What are the main reasons for implant failure?

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Q: I have been placing and restoring dental implants for about 10 years. There are times when I feel like I placed an implant almost perfectly, but after a short period of proper service, the implant fails. There were other times when I could have done better implant placement, and the implant was successful for many years. There seem to be many reasons for implant failure. What are the most important and common reasons why root-shaped dental implants fail? Can I avoid these situations and expect more predictable service?

A: I feel the same frustration you described. Because of these unpredictable surgical situations, I suggest realistically advising patients considering implants that over 90% of implants serve very well for several years, but some begin to have peri-implantitis or other problems. after about 10 years. Patients need to be educated about potential problems with implants, just as they need to be educated about those associated with natural teeth, and how to potentially prevent problems.

The dental literature is filled with scientific articles suggesting the reasons for implant failure and how to prevent failure. I will summarize some of the reasons sought for implant failure and express my own clinical observations on the failures I have experienced.


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Placing implants in properly diagnosed healthy patients who have adequate bone quantity and quality is a relatively simple procedure that can be accomplished by any dental practitioner who has taken the time to become familiar with the procedure. Similar success can be expected with implant restoration.

Implants should be intended for all patients who need them when all other modes of treatment do not seem adequate. They do not replace a natural tooth on an equal basis and should not be considered as such. However, with proper placement and restoration, implants are an excellent substitute when all clinical conditions are considered.

Every effort should be made to keep natural teeth restorable before removing them and placing implants.

Our organization, Practical Clinical Courses, offers four levels of implant videos and courses, some of which are described below. Our Implant Failure course is one of the most popular courses in our 15 course series.

Rather than include all of the known potential reasons for implant failure, I will limit this discussion to those that I have found to be the most important and common. Additionally, I have not included references for my statements as they are based on countless research projects and my own clinical observations over 30+ years of implant dentistry. Other courses and videos are referenced later in the article.

Occlusion


The occlusion on implants is very different from the occlusion on natural teeth. Inadequate occlusion is one of the main reasons for implant failure. Implants do not move when they are osseointegrated into the bone, whereas natural teeth move significantly into the bone. The implants only have a few microns of movement. Therefore, the occlusion is even more important when it comes to implants than when there are only teeth. Implant occlusion requires careful adjustment at the time of implant restoration and at review appointments. I am convinced that this factor is not currently understood or practiced adequately. The use of thin joint supports (Parkell AccuFilm II), occlusal indicator wax (Kerr Dental Occlusal Indicator Wax) and other concepts are necessary to place a shared occlusal load on the implants and teeth (Figure 1).

Smoking

Try to find any scientific paper that supports smoking (Figure 2). The literature is replete with reports that smoking is a negative factor for the success of dental implants. Although the effect of vaping is not as well studied, there is a growing body of literature showing the negative influence of vaping. Patients must receive adequate informed consent if they are considering implant placement. Dentists are advised to avoid placing implants in patients who will not significantly reduce or stop smoking.

poor bone

Practitioners can easily see the amount of bone by looking at x-rays, especially cone beam images. However, many dentists do not analyze bone quality or even discuss it adequately with patients. X-rays can provide indications of bone density by allowing observation of the size of bony trabeculations.

If the patient is taking bisphosphonates (Boniva, Fosamax, etc.) as instructed when collecting their diagnostic data, ask which practitioner started them on bisphosphonates. Call this practitioner. He or she will usually have performed a T-score test to determine the severity of bone quality. Usually, the patient will be osteopenic or osteoporotic if taking bisphosphonates (Figure 3). It is nearly impossible to significantly increase bone density, although there are a few medications indicated for this use. I suggest considering treating patients who having low bone density with conventional dental treatment rather than playing with potential implant failure.

Loading implants too soon

There has been significant marketing to patients and dentists about “teeth in a day”. Patients and some practitioners see these ads and think it’s still a viable alternative. In some clinical situations, this is an acceptable alternative. However, the clinician performing such treatment must consider all aspects of the clinical situation to determine if perhaps a slower, more predictable alternative would be better for the patient.

What should be considered? Many factors including patient expectations, quantity and quality of bone, long-term expectations for the prosthesis, aesthetics, healing time, ability to predict where soft tissue will heal, obstruction, etc. Often patients have long missing teeth. What is the rush? Slow down and improve procedural predictability and long-term service potential. I’ve had several implant-supported crowns and fixed prostheses that failed due to rush.

There are a few situations where immediate implant placement is superior to waiting for bone maturity. One is in the anterior smile area, where immediate placement of implants can often provide better papilla retention.

Improper implant placement

Wouldn’t it be great if all implant surgery training in dental courses required training in implant prosthodontic treatment planning at the same time? Surgical placement and angulation should be guided by the design of the prosthesis, not the other way around. Unfortunately, it is not the case. Many surgical specialists have not received significant prosthodontic training or experience, and many prosthodontic specialists have not received surgical instruction (Figure 4). Look for courses that simultaneously include surgical and prosthodontic information. Our implant courses described below contain both.

Poor prosthodontic design

The planning and design of crowns and prostheses are directly related to the expected stresses on the implants, esthetics, food impactions, open contacts, soft tissue irritation and potential implant failure. Dentists should be involved in the details of crown and prosthetic design with lab technicians.

Previous periodontal disease

Contrary to previous beliefs, when a patient has had periodontal disease and tooth extraction, the chances of having peri-implantitis later may be increased. In such cases, performing conventional dentistry instead of placing implants or at least having strong informed consent for the patient before placing the implants may be preferable (Figure 5).

Summary

Although root-shaped dental implants have been used for over 30 years and are now popular, in my opinion, we still don’t know more than we know. There are over 20 factors that could cause implant failure. Do we really know what causes the failure of a specific implant? Not often. This article includes the observational and research views of a prosthodontist who has succeeded and failed with implants for over 30 years. These observations include some of the most important causes of implant failure. But there are many other reasons!


Author’s note: The following clinical practice course materials provide additional resources on this topic for you and your staff.

One hour videos:

  • The best implant-supported restorations (article #V2333)
  • Simple occlusal equilibration (item #V3105)
  • Diagnosis and Treatment of Failing Implants (Item #V2391)

Two-day practical courses in Utah:

  • Avoiding Implantation Failures and How to Deal With Them with Jon Suzuki, Kevin Suzuki and Gordon Christensen
  • Implant Surgery – Level 1 or Level 2 with Gordon Christensen

For more information, visit our website at pccdental.com or contact Practical Clinical Courses at (800) 223-6569.


Editor’s note: This article originally appeared in the May 2022 print edition of Dental economy magazine. Dentists in North America can take advantage of a free print subscription. Register here.

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