A ticking dental time-bomb?

PERI-IMPLANTITIS is a chronic inflammatory process affecting both the hard and soft tissues around dental implants. It has now been well established that all implants may be at risk over the longer term and in recent years this problem has been highlighted both within the dental press in the UK as well as published dental literature.

It is estimated that up to 20 per cent of implants may undergo some degree of bone loss over a 10-year period, with a usual lag period of around six to eight years. The pathogenesis of peri-implant disease follows a similar course to periodontal problems around natural teeth, although it is well recognised that the two disease processes are distinct. Initial soft tissue inflammation around implants, termed peri-implant mucositis, is regarded as a reversible stage where active intervention and management can prevent progressive bone loss occurring around the implant fixture and the development of the established lesion, termed peri-implantitis.

Regular follow-up of patients with dental implants to ensure early diagnosis of peri-implant mucositis offers the opportunity of preventing progression of the disease. Such prevention requires the maintenance of a high level of oral hygiene by the patient in addition to ensuring that any implant has stable keratinised gingival tissue.

Risk factors

A number of risk factors have been identified that may predispose patients with dental implants to peri-implantitis. These include poor hygiene around the peri-implant tissues, cigarette smoking, type 1 diabetes, non-keratinised gingival tissue and a past history of periodontal disease around the natural teeth. Smokers may be further at risk in the treatment of established peri-implantitis lesions. It is therefore important for all clinicians to discuss the relevant risk factors with potential implant patients as part of the overall consent process. Patients identified to be at a higher risk must be made fully aware of this to ensure appropriate informed consent is obtained, and all communication should be documented in the clinical records.

Some of the identified risk factors may be modified in order to reduce the likelihood of developing peri-implant disease. Treatments may include soft tissue grafting, smoking cessation advice and reinforcing the importance of supportive periodontal therapy over the longer term to mitigate the risk of peri-implant disease. Ongoing clinical and radiographic follow-up in addition to patient specific hygiene programmes are also important management strategies to help to minimise the risk of peri-implant complications.

Diagnosis

The diagnosis of peri-implantitis is usually made by a combination of clinical and radiographic assessment. Clinical findings around implants with peri-implant disease may include soft tissue inflammation, bleeding on probing (an important marker of risk) and occasionally there may also be suppuration when probing. Radiographs will usually show evidence of bone loss around the top of the implant and sequential radiographs can be compared to those taken previously to assess any changes in the bone levels occurring over time.

The process of progressive bone loss around dental implants has been likened to the similar process that develops around teeth when periodontal disease is present. While the microbiological flora are similar to those found in periodontal pockets there have been some clear differences identified in the nature of the organisms involved in peri-implantitis lesions. This is not surprising given the biological differences in the periodontal attachment between natural teeth and dental implants.

The inflammatory cell infiltrate in peri-implantitis lesions is usually larger and extends more quickly when compared to similar lesions of periodontitis around the natural dentition. This commonly presents as ‘crater-like’ defects around implant fixtures. Based on the modified soft tissue attachments around dental implants the tissues would appear to be more susceptible to plaque-induced inflammation that may subsequently develop into peri-implantitis-type lesions and this reinforces the importance of meticulous plaque control by patients with dental implants in addition to close follow-up and regular hygiene visits.

Management options

The treatment of peri-implant infection focuses on the management of the infected lesion, decontamination of the implant surface and, ideally, an attempt at regeneration of the lost hard tissue resulting from the inflammatory process. It is still not wholly clear as to the best way to manage peri-implant disease as treatment options can involve both surgical and/or non- surgical options, and the current clinical data suggests that the management of peri-implantitis is unpredictable.

The use of chemical agents such as chlorhexidine has only a limited effect on the microbiological aspects that may influence the ongoing progression of peri-implant disease but its use is still advocated to help decontaminate the colonised implant surface. It is however generally accepted that the establishment of a healthy and non-inflamed peri-implant soft tissue environment is critical in order to prevent progression of these lesions and progressive bone loss around the implant fixture.

One of the significant difficulties in the management of peri-implantitis lesions is the problem of decontaminating dental implants when corrective treatment is being attempted. Dental implants are developed with roughened surfaces with a view to ensuring good osseo-integration at the time of fixture placement (see figure). However, when bone loss does occur this roughened surface becomes exposed to the mouth and rapidly contaminated with dental plaque. A number of options have been put forward for the management of peri-implantitis and these include:

• mechanical debridement with or without systemic antibiotics
• mechanical debridement with local antibiotics
• mechanical debridement with laser decontamination, air-abrasion and proprietary acids to try to remove biofilm from implant surface
• surgical debridement including decontamination of the implant surface with antiseptic agents such as chlorhexidine
• surgical debridement of lesions with bony recontouring and guided bone regeneration.

Despite the range of potential options, the management of peri-implant lesions remains unpredictable even in specialist hands.

Maintenance and follow-up of dental implants

Recent years have seen a steady rise in the number of dental implants placed in UK patients and this trend is only likely to continue – although the UK remains behind some European countries in the number of implants placed per capita. With this inevitable rise in the provision of dental implants it is likely that peri-implant disease will become an all too common presentation for general dental practitioners and specialists to diagnose.

Given the unpredictability of treatment, peri-implantitis is likely to continue to present an ongoing challenge in restorative dentistry. From a medico-legal perspective it is even more important to ensure that patients undergoing dental implant therapy – even under specialist care – have appropriate follow-up both clinically and radiographically to ensure that any peri-implant mucositis or more advanced peri-implantitis is appropriately managed. Ongoing follow-up will ensure that any peri-implant problems can be identified early in order to help prevent progression of these lesions.

Nicholas Lewis is a consultant and specialist in restorative dentistry at the Eastman Dental Hospital in London and in private practice in Hampshire