What Causes Dental Implant Failure?
Dental implant failure is a rare occurrence. In fact, about 95 out of every 100 implants integrate successfully. This type of dental prosthetic can last for many decades with no maintenance beyond normal brushing and flossing. However, some failures do occur. This can happen early on, during the osseointegration stage when the bone is healing. This is called “rejection” of the implant. Other types of failure may show up many years after the fact when the prosthetic breaks or disease damages the surrounding tissue. Here’s a look at some of the factors that can increase the risk of things going wrong.
Dental Implant Failure Due to Oral Health Problems
Poor bone density resulting from periodontitis (gum disease) is a common cause of implant failure. This is a significant problem in patients who have been missing a tooth for a long time. The longer a socket is left empty, the more bone volume and density decreases. This resorption of bony tissue occurs because the body is not receiving any signals that there is a live tooth there that needs support. The blood supply to the area is usually impaired as well. Finally, the bacteria and tartar buildup that lead to periodontitis in the first place can cause inflammation in the oral tissues.
All of these problems make successful implant placement difficult and may lead to early failure. Getting gum disease under control prior to implant surgery is essential. Bone grafting may need to be done to reestablish sufficient bone presence. A blade implant that requires less bone volume and density (as determined by a CT scan) is often the best type of prosthesis to use for patients in this situation to reduce the risk of dental implant failure.
A periapical lesion that forms because of a dental abscess around a tooth root can interfere with a dental implant in an adjacent tooth socket. The lesion causes ongoing inflammation that contributes to the failure of osseointegration. The lesion must be treated and resolved prior to implant placement to help ensure proper healing. Bite problems and poor oral hygiene leading to gum disease and infection are other oral health issues that can contribute to the failure of dental implants. Gum disease (periodontitis) should be controlled before an implant is placed. Otherwise, the risks of failure due to contamination and infection of the implant site may be unacceptably high.
Dental Implant Failure Due to General Health Problems
Smoking is the most common preventable health issue associated with implant failure. The use of cigarettes reduces blood flow and oxygenation of the tissues in the mouth. It also causes dry mouth. Poor blood flow slows healing substantially and interferes with both blood clotting and tissue regeneration. Lack of saliva allows bacteria to flourish, increasing the risk of infection and tissue inflammation. If the bone does grow in around the implant, this process can take much longer than normal.
Systemic diseases like diabetes may impact the body’s ability to heal by:
- Impairing normal circulation
- Causing chronic tissue inflammation
- Limiting the body’s ability to build or restore bone tissue by causing unwanted hormonal changes
A patient with systemic disease who has a bone graft may need additional healing time before the implant is “loaded” with a crown that must withstand biting and chewing forces. If loading is done too early, the implant may move and the body will reject it rather than bonding to it with new bone tissue.
Certain arthritis medications as well as radiation and chemotherapy can make a patient a poor candidate for dental implants. Very occasionally, a patient may be allergic to titanium, resulting in the body rejecting the implant. Adverse reactions to bovine-sourced bone grafting materials may also occur, but this type of problem is extremely rare.
Dental Implant Failure Due to Dentist Error or Faulty Implants
Even a highly trained dental specialist will have an occasional patient with a failed implant. However, the risk of failure is higher among dentists who are just learning the procedure and those who do not follow best practices during evaluation, selection and placement. Causes of failure may include:
- Incorrect interpretation of CT scans evaluating bone density and volume
- Selection of an implant model with the wrong size, shape, or surface texture for the case at hand
- Improper drilling and/or irrigation technique that can fracture or burn the bone tissue
- Chemical or bacterial contamination of the tools or the implant itself
- Poorly designed crown or bridge that places undue stress on the implant
- Failure to properly prepare the surgical site by addressing existing periodontal disease or bone loss
- Failure to allow sufficient time for healing after bone grafting or implant placement before moving to the next treatment step
Basically, failure of the implant can result from any error in treatment that causes:
- Recession of the gum tissue leaving the implant top exposed
- Excessive bone loss around the implant causing the post to be loose
The implant post, the abutment or the restoration (crown, bridge or denture) can also be implicated in dental implant failure. The tiny screws on some of these implants have been known to break and the implant or restoration may even fracture. This may be due to poor quality materials, or it can be caused by incorrect placement.
Often, it’s not clear whether the fault for an implant failure lies with the patient, the dentist, the dental fabrication lab or the implant manufacturer. That’s because most patients who get dental implants do not have very good oral health to begin with. It’s important to investigate all the possible causes of implant failure to determine the best course of action for treatment.