Peri-Implantitis: What Causes Implant Failure?


How Can Peri-Implantitis Cause Implant Failure?

About 30 years ago, dental implants were thought of as a surefire solution; a permanent, lifelong restoration that will last in the patient’s mouth forever. With the spread of implants over the years, we now know that they don’t come without their post-treatment complications. In fact, a more cautious school of thought is emerging in Implant Dentistry, that view implants as temporary solutions and that failure is eventually inescapable.

As clinicians, we always do everything in our power to ensure the long term success of implant placement. However, dental implants simply fail sometimes; that’s just a fact of life. What can cause implant failure? Well, in a complex environment like the oral cavity, we can expect an interplay between multiple factors that can lead directly or indirectly to that undesired outcome.


Generally speaking, implant failure can be classified into 2 categories: early failure (i.e. pre-osseointegration) and late failure (i.e. post-osseointegration). 

Pre-Osseointegration Failure

This is usually attributed to suboptimal patient’s health leading to inadequate healing post-surgically or to clinical error. In most cases, retreatment can be attempted with an increasing chance of success. Pre-osseointegration can be due to:

  • Surgical trauma at the time of placement (e.g. overheating of bone or structural damage caused by misplacement).
  • Implant surface contamination or infection (e.g. periapical lesions).
  • Pre-existing systemic conditions (e.g. autoimmune disease, osteonecrosis, radiation therapy in cancer patients).
  • Poor bone quality or inadequate bone reduction.
  • Compromised implant initial stability.
  • Premature implant loading. 

Post-Osseointegration Failure

This type of failure is more tricky since it can lead to esthetic, biological and biomechanical complications. Also, it may necessitate removing the implant altogether and allow the implant recipient site to redevelop (as opposed to attempting to regenerate the lost bone) if there’s more than 50% loss in the surrounding bone. Post-osseointegration failure can be due to:

  • Excessive occlusal forces.
  • Parafunctional habits (e.g. clenching).
  • Peri-implantitis 

 Definition of Peri-Implantitis

As the name suggests, peri-implantitis or peri-implant inflammation, is a pathological condition occurring in soft and hard tissues surrounding implants. The inflammation starts in the mucosa around the implant, and is followed by gradual supporting bone loss.

Peri-implant diseases can be divided into mucositis and peri-implantitis. Not unlike gingivitis and periodontitis, the incidence of peri-implant mucositis and peri-implantitis may overlap and the two can be indistinguishable clinically. In other words, the etiology of peri-implant pathology is not yet comprehensively understood.

Peri-Implant Mucositis

A precursor to peri-implantitis, mucositis only affects the soft tissues leaving bony tissues intact. It’s a reversible inflammatory condition which presents clinically as reddened and swollen gums that bleed when probed. 


In addition to gingival inflammation, peri-implantitis also affects the surrounding bony tissues. Since it’s accompanied by bone resorption, it’s irreversible and requires surgical interference. 

Clinical symptoms include: 

  • Reduction in osseointegration
  • Increased pocket depth
  • Bleeding on probing
  • Pus discharge
  • Bone loss (radiographs)

Clinical Signs & Symptoms

Peri-implantitis is characterized by typical inflammatory signs such as redness, mucosal edema, bleeding on probing with or without pus discharge, increased pocket depth and radiographic evidence of bone loss.

Pocket depth in implants showing moderate to severe peri-implantitis has been reported to be around ≥6 mm. That being said, it must be noted that it’s difficult to determine with certainty what represents a normal probing depth around dental implants. 

Most commonly, bone loss occurs in a circumferential pattern with the surrounding crestal buccal and lingual bone intact. Less common is the buccal semicircular resorption pattern around the middle of the implant body. Following that is buccal circular bone resorption with or without lingual plate of bone involvement. Dehiscence-type defects occurring buccally in isolation is the least common of all.

Periapical Peri-Implantitis

These are lesions which are clinically characterized by periapical radiolucency. They can take shape in the presence or absence of classical inflammation symptoms and abscesses. They are usually reported in cases of peri-implantitis which occur next to a natural tooth that has a periapical lesion. 

Peri-Implantitis-Like Lesions

A number of oral lesions occurring in the mucosal tissue, can act in a manner similar to peri-implant inflammation. Although they have many clinical aspects in common with peri-implantitis, they can be distinguished using histopathological differential diagnosis. These lesions include primary malignant oral tumors, metastases and giant cell granulomas.

Risk Factors & Prevention

Having a history of untreated periodontitis, poor oral hygiene and lack of post-operative maintenance measures is strongly correlated with peri-implant disease. Patients with a history of periodontitis are actually 6 times more likely to develop peri-implantitis than those with no previous incidence of chronic periodontal inflammation. Drinking, heavy smoking (identified as more than 10 cigarettes per day) as well as uncontrolled diabetes (with hemoglobin A1c higher than 8), have also been described as potential risk factors.

Studies also reported a number of other factors such as using excess cement which may lead to its accumulation in the submucosal tissues post-operatively, absence of keratinized mucosa around the implant and inadequate positioning of the implant which hinders accessibility for cleaning. However, further research is still needed in this area to acquire more conclusive data seeing as there is no statistically significant correlation. 

To prevent peri-implantitis, every treatment plan should begin with a comprehensive evaluation and assessment of risk factors. We need to clinically verify adequate soft and hard tissue conditions in the implant recipient area as well as ensure proper implant design which is minimally invasive. Implant patients should be followed up regularly and periodontal probing depths must be closely monitored. Pre-, intra-, and post-operative radiographic evidence should be documented to keep an eye on any changes occurring in the implanted site.


The prevalence of peri-implant disease has been estimated to range from 19-65% for mucositis and from 1-47% for peri-implantitis. It’s been reported that after 5-10 years, peri-implantitis will develop in 10% of implants in 20% of patients. With the increasing number of implants we place in our daily practice, it’s safe to assume that the incidence of this pathological condition will increase correspondingly. It’s therefore necessary to be up-to-date with the most evidence-based treatment protocols and surgical interventions.


 Peri-implant mucositisPeri-implantitis
Prevalence (range)

19 to 65%

1 to 47%

Estimated weighted mean prevalence

43% (CI: 32-54%)

22% (CI: 14-30%)


Therapeutic measures of peri-implant disease include surgical and non-surgical modalities. The treatment of choice will depend on the severity of the inflammation (i.e. peri-implant mucositis, moderate or severe peri-implantitis). Non-surgical management by itself can be sufficient in cases of mucositis, however in advanced peri-implantitis cases, a combination of both surgical and non-surgical interventions may be necessary.

Treatment of Mucositis

Disinfection of the affected implant surface should be the goal of the treatment. Local debridement of the implant surface using titanium or plastic-curettes, ultrasonics or air polishing is advised. Additionally, phototherapy and locally-administered antiseptics (e.g. chlorhexidinglukonate, hydrogen peroxide, sodium percarbonate, povidone-iodine) can enhance antimicrobial activity.

A routine oral hygiene protocol should be in place to prevent peri-implant mucositis. Plus, maintenance measures done by a dental professional at regular intervals are recommended as an essential part of post-operative implant care. 

Treatment of Peri-Implantitis

The vast majority of treatment strategies for peri-implantitis are similar to those used in treating periodontal disease. That’s because the bacterial biofilm behaves similarly in both inflammatory conditions. Although peri-implantitis is also a poly-microbial anaerobic pathology, its lesions contain bacterial strains which aren’t normally found in the microbial biofilm of periodontal lesions. Namely, Staphylococcus aureus, which seems to be a leading cause for the onset of peri-implantitis since it exhibits high affinity to titanium particles.

Treatment methods include non-invasive (i.e. non-surgical) and surgical (i.e. resective or regenerative) protocols.

Non-Invasive Therapy

Anti-infective therapy and implant-surface decontamination can be used in conjunction with other novel conservative techniques such as ultrasonic and laser treatment as well as photodynamic therapy.

Scaling & Polishing

In order not to make the implant surface rough, metallic and ultrasonic scalers should be avoided. As a general rule of thumb, instruments that are less hard than titanium are recommended. These include, non-metallic scalers, curettes made of titanium, carbon fiber, teflon or plastic (i.e. resin) and polishing rubber cups.


Local administration of antiseptic solutions such as 2% chlorhexidine or 3% hydrogen peroxide can be utilized. Implants surface can be decontaminated using air powder abrasive technique and applying chlorhexidine- or saline-soaked gauze.


Studies show that locally-administered antibiotic drugs do decrease, with no negative outcomes, probing depth as well as bleeding on probing in peri-implantitis cases. We can get an extra 0.30 mm reduction in pocket depth by using antibiotics. When antibiotic therapy isn’t locally applied, bleeding on probing incidence is doubly increased. That being said, it must be noted that different strains of bacteria can develop varying degrees of antibiotic-resistance.

Surgical Intervention

Resective Surgery

Ostectomy, osteoplasty and decontamination are implemented in order to remove the bony defects surrounding the implant. Generally speaking, it’s recommended that we limit surgical resection measures to posterior (i.e. non-esthetic) implant locations. Resective surgery in combination with smoothing the implant surface can increase the treatment success rates of rough-surfaced implants suffering from peri-implantitis. Additionally, this procedure reduces pocket depth, suppuration, and bleeding.

Regenerative Surgery

Regenerative measures are required in cases of major bone resorption. To obtain ideal esthetic, biological and biomechanical properties and prevent further failure, re-osseointegration through bone regeneration is a must. This method has been reported to be more effective than submucosal debridement and decontamination alone. The use of xenograft tissues with resorbable materials is advantageous for regeneration purposes.

Both bone grafting and guided bone regeneration have demonstrated success in post-surgical healing and tissue reattachment. Using natural bone and collagen can enhance the survival rates of the implant as well by improving the treatment outcomes.


So is implant failure inevitable? Well, for the more pessimistic among us, this slightly paraphrased quote from the author Chuck Palahniuk comes to mind: 

“On a long enough timeline, the survival rate for [everything] drops to zero.”

However, to look on the bright side, we know for a fact that peri-implantitis is a preventable and treatable pathological condition (putting aside those few researchers who still don’t consider it a disease). The preventive measures can be established before even considering implant treatment. That’s to say, we need to have periodontitis and plaque under control as well as have  proper oral hygiene and maintenance protocol in place first and foremost.

A lot of operator-related factors can be avoided with proper three-dimensional treatment planning using dental software. Digitally-guided implant surgery can help us prevent malposition of implants too buccally as well as visualize the surrounding implant-recipient field. Guided implant placement eliminates a large portion of potential error that might cause complications 6-12 months after treatment. Using proper protocols in combination with adequate planning and prevention can mean the difference between a reversible post-surgical complication and implant loss.

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