On one fine day you are sitting in your dental clinic and you get a call from your patient where he is complaining of some problem with the dental implant prosthesis which you placed few weeks before. You have earlier explained the client about all the post-insertion instructions, so you seem to be little apprehensive about the possible cause of the problem. When the patient visits to your clinic next day, you take the necessary radiograph only to see that there is a substantial bone loss which one supplemented by clinical examination led to informing the patient that the implant has failed. This comes as a shock for both you and the patient. The patient as he has paid a handsome amount on the implant and for you who has done everything right during the dental implant placement. This also led to some basic questions by patients like, why did the dental implant fail? Can we save it? Will I get my implant replaced? What are the chances of the second one if I go for another one? Many of these questions which you wish have never been asked to you!

So, why do dental implants fail? This is the burning question that confronts most of the implantologists today when it comes to failure and complications associated with an osseo-integrated dental implant.

It is beyond any doubt that over the two decades, dentistry has undergone many changes, but none of them have been more profound than those in the field of implant dentistry. Now as its scientific fundamentals and principles are established, this branch of reconstructive surgery has moved out of the process of mere empiricism and wishful thinking. However, in spite its scientific background coupled by skillful placement and relatively high success rate, the clinicians also faced with dental implant failure. Therefore, a sound and through knowledge regrading various causes and facets of implant failure is deemed necessary.

What is dental implant failure?

Dental implant failure can be defined in various ways. When the performance of the implant, measured in some quantitative way falls below an acceptable and specified level, the implant is considered as failure. Also, when the dental implant fails to fulfil is very purpose of placement which could be esthetics, functional or phonetics or its inadequacy to maintain osseointegration with host tissue it is termed as failure.

Signs and symptoms of dental implant failure:

Signs and symptoms of implant failure include, difficulty in chewing, gum inflammation, swelling around implants, loosening of implant and severe pain and discomfort. Radiographically loss of bone is seen around implant

Common factors impacting dental implant success and failure

  • Diseases of gum and periodontium: Healthy gum increases the chances of implant success by many folds. Patients with diseases like gingivitis or periodontitis may jeopardise the health of the implant and could lead to failure.
  • Insufficient bone around implant: An adequate and healthy bone is paramount for implant success. Conditions like osteoporosis or disease which could lead to thinning and undermining of bone can have detrimental effect on implant success.
  • Smoking: Smoking not only have the deleterious effect on overall health but also on dental health. Smoking led to constriction of arterioles which supply blood to periodontium and slow the healing process. Although smoking is not a strict contraindication for implant placement, however the success of it depends on the abstinence of smoking for at least few moths post implant placement.
  • Medical condition: Failure of dental implant is also inevitable if you are suffering from any auto-immune disease like rheumatoid arthritis and diabetes. Here being a foreign object the implant gets rejected and it also slows down the bone healing process. This in turn impair the osseo-integration and led to implant failure. Few researches have also mentioned the use of certain medication like the ones used for heartburn or used as antidepressants, bisphosphonates can also affect fusion of bone with implant and lead to failure of the place implant.
  • Poor oral health maintenance: Even though the dental implant is placed with a good amount of bone, absence of meticulous oral hygiene practice can jeopardise the health and longevity of the implant.
  • Iatrogenic factors: In spite of overall good oral and general health sometimes due to inexperience of the clinicians or poor choice of implant material or faulty placement technique can lead to failure of implants.

Types of dental implant failures:

Various classification of implant failure has been reported in literature, some of which are following:

  • Classification by Nallaswamy:
    • Due to systematic factors
    • Due to surgical complications
    • Failure due to implant prosthesis
  • Esposito classification:
    • Biological failure
    • Mechanical failure
    • Iatrogenic failure
    • Failure due to inadequate patient education
  • Rosenberg classification:
    • Infectious failure
    • Traumatic failure

Commonly used is the working classification which classify dental implant failures into:

1.Early failure (within 3-month or intra-operative)

  • Due to aetiology:
    • Implant selection: improper type (in terms of length and diameter) and placement of implant, surface impurity and roughness
    • Surgical imperfections: lack of initial stabilization, over-heating of bon, improper spacing between implants, implant contamination
    • Restorative imperfections: improper design and occlusal rehabilitation, excessive loading, implant fractures etc.,
  • Iatrogenic: Less experience and expertise of the clinicians, improper design and manufacturing at the laboratory
  • Due to peri-implantitis or inflammation of the bone around implant
  • Lack of osseo-integration

2.Late failures (3-month post-operative)

  • Aetiological factors:
    • Host factors: Systemic disease like diabetes, rheumatoid arthritis, osteoporioiss etc.,
    • Smoking, para functional habits
    • Radiotherapy
  • Due to lack of maintenance on the patient part
  • Functional and psychological problems
  • Overloading, improper occlusion, retrograde implantitis

How to prevent dental implant failure?

Even though amid large success of dental implants, there has been many instances of implant failures also. However, some steps can be taken to reduce the chance and frequency of such failures like:

  • Follow dental implantologists or clinicians’ instructions religiously. Keep the oral hygiene at the optimum level
  • Dietary increase of calcium containing foods like milk, yoghurt, cheese can also aid in rapid bone generation
  • Avoid abusive habits like smoking, alcoholism and para-functional habits
  • Avoid immediate tooth replacement after an implant procedure

Overall, difficulties can occur with any biomechanical object in the area of biological function, as well as mechanical or engineering stability. There have been compromises and complications with implant prosthodontics, which are difficult for both patients and prosthodontists. For any clinician, anticipating adverse implant events and awareness of the treatment of failed implants is necessary. Choosing cases that provide optimal surgical and prosthetic conditions and carefully avoiding complex clinical problems will improve favourable outcomes by avoiding certain conditions that contribute to poor outcomes. It is therefore mandatory for any clinician to know how and why dental implant failures occur and how best we can avoid them in order to give a new horizon this awesome dental prosthesis.