Understanding peri-implant diseases

Dr. Michael Norton sheds some light on the fierce debate that continues to surround peri-implantitis

Is the current definition of peri-implantitis a good place to start?

It is. It’s also the most difficult place to start, because depending on which body you talk to, it’s defined differently. You could say the simplest definition is an inflammation in and around the area of a dental implant, and just leave it at that.

However, other people go further and describe it by the presence of bone loss, pus, or bleeding. Of course, it may simply be that it’s a scale, and that peri-implantitis is an inflammatory disease, which at its least aggressive, presents with inflammation followed by bleeding, followed by pus, followed by all of those, plus bone loss. Some people define peri-implant mucositis as separate from peri-implantitis, where the former is the inflammatory component and the latter is the infective component, which means the presence of pus. But while peri-implantitis could be strictly defined as inflammation, I think we can say that peri-implantitis is an inflammation with an overlying infection and bone loss.

There was a recent European workshop on periodontology looking into this, with my good friend Professor Tord Berglundh, who is probably one of the names at the forefront of this area. He would argue that peri-implantitis is defined as follows: an implant with 2.5 mm of bone loss; a pocket depth of greater than 6 mm; bleeding on probing; and the presence of pus.

Does the ongoing debate make it difficult to know how widespread the issue is?

I think everyone can agree that if there’s bone loss and pus, then you’ve got peri-implantitis. But when you try to be more precise than that, it influences how you evaluate prevalence. If, for example, you’re somebody who says “all implants that bleed on probing have peri-implantitis,” probably 100% of implants have it. But if you say “only implants with a pocket greater than 6 mm, bleeding on probing, pus, and bone loss,” then the prevalence might go down to 20%, or less.

Interestingly, Berglundh seems to think that the prevalence is quite high, but others have questioned this. In one study published just 4 years ago, prevalence was stated to vary between 11% and 15%, at different levels of severity.

Is it extensive enough that dentists need to start considering it distinct from periodontitis?

Well, periodontitis is a disease of teeth, not of implants — but one of the problems we have is that we try to use indices and markers that establish whether a tooth has gum disease, and relate them to dental implants. For example, if you’ve got a 6-mm pocket around a tooth, there’s no question that that’s disease. It’s not even a matter for debate. But if you have a 6-mm pocket around an implant, it may only denote thick mucosa. It may have no bearing on the disease status of that implant, so there are many healthy implants that will have 6-mm pockets around them.

It’s obviously still a very hot topic; the reason being, of course, that it’s frightening the life out of everyone. If every implant ever placed is going to get peri-implantitis, then the profession has a big problem. I have to say that I don’t think that’s going to be the case at all because I myself have been placing implants for more than 20 years, and while I do see peri-implantitis, it doesn’t dominate my daily practice.

So what are the key risk factors?

I think the ones that most people are agreed on are smoking and a predisposition to periodontal disease, and of course, a lack of oral hygiene motivation. If you’re a patient who has a predisposition to periodontal disease, and you continue smoking, and you don’t clean your implants very well, then probably within 5 years your implants will start to show the early signs — or even the late signs, depending on how susceptible you are — of peri-implant disease. However, there are many smokers in the world who actually don’t get gum disease because they don’t have the predisposition or the genetic susceptibility to it. I would argue that it’s the same with implants for those people, so smoking may not be a risk factor in patients who have a genetic resistance to gum disease.

My personal view is the patient’s genetic susceptibility plays a key role — so a history of periodontal disease is a higher risk factor because it indicates susceptibility. Nonetheless, the vast majority of patients who get implants have lost their teeth by definition, and therefore, the greater proportion of those patients probably had periodontal disease.

So, if all those patients are a high risk for peri-implant disease, why are we not seeing more of it? Obviously, the susceptibility to periodontal disease — even if it is transferable — is not linear. In other words, you may be susceptible to periodontal disease, but that may not make you susceptible to peri-implant disease.

There are so many “howevers” in all this.

Is peri-implantitis a largely preventable condition then?

I don’t think we can say that yet, but I think we are clear that there are ways to reduce the risk. The major bacterial reservoirs in a patient’s mouth need to be removed, which means extracting the most periodontally affected teeth. The patient needs to be put into a regular periodontal maintenance program, and you need a good thickness of peri-implant bone, ideally a minimum of 1 mm or more, around the entire circumference of the implant. If you have these pre-conditions, then I think you can dramatically reduce the risk of peri-implant disease, but you may not eradicate it.

If dentists do come across it in practice, how do they treat it?

There are no formally established treatments. In a broad context though, treatment will involve debridement, decontamination, and then either one of two options.

The first is pocket elimination, which basically means exposing the metal into the mouth. The alternative approach is grafting and repair, which means attempting to re-establish a hard tissue mass around the now decontaminated implant that is exposed outside the envelope of bone.

Pocket elimination is probably the healthier option, but it’s also the most unsightly because patients are left with exposed metal screws visible in their mouth. The inevitable desire is to use guided bone regeneration techniques and try and repair the damage instead. I actually believe that pocket reduction is the less invasive option though, insofar as once you’ve debrided and decontaminated the implant, all you’re then doing is sewing up the soft tissues.

With the graft and repair, you’ve still got a lot more surgery to do. You have to do the bone graft, protect it, and then you have to try and get the soft tissues to go back around the graft and the implant. It’s a much more technically demanding technique.

So how do dentists choose between these approaches?

I think the answer to that is a lot of dentists really don’t know how to handle it. I’m afraid there are a lot of passive treatments being undertaken — non-surgical approaches like mechanical debridement.

These techniques can work over the short-term, but patients who get maintained this way for long periods end up with significantly more bone loss, as these treatments do not always eradicate the disease process. To this end, I set up a center for the treatment of peri-implant disease a few years ago, and we are now regularly getting referrals specifically to treat it.

Does that suggest awareness of the problem is growing?

I think so. It’s interesting that most dentists won’t treat periodontal disease themselves — they’ll refer it. I’m starting to feel that that’s going to happen with implants too.

Part of the problem with treating peri-implant disease is that as the primary provider of those implants, most dentists feel they can’t charge for it. Yet it’s very time consuming, and they may not be availing themselves of the latest technology or knowledge to treat the case.

If they refer the patient, they don’t have to use up their chair time — the patient gets the benefit of going to an expert, and the expert can charge for his/her time because he/she didn’t place the implants in the first place. So, everyone’s a winner.

To enhance this service, I have employed a therapist, Diana Bloom, in my practice, who I’m training up in the non-invasive treatments we have in place. Eventually, it’s my hope that she will be the first recipient of these referrals, and she will make the decisions with me as to whether these patients remain under passive treatment or progress to surgery.

One of the problems we have is that we try to use indices and markers that establish whether a tooth has gum disease, and relate them to dental implants.

Seeing the light

Dr. Norton’s practice is the only European center in an ongoing clinical study to examine the efficacy of lasers in the treatment of peri-implantitis. He explains, “We’re using an Er:YAG laser designed by Morita Corporation specifically for treating peri-implant disease, which shows that people are investing time and money into the problem. The laser not only kills local bacteria but also sterilizes the surface of the implant in the process.” He continues, “We’ve treated about 10 patients so far, and we need 20, so there is still a way to go yet — but if it proves to be effective, I suspect we will be doing a lot more of it.”