Treatment of peri-implant diseases: a review of the literature and protocol proposal

Diagnosis and classification

Peri-implant mucositis describes inflammation in the mucosa at an implant area with no signs of loss of supporting bone.3 Diagnosis of peri-implant mucositis is usually by detection of bleeding on probing (BOP), though redness and swelling may also occur (Figure 1a). Peri-implantitis, on the other hand, describes the presence of inflammation in the mucosa at an (osseo-integrated) implant with loss of supporting bone after one year in function. Diagnosis of peri-implantitis is based on increased probing pocket depths (BOP), suppuration (SUP)(Figure 1b), loss of supporting bone, visible clinically on reflection of the soft tissue for surgical treatment (Figure 1c) but usually evidenced radiographically (Figure 1d) and, infrequently, implant mobility is clinically detectable.3 The extent of peri-implant disease may be graded, grade 0, 1, 2 or 3 (Table 1). A more recently described, possibly different disease, ‘retrograde peri-implantitis’ is diagnosed as a symptomatic periapical lesion, which may demonstrate a draining sinus. Radiographically, a periapical radiolucency may be seen, with normal osseointegration of the coronal portion of the implant (Figure 2). This lesion often develops shortly after implant insertion and, in the majority of the cases, requires surgical treatment, the discussion of which is beyond the scope of this paper.4

Prevalence

In large studies, peri-implant mucositis has been shown to occur in 80% of subjects and in 50% of implant sites.3 Prevalence rates for peri-implantitis of 28–56% of subjects and 12–43% of implant sites have been reported. Risk indicators, such as poor oral hygiene, previous history of periodontitis, diabetes and tobacco smoking have all been linked with increased prevalence of peri-implant diseases.5

Aetiology

There are broadly three theories currently proposed to explain the aetiopathogenesis of peri-implantitis:

The microbial biofilm associated with peri-implant disease is mixed and variable, although generally dominated by Gram-negative anaerobic bacteria. Several studies have indicated that peri-implantitis may be associated with an increased proportion of P. gingivalis, T. denticola, F. nucleatum, and A. actinomycetemcomitans. However, other studies identify a diverse spectrum of bacteria, including indigenous oral commensals and bacteria associated with infections of implanted medical devices (eg S. aureus and S. epidermidis). Therefore, the microbes associated with all cases of peri-implantitis may not simply be identical to those in periodontal disease.5 Although biofilm removal is associated with clinical improvement, this does not prove that the biofilm causes the diseases.

In addition to the microbiological theory for implant bone loss, there is also experimental evidence that excessive or adverse loading may cause advancing bone resorption. Clinically applicable evidence is, however, currently somewhat lacking.6 A further postulated theory is that of ‘the compromised healing/adaptation theory’.7 In this theory, implant anchorage is disturbed by poor surgical technique, killing cells needed for repair. Alternatively, a poor host bed response, or excessive strain due to implant misfit or prosthodontic errors, or disturbance of bone cells and their vascular supply, may create an environment predisposing to colonization with pathogenic biofilm, leading to peri-implantitis. The theory of a poor host response is perhaps reinforced by evidence that there are subtle differences in the host response and lesion development in periodontal disease and peri-implantitis.8

Treatment of peri-implant diseases

In spite of the confusion around the aetiology of bone loss around implants, and whether it is a primary or secondary infective process, it is universally accepted that the microbial biofilm plays a central role in the disease9 and its disruption is required for successful treatment. Prior to commencing treatment, iatrogenic factors that may promote peri-implantitis or mucositis should be identified and, if possible, addressed; for example, excess cement, over-contoured restorations or poorly positioned implants.10

Treatment of peri-implant mucositis

Peri-implant mucositis is usually treated by non-surgical mechanical therapy, using carbon fibre (Figure 3a) or titanium instruments (Figure 3b), or plastic insert ultrasonics (Figure 3c, d) to minimize damage to the implant surface and superstructure. Adequate access for professional debridement for the treatment of peri-implant mucositis may require removal and if necessary adjustment of the superstructure (Figure 3e, f). Whether mechanical therapy alone is effective, or requires adjunctive anti-microbial therapy, has been extensively investigated. Human studies have employed non-surgical mechanical therapies with adjunctive abrasive carbonate air powder, or phosphoric acid gel, and demonstrate that peri-implant mucositis can be successfully treated mechanically, with or without these adjuncts. Similarly, there is limited evidence for the adjunctive use of chlorhexidine irrigation and home use mouthwash. However, these are routinely used in practice.11^–14

Treatment of peri-implantitis

While non-surgical periodontal therapy is almost always the first line of treatment for periodontitis, regardless of severity. By contrast, Renvert et al31^,32 conclude that non-surgical therapy alone is not effective in the treatment of periimplantitis. Peri-implantits treatment is further complicated by the design and the surface of the implants. Turned (smoother) implant surfaces demonstrated a 20% reduction in risk of being affected by peri-implantitis over a 3-year period, compared with rougher surface implants.15^,16 Moreover, implant geometry and different surface characteristics may also predispose to peri-implantitis.17 The ultimate aim of treatment of peri-implantitis, similar to that of periodontitis, is regeneration of bone around the fixture, termed re-osseointegration. This has been shown to occur. Again, however, the implant surface exerts an effect. Although smoother surfaces may be slightly less susceptible to peri-implantitis, if affected by bone loss, these surfaces are also less amenable to re-osseointegration (22% re-osseointegration after treatment at turned sites compared with 84% at rougher, SLA™ sites). Biofilm removal is essential to re-osseointegration and this presents a significant challenge to successful treatment, as removing biofilm from rough surface implants is more difficult than its removal from smooth surfaces.18^,19 This is a complex situation, as even different rough surfaces show differences in their ability to re-osseointegrate in beagle dog studies.20 Treatment options for peri-implant diseases are discussed below.

Surgical treatment

There is sufficient evidence demonstrating that non-surgical treatment fails to eliminate or reduce the bacterial counts at sites with peri-implantitis, and that non-surgical treatment alone may not be sufficient to treat peri-implantitis effectively.23 Overall, a recent review of 26 studies estimated that surgical treatment for peri-implantitis eliminated symptoms of peri-implantitis and arrested progression of bone loss over a 5-year period, in 58% of the sites treated. The basis of this surgical treatment is access flap, removal of granulation tissue and implant surface decontamination.24 However, within this framework, there is a wide variety of different surgical approaches to the treatment of peri-implantitis, making analysis of the most successful difficult. The essence of treatment remains to debride the implant surface and the majority of non-surgical mechanical debridement techniques described above have found application in surgical debridement (Figure 4 a–d). More recently, in addition to the titanium scalers described above, a rotating titanium bristle brush has been described for use when surgically debriding implants.25 The options for surface decontamination, antimicrobials, resective vs regenerative and closed vs open healing are discussed in more detail.

Prevention of peri-implantitis

Conclusions

This review aims to present evidence from the most recent studies and systematic reviews24^,45^–47 of the various treatment options for peri-implant diseases.

In conclusion:

Further research regarding the long-term outcomes of the myriad proposed treatment options for peri-implantitis would be useful to clinicians. Ultimately, further advances are required to achieve predictable outcomes.