The early struggle for
Howard: Most of my podcast listeners are usually under 30, who don’t necessarily know the history of implants and their acceptance in the dental community. When I was in dental school, there was one guy who started to place implants, and the other faculty at the University of Missouri Kansas City called him “The Quack,” “The Butcher.” A lot of states crucified these dentists—sometimes the first time an implant failed, the dentist’s license would be taken away. Those were tough pioneering days.
Carl: The handful of us who were doing implants on a regular basis were put up in front of the board. It’s amazing that we continued through the process.
Dentistry at large was against implant dentistry until the staple implant opened the door … but only oral surgeons could do this extraoral approach, putting the implant through the chin. Also, when the Branemark system came in, it was sold only to the oral surgery community, so of course oral surgeons started saying, “Yeah, implants are a good thing! And by the way, we’re the only ones that can place them.” They used it primarily to promote their practices.
Once the universities got through that system, the periodontists went to Nobel and organized dentistry and said, “We’re a surgical specialty, too; we also should be able to do this.” Most recently, prosthetics has changed its definition—now they’re also doing implant surgery.
Although organized dentistry kept implants out of the private practitioner’s office, it was the private practitioners who developed it; most of the implants that were on the market were designed by private practitioners … but the university-based education would tell graduating dentists to stay away from it.
Howard: One of my friends in Phoenix did a sinus lift in 1987, and an ear, nose and throat specialist saw it later and reported to the board. It was like the Catholic Church back in the Inquisition.
Carl: Flash-forward 30 years, and a hospital across the street had me train all its ENT residents in how to do a sinus graft because it figured this might be a way to treat some chronic conditions of sinusitis. Here we go again—going from saying something is outside the standard of care to teaching all residents how to do the procedure.
You’re not right for every patient
Howard: When dentists go to a conference because they want to start getting into implants and they see 275 different people selling titanium implants, what should they thinking about when they’re trying to invest in an implant system?
Carl: It depends on their training and experience level. Certainly, experienced practitioners could use one system for most everything they do within their own practice. However, they probably shouldn’t treat every patient that comes in the door. When I first got out of dental school I thought if I saw the lecture on it, I’d be able to do it. If one of my early patients got endocarditis, I’d probably admit them and do the flap replacement myself, but as I’ve matured, I’ve realized that there are some cases that, regardless of your training, you should refer to somebody else.
Every surgeon that I’m aware of at every hospital, before they do surgery they have to send the patient to an internist who does a review of the patient in internal medicine and clears them for surgery. Even world-renowned heart transplant surgeons must send their patients to the internist department at the hospitals before they can do their surgery.
A dentist should be aware: It’s not something against you if you get a second opinion, or if you refer a patient for one aspect of care. You don’t have to do everything for the patient if you put the patient first, rather than your ego first.
Dr. Misch enlisted some of the leading clinicians in the field to be educators at the Misch International Implant Institute—including Dr. Randolph R. Resnik, left, whom Dr. Misch chose to carry on the Institute.
Dr. Misch holds a thesis by Indian dentist Dr. Ibrahim Shaikh, who made Dr. Misch the subject of the report
The most important part
of implant treatment
Howard: Do you recommend any particular implant systems, or would you rather remain agnostic?
Carl: The most important thing isn’t the system but the treatment plan. You can have the best system possible, but if you have a stupid treatment plan then it’s not going to work. You should spend more time talking about where the implant should be positioned, how many implants should be used, the quality of bone, the angulation and position at which the implant’s placed, the size of the implant.
If I look at my evolution, the implant design is No. 9 on the list as far as importance now. Much more important are things that people often ignore—patient stress factors, for example. Biomechanical stress is a major reason for complications, so we look at each patient’s particular stresses and conditions.
If you know, for example, that the most common reason this prosthesis has a problem is that the abutment screws get loose, you look at the nine things that contribute to abutment screw loosening and implant diameter is a major one. Platform size is a major one. The torque you put on the screw is a major one. You start looking at where these systems fail. Then you build up a stop against those most common failure systems so you’ll have fewer complications.
I go back to the one implant. One implant has been used. There are some pretty good studies showing that one implant in the symphysis for an overdenture is equivalent to two implants. When I see two implants I’ve got an hour-and-a-half lecture on complications related to the two-implant overdenture. If we look at where the complications are coming from and then the cause of the complications, then you can build treatment plans or concepts that reduce the complications and increase the success rates. It rarely is related to faster, easier, simpler.
Cement versus screws in implants
Howard: A common question with a single implant placed with a single crown is, do you cement that or screw it?
Carl: I’ve got 17 reasons why a cemented crown has an advantage over a screw-retained crown. If multiple implants are being joined together, it’s almost impossible to screw-retain the prostheses and have it passive. The metal/metal connection in implant prosthetics means you can have zero tolerance for error in fabrication of the prostheses.
When you’re splinting things together using a screw, you get variance of fit. A 20-Newton-centimeter force on a screw is enough mechanical force to move two railroad cars if they’re on level ground. Literally when the screws are applied, the implants move in the bone with immediate load of quite a bit of result. It increases crestal bone loss, the risk of early implant failure, and the risk of screw loosening later during prostheses function. A major advantage of multiple implants being splinted together when they’re cement-retained is that you have a cement space; as a consequence, it’s easier to get a passive casting. Cement, in many cases, is a better alternative.
Howard: Do you think there are too many immediate-loaded implants being done today?
Carl: Yeah. It’s a “fashion topic.” To be popular, you need a subject that hasn’t been discussed before. The fashionable color at the present.
The concept that was tried-and-tested was submerged healing, making sure integration was complete, fixing the problem before making the prostheses if any bone loss exists, etc., and going ahead with the prostheses. Immediate-load, compressing all this together, became fashionable because it was different and, because it was faster, you collected your money earlier.
The thing that protected many patients early on in somebody’s early learning curve in surgery is that the fee is so high most patients say no, so they hurt fewer patients. I can’t tell you how many doctors have been through the Misch Institute and said, “God, I wish I had taken this course three years ago. I’ve treated 50 patients the wrong way. I’m seeing these complications.”
For example, the two-implant overdenture. The average postoperative complications are four to six, which take six to 10 postoperative appointments. it’s not cheaper what you’re doing. Every time you see a patient for a postop complication for a two-implant overdenture, you lose $150.
After the sixth time, you do a reline. The second-most common complication is doing a reline because you changed the attachment three times; now you’re doing a reline. You’ve lost the whole profits of the case, and you’ve got the next 40 years that’s this patient’s going to keep bothering you.
Dr. Misch’s son, Carl Jr., has been named the newest CEO of the Misch Institute.
Dr. Misch relaxing in Orlando, Florida, in 2004, after the S3 portion of the Misch International Implant Institute’s 15-Day Surgical series had concluded.
Howard: A frequently asked question on Dentaltown is whether, to rule out complications, dentists should get rid of smokers.
Carl: This is a personal decision within your practice. I did 50 consecutive cases of sinus graft in smokers, and I did not find any difference in the smokers than in the nonsmokers. There was a slightly higher incidence of tearing the mucosa during the procedure, but they did not become infected. All the implants that were placed, which was more than 120, were still there five years later. In that particular study, smoking was not relevant to the particular procedure.
In the United States, though, every periodontist in their literature review reads papers that show smoking is directly parallel to periodontal disease. They have diagnosis of smoking periodontitis and they spend a lot of literature review and discussion on smoking and periodontal disease and alteration of bacteria and the other aspects of it.
To protect yourself medical/legally in the United States, I would tell the patient, “Don’t smoke—it increases your risk of complications and failure, so I don’t want you to smoke.” Then it’s up to your personality whether you’re willing to take the risk. If smokers had a direct correlation to failure, we would have seen it in Europe a long time ago.
However, one of the best residents I ever had was my associate for two or three years before he became my resident. He was one of my best residents—Craig, my brother. He will not work on a patient who smokes. He says, “Carl, I don’t get that many complications, but if I look at the couple of complications I have a year, they’re most always smokers,” so he’s decided that within his practice he’s not going to work on smokers.
It’s like a CAT scan. If you proceed without a CAT scan, it’s not malpractice; it’s not outside the standard of care. But it’s stupid, because you’re going to lose the case if it fails. Same with smoking.
are surgical guides?
Howard: A lot of people say, “You buy my $100,000 CBCT and you can mill out a surgical guide that’s so easy, Stevie Wonder can place this implant. Just snap in the surgical guide and go right through the hole.” But there are other dentists or implantologists who have placed thousands of implants who say they never use a surgical guide. What are your thoughts?
Carl: Did you grow up in the era in which you did not have CT? We would argue whether you should take a panorex. The people who were against taking a panorex would say, “The panorex will show some pathology from the carotid and if you don’t diagnose this, you’ll get sued for it, so don’t take a panorex because it’s showing bigger areas and you’re going to be held to a higher standard because you’re taking a panorex instead of periapical x-ray.”
The new aspect says the same thing about CT. “Don’t take a CT—it opens up a whole wide area of pathology and if you miss to diagnose the cancer in the sinus, you’re held to a higher standard” and that. We’ve seen enough cases. I’ve changed ... as a director of The Institute I’ve seen enough altered anatomies within the CAT scans that are taken with the hundreds of surgeries I review a year that I now say, take a CAT scan. If you don’t, it’s not outside the standard of care but you’re stupid if something happens.
On an early learning curve, don’t skip any steps. Don’t go to immediate load. Don’t go without a CAT scan. Take all the steps and once you’ve got 20, 30, 50 surgeries under your belt, then you make a decision, patient by patient.
Because of our institute’s hands-on courses, we see a few dentists come with a CAT scan and a surgical guide. They put the surgical guide in the patient. They drill the holes through the surgical guide. We reflect the tissue because in these hands-on courses we always reflect the tissue before closing up the case, to make sure there’s bone completely around the implant and that the implant’s in the direction you want, and the implant can be restored.
In more than half the cases when we reflect the facial and the palatal tissue, the implant is out the facial or out the palate. The reason for that is the bur creeps in soft bone. It creeps away from harder bone, so you drill into a ridge and if there’s hard bone on one side of the osteotomy and softer bone on the other side—and often it is not homogeneous—the bur creeps away from the hard bone and creeps toward the softer aspect of bone.
Very few times have I seen somebody who uses a surgical guide not have the implant in the wrong place at least half the time.
Too often in implant surgery if the surgeon sets up the kit, the implant’s going to go in the mouth regardless of what happens during the surgery. The implant’s going too close to an adjacent tooth or it’s going out the facial plate … they keep going. Once the implant’s in the mouth, once it gets threaded, in it’s there. It’s successful.
I chose to play this game at the highest level I know. I chose to take the term “doctor” to the extreme. Not what’s easiest, but what if the world was watching me, what should it look like? I’ve got a saying: Don’t compromise the potential 30-year prostheses for a three-month procedure. The procedure is done. The implant’s in the wrong place. Take it out. Do a socket graft. Come back in three months and next time keep both eyes open.
His go-to cement material—
and why it became his favorite
Howard: What would you recommend for cement?
Carl: The best cement was zinc phosphate. It was the most radiopaque, it was the easiest one to clean and it had the longest working time if you used a cool slab. If you’re looking for a nonretrievable cement, the best one was zinc phosphate.
Its disadvantage is that it has the highest compressive strength. Well, the highest is resin cement, which happens to also be the most popular cement. Resin cement is not radiopaque, it grows anaerobic bacteria like crazy, and it’s hard to clean up. You often have to scratch the surface to clean it, and often you end up leaving some behind because it’s radiolucent so probably the worst cement is the most common one that’s used.
If I want something retrievable—and I call it “soft access” cement, not “temporary,” because it’s the final cement—the ones that have zinc in them are good implant cements. They allow the restoration to be retrievable; they’re radiopaque; bacteria doesn’t grow on them; it’s got a long history of use.
For a single-tooth crown, for example, with temporary cement the crown often comes off, but I start with a temporary cement anyway. If that doesn’t work, I go to polycarboxylate cement.
Carl: That’s a brand name that I use. The only issue with Durelon is that it’s more retentive than temporary cements. I use it for single teeth much more satisfactorily than the temporary cement. It doesn’t come out as often. It’s got a better tensile strength, basically.
The Durelon package insert says not to use it with titanium because it can cause corrosion. For about 30 years Alabama has had a study in which any failed implant gets sent to the dental school and we evaluate the implant with OG analysis and electron microscopy to look for the cause of failure and what’s happened to the metal, things like that. We have never seen corrosion related to titanium with Durelon—never seen it once.
I’ve been using it for 30-some years. I’ve never seen corrosion. What the fear of corrosion is about: It could decrease the pH, especially if you were in an infected implant sulcus. Infection accelerates corrosion, and if you have corrosion of a surface, it can decrease the pH and therefore dissolve the bone in the area. I don’t have any pitting corrosion, crevice corrosion. Some smartass who reads package inserts—which is almost nobody in dentistry—may ask you a question, well, what about corrosion? Tell them Dr. Misch has evaluated it, has never seen anything that’s documenting that indeed there’s a clinical problem associated with this. Durelon is the cement that I’ve used the most often in an implant practice.
Sinus lifts and sinus grafts
Howard: There are so many different sinus lifts being taught and of course sometimes better, faster, easier isn’t the most predictable long-term.
Carl: Let’s start off by calling it a sinus graft—which is what we’ve agreed in the profession to call it. The sinus lift is used for individuals who attempt, through the implant osteotomy, the lifting up the floor of the sinus—the sinus mucosa lifts with it, and they call that a sinus lift.
The sinus graft is where we’ll typically most often come through the lateral wall and put graft material on the floor. What has become very popular is this lift procedure from the crest of the ridge. That technique was developed by Tatum.
Anybody who’s done a few sinus grafts knows that the bigger the access window to the antrum, the easier it is to elevate the mucosa. Stress equals force divided by area. If you have a very small window, there’s higher stress put against the sinus mucosa and you’re more apt to tear it. That’s why I tell the people I train that the lateral access window should be somewhere around 10-by-10mm or 10-by-15. If you’re going through the implant osteotomy to lift the floor of the sinus, the diameter of that hole is about 3mm and is often 10mm deep in the bone. You can’t see to the sinus floor, so you put this instrument in and you bang it and you pray that the floor goes up along with the sinus mucosa. Then you take an X-ray because you put some graft material in there and you see something radiopaque and you say, yeah it’s successful. That’s all BS.
At Temple one of the residents did a sinus lift technique on cadavers and every time, the sinus membrane was torn. If you put graft material into that osteotomy like we used to do amalgam in the old day, you increase the risk that you’ll tear the sinus mucosa. It you tear the sinus mucosa, the implant and/or graft is in the sinus proper. If it’s in the sinus proper, there’s a chance that a bacteria smear layer will get on the implant body because sinuses often get infected. If a smear layer gets on the implant body, the body is not able to get rid of the bacteria. It grows on the implant body. There are no blood vessels that go to the implant body, and that bacteria acts as a nidus for future sinus infections and you can’t fix it. I’ve had to multiple times go in and cut off the end of an implant sitting into the sinus proper to get rid of the bacteria smear layer, to get rid of the chronic sinusitis that the patient was having.
One of the most predictable places to grow bone is the floor of the sinus if you don’t tear the mucosa. It’s very simple to do. It takes less than 10 minutes. it’s very predictable if you come in from the lateral wall and you don’t tear the mucosa. If you come through the crest of the ridge, then it becomes unpredictable.
Howard: What type of bone would you put on that sinus graft through the lateral wall?
Carl: Almost anything works. The only material that in a study was done that did not work was demineralized bone. Another study was done in sinus grafts and it was not predictable, because the bone has no hydroxylapatite crystals left so the bone is broken down rather quickly through a cell medium resorption, and doesn’t maintain the space long enough for new bone to fill the site. The worst material you could use on a socket—or the worst material you can use on the floor of the sinus—is demineralized bone allograft. A better material is mineralized bone, because the hydroxylapatite crystals are still present.
Howard: Would you always prefer harvesting something from the jaw in another area? Back in the ramus or somewhere?
Carl: In theory, you’d think autologous bone would be the best material. In a study done out of LSU they compared different materials, and the material that worked the worst was iliac crest trabecular bone. Autologous bone turns out to be the worst, because it acts very much like demineralized bone—it doesn’t maintain the space long enough for it to work predictably. I wouldn’t use iliac trabecular bone.
As a general rule, I try to treat my patients like I’d like to be treated. I’d rather not have to have part of my hip harvested to do a sinus graft if there’s an easier solution like mineralized bone.
The reality of PRF, and the risks of performing IV sedation yourself
Howard: By the way, that Dentaltown continuing education class you put up a year ago, about socket grafting and clinical assessment of missing teeth—a lot of people are talking about spinning blood. Are you a big spinning blood fan?
Carl: If we’re looking at the effectiveness of platelets to grow bone, if platelets had half the ability to grow bone as what some lecturers say, we wouldn’t have red blood cells in our vessels, we would have bone. That’s true, right?
Howard: That’s hilarious.
Carl: Most surgeries I’ve done in my clinical practice have been with IV sedation. Because I’ve already got a needle in a vein to do the IV sedation, it’s simple for me to draw up some blood and spin it down. If I use the platelets and I choose to use, for example, mineralized bone, it sticks the mineralized bone together and makes it more clinically friendly so it doesn’t get sucked up by the aspirator. I can position it more friendly within a sinus graft, so I use it and I’ve got more than 20 cores with and without it. I can tell you it’s probably the least important factor. A little bit of bone, even if it’s tuberosity, is better than a whole bunch of milliliters of blood.
There are a hundred times more growth factors in cortical bone than in blood. If you scratch some cortical bone in the nasal spine, or the symphysis, or the ramus, and you put some of that cortical bone within your graft, that’s a hundred times better than drawing 50cc of blood and spinning it down.
Howard: You said that when you place an implant, usually the patient is under sedation. A lot of dentists are learning IV sedation because they want to place implants. Do you think that’s a good idea, or do you think they should focus on the implants and have an anesthesiologist come in and do the sedation?
Carl: Oh, Howard, there are very few things that we do in dentistry where one mistake makes you lose your license. One of those is IV sedation that leads to death. I know of three implant dentists who had a patient die during implant surgery. In each case they were doing intravenous sedation, it was an anesthetic death and the doctor lost their license.
Here we go back to the risk that you’re willing to take as a doctor within your private practice: Are you willing to do procedures that, if they fail, the patient will sue? Are you willing to do procedures of which a complication includes death? This is a decision that you personally have to make.
Howard: Do you like to do your own sedation or do you have someone else do it?
Carl: It’s easier for me to do my own because coordinating the schedule with an anesthesiologist is another issue for staff. However, when I’ve done that, if I have a patient that is, let’s say an ASA 3, I’m not as comfortable with this patient as I am with an ASA 1. I’ll have an anesthesiologist come in. It’s nice. They come in. They review the history again and they call the patient up afterward and they make sure the patient’s all right. They stay with the patient afterward and they give them a lot of TLC. It’s like having another staff member for that particular surgery.
Why aren’t these specialties?
Howard: Do you think implantology should be a specialty? How about dental anesthesiology?
Carl: I’m prejudiced on that: I wrote the first specialty application, which was sponsored by the ICOI. I wrote the second specialty application, which was sponsored by the AAID. I was on the head of the committee that wrote the third application. In my personal belief, it makes no sense to me that endo and some other things we have—for example, radiology—are specialties and implantology is not.
If implants were a specialty, we’d have more research money coming into the field. We’d have better clinical studies that would be done because residents would do clinical studies and write papers. I think we should have an implant specialty so that we can have standards of care, more research and documented studies, and patients who are treated by people who do this for a living. For all the other reasons we have these other specialties. In my opinion, implant dentistry is certainly more complex than some other specialties that have been developed.
Asking the right questions
Howard: What are your thoughts on mini-implants?
Carl: As a teacher, I try wherever possible to lean on the science and clinical studies to answer any question. When somebody asks me a question about “What do you think about …” it’s kind of a stab in the gut if that person is somebody who’s is held in high esteem, because what they’re telling me is, “Studies and clinical aspects don’t matter. What do you think?”
When it comes to implant dentistry, though, I hold myself in a little higher regard: I base my answers on clinical studies and science, and include personal experiences along with them.
I’m going to reformat your question: “Have you done any clinical studies on mini-implants? What was involved? What did the science say, and does your observation of 30 years’ experience say?”
The studies: In fact my niece won the periodontal award the year that she graduated from University of Michigan. Her master’s thesis was on the mini-implant. We did a study that involved a pain index of regular-size implant surgeries and the mini-size implant surgeries. We found that the postoperative pain reported by the patients was the same in both cases. At the suture removal, the tissue looked very similar in both cases. Whether the tissue was reflected or whether it wasn’t two weeks later.
We pulled out every article on mini-implants and found many of them to be completely dishonest. They’d refer to a “long-term study” that was actually only 18 months—one wasn’t even a year! The major proponent of this particular mini-implant was a guy who had never placed them. He went on sabbatical for a year, then came back as a mini-implant expert. Maybe instead of religion, a guy talked to him about implant surgery, too, but he had no experience because he wasn’t practicing dentistry that year. How can you come back from a sabbatical and be the No. 1 authority on something that you’ve never done? I just ask myself questions, you know.
I know that if I was going to design an implant that was going to be immediate loaded, I’d want one that would have great fixation and great surface area. I’ve really studied implants—I’ve literally measured the cellular turnover rate of bone cells next to different surface conditions and different implant designs.
We’ve seen a direct correlation to the strength of the bone and to the percentage of bone implant contact to the area of an implant, and to the area of the implant that is under compression rather than tension or shear. For example, if you measure the strength of bone in compression before it breaks and then measure the bone in tension, pulling force rather than compression, it’s 30 percent weaker before it breaks in tension. In shear, it’s 70 percent weaker. This is numbers. You’re doing the study.
Your conclusion is if I’m going to immediate-load an implant, I’d like maximum fixation and maximum surface area. If I look at the general design of an implant, does that mean it would look closer to a screw or look closer to a nail?
Many mini-implants look closer to a nail than a screw. The depth of the thread is very minimum. The number of threads is very minimum. The fixation is very minimum. Every carpenter in the world knows that if you’re going to drill a hole in different types of wood, you’re not going to use the same screw device in balsa wood as you are in oak. A nail works pretty well in oak; you’re just pounding the nail in and you’re putting it in by pure spreading compression against the bone and that nail holds a pretty good picture. You put that same nail in balsa wood or in plaster and you put a picture on it, the picture falls down.
If I look at the mini-implant, I’d look at the design. Not all mini-implants are the same. I’d look for one that has deeper threads. I would look at one that has more threads. I would look at one that’s made of titanium alloy.
We looked at the bending fracture resistance of the implant. The bending fracture resistance of materials in general is pi over four, times the radius to the fourth power. Which means if I have an implant half the diameter, it’s 16 times weaker. We did cyclic loading. We found that these mini-implants would often break after 16,000 loads. You have up to 500 loads a day if you don’t have parafunction on a lower denture in the area because of the four meals you have. If you look at the number of strokes that you have per food and all the rest of it. You’re well above 16,000 within a couple years. You want a material that’s going to take a cyclic load so that it’s not going to break. Many of these things broke.
If I use a two-piece implant that’s regular size, I have the advantage that I have a whole selection of different abutments that I can use. I can cover it up. I can have it exposed. I can use a ball. I can use an angled abutment. I can use a cemented abutment. I can use a screw-retained abutment. I’ve got a whole bunch of options how to restore this thing. I know that the implant is integrated before I make the prostheses. Whereas the mini-implant, you’re putting it in and making the sign of the cross.
Most people stop doing it after they’ve done their first 10 cases. You look at their practice 10 years later, they’re not doing the mini-implant anymore. You do the regular-sized implant, submerged healing, you’re guaranteed it’s integrated before you start the prostheses. You don’t have to worry about the patient’s diet. You don’t have to worry about all the other factors related to it. Can it be done? Obviously. You can do a lot of things in medicine. It doesn’t mean you should.
Support these advertisers included in the February 2017 print edition of Dentaltown magazine.
Click here for an entire list of supporters.