say I'm about fifty-fifty on it. Occasionally
I'll take the palate out. I think that's pushing the
limits a little bit. I certainly see that it works in some
patients, but I try to talk the patients into a palate.
BB: Another study coming?
MM: That would be a great study — six implants, no
worries.
BB: Is there anything else exciting going on at the
school or for you personally?
MM: Tough question. I was walking through Glidewell
Laboratories, and I'm really excited about the
milled BioTemps® that are coming out now. They look
beautiful. I've always been thrilled with BioTemps, the
pricing and the esthetics, especially long-term. As a
prosthodontist I have patients' cases for 12, 15 months
waiting for grafting or whatever, and the BioTemps
have held up really well for me. I like the milled
approach they're taking now. It just seems to be a neat
technological advancement.
BB: Yes. Everything is going CAD/CAM. It provides a
more predictable, consistent result.
MM: I think it won't be too long from now when I can
just take a scan of the arch, not even have to make a
cast, and you guys can send me a BioTemps full arch.
BB: Yes, that's coming. Let's step back a minute and
talk about your thoughts on cone-beam scanning,
on using it as a diagnostic tool for those edentulous
patients. Do you do it just for diagnostic purposes? Do
you head toward guided surgery? When would you
use a guide versus doing a flap?
MM: For me, I find that a flap is useful in many of my
surgical approaches. That may be because I need to
manipulate the soft tissue. I may need a grafting in a
certain situation. We may need to thicken the soft tissue.
So, for a variety of reasons, I find that I'm laying a
lot of flaps. For the perfect patient with abundant bone
and abundant keratinized tissue, there's nothing easier
than a guided surgery. With a placement, to have the
confidence and predictability of knowing the anatomy,
you can't beat that, knowing that your implant is going
to come out in the right spot.
BB: At the school, are you guys routinely CT scanning
those patients?
MM: Routinely? No. For me, if the patient has abundant
bone, I don't really need to scan. If the patient
has very inadequate bone, sometimes I don't need to
scan to tell. I know I need to graft. It's the patients
in the middle, certainly large cases, where CBCT is a
great help — especially for the patients where you really
don't know what your approach is going to be. Do
we need to graft? Can we place the implant and graft
simultaneously? Many of these questions are answered
with a cone-beam scan.
BB: We talked about the health effects of edentulism
and keeping patients informed of implants as an option,
particularly implants and prosthetics on top of
them as an affordable option. Do you have any final
thoughts or comments on this?
MM: I think we should be using the fixed prosthesis
more. I see a lot of people who are very comfortable
with the two-implant overdenture, the four-implant
overdenture. I think the fixed prosthesis, a traditional
Brånemark hybrid prosthesis, is one of the best things
we can do for folks, and I'd love it if we were doing a
lot more.
BB: How many implants do you usually like to do for
your hybrids?
MM: Traditionally, I like five, but I'm very comfortable
with four. They can be straight. They don't have to
be tilted. The literature clearly supports four implants
in the anterior mandible. And, just recently, I read an
article that showed good success on three. So maybe
we are even pushing the limit in that direction as well.
But I think four or five implants is very reasonable.
BB: OK, great. So what do they say in 'Bama?
MM: Roll Tide.
BB: There you go.
After completing dental school at the University of North Carolina at Chapel Hill and a prosthodontic residency at University of Alabama at Birmingham, Dr. Michael McCracken received a Ph.D in biomedical engineering for research related to growth factors and healing of implants in compromised hosts. Dr. McCracken is
a professor in the department of general dental sciences at UAB School of Dentistry, where he has also served as associate dean for education, director of graduate prosthodontics, and director of the implant training program. He maintains an active research program within the university and a private practice focused on implant dentistry. He also lectures internationally. Contact him at 
After receiving his dental degree from Washington University School of Dental Medicine, Dr. Bradley Bockhorst served as a Navy Dental Officer. Dr. Bockhorst is director of clinical technologies at Glidewell Laboratories, where he oversees Inclusive
