PERI-IMPLANT DISEASE, A GROWING PROBLEM

Peri-implant disease is unarguably one of the most significant risks associated with implants. It is a multifactorial disease, which if not diagnosed at early stage, can ultimately lead to failure of the implant.




WHAT IS PERI-IMPLANT DISEASE? 
Peri-implant disease is a condition that affects the tissues surrounding a functional implant; it includes both peri-implant mucositis and peri-implantitis. 
Peri-implant mucositis can be defined as ‘reversible inflammatory reactions in the soft tissues surrounding a functioning implant. 
Peri-implantitis is characterised by ‘inflammatory reactions with loss of supporting bone in the tissues surrounding a functioning implant.

Peri-implantitis yields many features in common with chronic periodontitis. 

Both involve alveolar bone loss. 

However, there is a zone of connective tissues which is attached to the root surface in periodontitis. 

In contrast, connective tissue does not attach directly onto implants and there is no periodontal ligament. Therefore, the inflammatory lesion in peri-implantitis extends closer to the bone surface, which can be associated with a faster rate of progression and more aggressive consequences.

AETIOLOGY AND RISK FACTORS

Gram-negative anaerobic bacteria, such as Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans. Bacterial flora that are associated with periodontitis and peri-implantitis are found to be similar

Implants in partially dentate patients appear to be at a greater risk of peri-implantitis than implants in fully edentulous patients. Natural teeth serve as reservoirs for periodontal pathogens from which colonisation of the implant sites occurs.

patient-related risk factors include: inadequate oral hygiene, smoking, parafunctional habits and underlying systemic conditions such diabetes.

occlusal overload will play an important role implant failure by resulting in progressive bone loss around the implant.

Iatrogenic factors such as lack of primary stability, poorly positioned implants, premature loading during the healing period and poorly fitting abutments or restorations.

DIAGNOSIS

 Diagnosis of peri-implant disease relies on crude parameters commonly used for the diagnosis of periodontal disease. 

Swelling and redness of the peri-implant marginal tissues and plaque/calculus accumulation are important signs.

Bleeding on probing and suppuration are clear indications of disease.

successful implants generally allow a probe penetration of approximately 3-4mm in the peri-implant sulcus.

Adequate baseline radiographs determine the peri-implant bone status as well as the marginal bone level. These can then be compared to future radiographs to determine if additional bone loss, beyond ‘normal’ has occurred. Progressive bone loss is a definite indicator of peri-implantitis.

Implant mobility is an insensitive measure in detecting early implant failure

More advanced peri-implantitis is characterised by mobility of the fixture, indicating failure of osseo-integration. 

  

MANAGEMENT

When the main aetiological factor is bacterial infection, the first phase of treatment involves the control of acute infection and the reduction of inflammation. This involves the removal of plaque deposits and improved patient compliance with oral hygiene until a healthy peri-implant site is established.

The implants that are affected with peri-implantitis are contaminated with soft tissue cells, microorganisms and microbial by-products. The defect must be debrided. Prophy jet and the use of a high pressure air powder abrasive has been advocated, as this removes the microbial deposits, does not alter the surface topography and has no adverse effect on cell adhesion.

contact with a supersaturated solution of citric acid have been used for the preparation of the implant surfaces. 

Soft tissue laser irradiation has also been used .

systemic administration of antibiotics that specifically target gram-negative anaerobic organisms has shown an alteration in the microbial composition and a sustained clinical improvement. A local delivery device with fibers containing polymeric tetracycline has been tried and this resulted in significantly lower total anaerobic count.

If vertical 1 to 2-wall defects (< 3mm) are found, then the resective surgery may be used to reduce the pockets, to smoothen the rough implant surfaces, to correct the osseous architecture and to increase the area of the keratinized gingiva.

Various bone grafting techniques and materials and guided bone regeneration, have been successfully used for the regeneration in 3-wall or circumferential defects. 

Porous titanium granules have also recently been advocated to try and treat advanced peri-implant osseous defects

When biochemical forces are considered as the main aetiological factors, occlusal equilibration i.e. improvement of the implant number and position and changes in the prosthetic design, can arrest progression.