Treatment of Peri-implantitis: Fiction or Reality? Part 1: Non-surgical and Surgical Management

A classification for peri-implant health and diseases was published in 2018 and subsequently modified in 2023 (Table 1).^1,2 Peri-implant health is characterized by the absence of: erythema; bleeding on probing; swelling; and/or suppuration. However, it is not possible to define a range of probing depths compatible with health.¹

Peri-implant mucositis is mainly characterized by bleeding on gentle probing, a decrease in probing resistance, erythema, swelling, and/or suppuration.¹ Peri-implantitis was defined as a plaque-associated pathological condition occurring in tissues around dental implants, which is characterized by inflammation and progressive loss of supporting bone.¹ Peri-implantitis sites show clinical signs of inflammation, bleeding on probing and/or suppuration, increased probing depths and/or recession of the mucosal margin, in addition to radiographic bone loss.^1,3

The successful management of peri-implantitis is based on the evaluation of composite therapeutic endpoints that correspond to disease resolution. These include the presence of shallow pockets with no bleeding on probing (BoP) or suppuration, and the maintenance of radiographic bone levels. As clinical signs of pathology are more frequent in implants with progressive bone loss,⁵ a probing pocket depth (PPD) of 5 mm with no BoP may predict the cessation of bone loss and the successful outcome of peri-implantitis therapy.^6,7 In addition, secondary outcome measures such as inflammatory biomarkers in peri-implant crevicular fluid (PICF) and microbiological assessment of subgingival mucosal plaque samples may be used.

Currently the treatment of peri-implantitis remains a clinical challenge.⁶ Applied treatment modalities for peri-implantitis¹ have hitherto been based on the assumption of its aetiological similarity to periodontitis, and therefore, anti-infective protocols, which aim mainly at resolving inflammation and arresting the disease progression by controlling the subgingival bacterial biofilm,⁷ have been adopted for its treatment. For instance, peri-implant mucositis, a reversible inflammatory process of peri-implant soft tissues without supporting bone loss,¹ can be successfully treated by supra/submucosal mechanical debridement, in conjunction with the administration of local antiseptics and preventive measures to reinforce oral hygiene.^8,9 Although peri-implant mucositis shares certain similarities with gingivitis, experimental peri-implant mucositis leads to a greater increase in bleeding sites compared with experimental gingivitis, and may take longer than 3 weeks for clinical reversibility.¹⁰ Peri-implantitis treatment often consists of a combination of non-surgical, submucosal instrumentation, followed by surgical flap procedures to provide access for debridement and decontamination of the exposed implant surface and, in some cases, with the reconstruction of the resulting osseous defects by means of bone grafting and barrier membranes.¹² The mechanical disruption of the biofilm in both non-surgical and surgical approaches has been combined with the adjunctive use of antibiotics (local/systemic),¹³ local chemical agents, laser or air-powder abrasives.¹⁴

A recent consensus statement⁹ has indicated that prosthetic overcontouring (emergence angle >30° combined with a convex emergence profile of the abutment/prosthesis) is associated with an increased risk for peri-implantitis.¹⁵ Furthermore, it appears that reconstructive peri-implantitis treatment may facilitate the maintenance of post-operative peri-implant soft-tissue levels (Table 2).¹⁶

Therapeutic strategies for the management of peri-implant diseases have been described in the literature.^17,18 Historically, literature has delineated a cumulative interceptive supportive therapy protocol¹⁷ for the prevention and management of peri-implant diseases. Recently, the European Federation of Periodontology (EFP) has recently introduced the S3 level clinical practice guideline for the prevention and treatment of peri-implant diseases, which outlines specific therapeutic gruidelines and establishes objectives for treatment (Table 3).⁴

For example, systematic reviews^7,19 have suggested a four-phase treatment strategy for peri-implantitis:

• Pre-treatment phase to include oral hygiene and risk management, prosthesis assessment, adjustment and removal if required, and non-surgical debridement with or without antimicrobials.
• If resolution is not achieved, surgical access is indicated by means of a mucoperiosteal flap for implant surface decontamination and modification or reconstruction of osseous defect with a bone graft substitute with or without a membrane.
• Post-operative anti-infective control, e.g. chlorhexidine rinses as adjuncts to routine oral hygiene practices.
• Maintenance care on a regular basis.

Finally, when faced with the clinical challenge of the failure of a surgical or regenerative treatment (Figure 1) or with cases of severe bone loss coupled with possible complications, such as unfavourable implant position or prosthetic failures, then explantation is recommended.^20,21,22

Given the complexity of peri-implantitis treatment, it is fundamental to:

• Perform a risk estimation and management at patient and site level;²³
• Discuss relevant information on the periodontal status of the remaining dentition and patient-reported outcomes with patients;²⁴
• Highlight the importance of prevention, early diagnosis and early management of peri-implant mucositis;
• Highlight the importance of regular and thorough maintenance (supportive periodontal and peri-implant care).

The above reinforces the need for clinicians to identify and optimise modifiable risk factors prior to implant placement, and to use this information to inform patients of their individual risk profile during the consent process. The Implant Disease Risk Assessment (IDRA) is a risk stratification tool that helps to estimate the risk of a patient developing peri-implantitis.²³ Therefore, the decision whether implant treatment should be performed should be based on an assessment of the patient's risk profile at the patient level, as well as at the site level (Figure 2).²⁵

Non-surgical treatment of peri-implantitis

Non-surgical mechanical plaque control could be effective in the treatment of peri-implant mucositis through the reduction of bacterial load and inflammation within peri-implant soft tissues. In peri-implantitis therapy, non-surgical treatment protocols are considered the first step of management, which also serves to optimise patient's oral hygiene, risk factor profile and marginal tissues for the next phase of treatment.²⁶ However, various instruments and approaches, aimed at removing both supra- and subgingival biofilm, such as plastic, carbon or titanium curettes, sonic or ultrasonic scalers, rubber polishers, and air-powder flows, have been proven to be insufficient to ensure complete removal of bacteria on implant surfaces, and have only a moderate short-term effect on the improvement of clinical parameters (such as a reduction in PPD),^9,27,28 radiographic or microbiological outcomes (Figure 3).⁹ In addition, the effect of the cleaning methods on different implant surfaces, such as the use of plastic scalers, titanium brushes and air-abrasive systems, may lead to surface topography modifications on rough and smooth titanium implants.

Despite evidence that some specific surface decontamination protocols may be effective in reducing bacterial load, clinical pocket depths and peri-implant mucosal inflammation, non-surgical treatment of peri-implantitis has often been reported as insufficient for disease resolution. Moreover, one study reported that 11% of patients had at least one implant removed during surgical treatment of peri-implantitis or at some time point after surgery because peri-implantitis had reached its terminal stage, and implant loss was unavoidable.²⁹ Notably, no single method of non–surgical implant surface instrumentation decontamination has been found to be superior.³⁰ Part 2 of this series discusses in detail the evidence in relation to adjuvant antimicrobial and decontamination modalities following non-surgical and/or surgical treatment of peri-implantitis.

In order to potentiate the effectiveness of mechanical plaque control, several clinicians have suggested the adjunctive use of other antimicrobial therapeutics or approaches. Currently, there is limited evidence regarding the use of systemic antimicrobial protocols as adjuncts to mechanical therapy, which hinders robust conclusions regarding their effectiveness considering possible side effects (e.g. antibiotic resistance) and increased cost (e.g. laser equipment).³¹ Larger randomized controlled clinical trials are still required to assess their effect on clinical outcomes. Specifically, FGDP (UK) and European Federation of Periodontology (EFP) S3 level clinical practice guidelines do not recommend systemic or local antimicrobials for peri-implant mucositis. However, local measures to improve self-care oral hygiene are strongly recommended. Similarly, FGDP (UK) does not recommend the use of antimicrobials as an adjunct to local management of peri-implantitis.^4,32

Surgical treatment of peri-implantitis

Current surgical treatments for peri-implantitis, such as access flap, reconstructive, resective, and combination approaches, include the removal of the peri-implant inflammatory granulation tissue and the decontamination of the exposed implant surface.^3,12,33,34 According to the current EFP S3 level clinical practice guideline for the prevention and treatment of peri-implant diseases,⁴ there is insufficient evidence to recommend the use of implantoplasty. However, the use of implantoplasty has been considered in specific cases, in conjunction with regenerative or resective surgery. ^35,36,37

The modification of the implant surface by implantoplasty (Figure 4), along with a resective surgical approach (performed on supracrestal/horizonal, infrabony and some combined defects), has also been proposed as an effective treatment for peri-implantitis.³⁹ Clinical improvements following the surgical treatment of peri-implantitis are usually measured against clinical parameters, such as reduction of PPDs, absence of BoP and radiographic bone fill of bony defects indicating long-term stability.^3,38,39 However, 2 years after therapy, 50% of patients continued to exhibit signs of peri-implantitis.^29,40 Notwithstanding, careful consideration should be given to this surgical approach, as implantoplasty procedures can lead to implant mechanical complications (implant fracture), and to the release of nanometre-sized particles that can trigger local-level reactions, and the full systemic effect is not fully understood at present.^37,41

As previously described for non-surgical treatment of peri-implantitis, many implant surface decontamination procedures have been suggested as part of surgical treatment, through the use of carbon or plastic curettes, ultrasonic scalers, titanium brushes, air-polishing devices using sodium bicarbonate or glycine powder, irradiation with hand or soft laser light, photodynamic therapy or the application of acids or various antimicrobial agents.^18,42 While these studies report on the efficacy of these procedures, the role of implant surface characteristics may also influence treatment outcomes.⁴³

One study evaluated the effect of surgical treatment of peri-implantitis in a preclinical setting, using different anti-infective procedures, such as surgical debridement of the implant sites, in conjunction with either normal saline or 0.2% chlorhexidine, comparing different implant surfaces.⁴⁴ It was shown that:

• The local use of chlorhexidine has minor effects on treatment outcomes;
• Resolution of peri-implantitis was possible without the use of adjunctive local and systemic antibiotics;
• The results were influenced by implant surface characteristics.

A randomized controlled clinical trial has suggested that treatment outcomes for implants with a modified surface had significantly lower odds for treatment success.¹³ They mentioned that the use of adjunctive systemic antibiotics, such as oral amoxicillin 750 mg twice daily for 10 days, was likely to yield positive effects in patients with implants with modified surfaces.¹³ However, more recently, this study reported 3-year follow-up results that indicated that the potential benefits of systemic antibiotics are not sustained over this period, although the surgical treatments were still deemed to be effective.¹³

Further studies are needed to clarify the effect of implant surface characteristics on treatment outcomes⁴⁵ and the influence of adjunctive use of antibiotics on treatment outcome is still unknown. Furthermore, adequately powered randomized controlled trials in this area of research are of high priority.⁴⁶

Regenerative procedures

A meta-analysis of treatment outcomes¹² identified the main surgical procedures that are predominantly performed in the surgical access phase:

• Access flap debridement;
• Surgical resection;
• Regeneration with bone grafts;
• Guided tissue regeneration.

The outcomes of regenerative therapy are reported to be the most variable.¹² It is important to emphasize that, overall, peri-implantitis lesions do not respond predictably to either non-surgical or surgical treatments.

In terms of regenerative therapy, autogenous bone, allogenic decalcified freeze-dried bone, xenogenic de-proteinized bone mineral, phytogenic calcium carbonate, hydroxyapatite or tri-calcium phosphate and porous titanium granules (PTGs),⁴⁷ with or without employing e-PTFE, collagen or resorbable synthetic membranes, have been used in an attempt to reconstruct peri-implant defects and attain bone regeneration. A meta-analysis demonstrated higher reduction in PPDs and BoP when using bone grafts and barrier membranes, in comparison to employing grafts alone.¹² However, as reported in a recent systematic review and meta-analysis, it is important to highlight that there is lack of evidence suggesting improved aesthetic or patient-reported outcomes following reconstructive therapy at peri-implantitis-related bone defects.⁴⁰

A recent randomized multicentre trial demonstrated the benefits of bone grafting in combination with an open flap debridement (OFD) procedure for the treatment of advanced peri-implant osseous defects compared with OFD alone.⁴⁷ Both surgical treatment approaches included the use of a titanium brush for implant surface decontamination and adjunctive systemic antibiotics. Although no significant differences were observed regarding BoP and PPD reduction between the groups, the radiographic bone fill was superior in the group including the bone grafts. The challenge of achieving a successful regenerative therapy in peri-implantitis will greatly depend also on the patient's systemic conditions and the morphological configuration of the peri-implant bone defect, in relation to the number of bone walls that determine its configuration.^3,13,34,48 Furthermore, it has been reported that good oral hygiene plays a pivotal role in long-term stability (4-year follow up) after regenerative treatment of peri-implantitis (combining a xenograft and a collagen membrane).⁴⁹ Regardless of the chosen surgical method and biomaterial use, attaining resolution of peri-implantitis remains challenging. Over the long term, several implants might experience disease recurrence, requiring further surgical interventions or potentially resulting in implant loss.⁵⁰

Re-osseo-integration

The ultimate goal of surgical regenerative treatment of peri-implantitis should be re-osseo-integration: the growth of new bone in direct contact with the previously contaminated implant surface.^50,51 Therefore, regenerative surgical treatment should aim to:

• Ensure substantial regeneration of bone from the walls of the defect;
• Decontaminate the implant surface to facilitate re-osseo-integration.⁵¹

Pre-clinical studies have reported that re-osseo-integration can be achieved in previously infected titanium surfaces.⁵² In two studies investigating the direct influence of surface decontamination on re-osseo-integration, it was demonstrated at a histological level following re-implantation of previously plaque-infected and decontaminated dental implants into freshly prepared osteotomies in dogs.⁵² Similar results were reported in another preclinical study where electrolytic cleaning of previously infected implant surfaces promoted their re-osseo-integration in fresh osteotomies.⁵³ However, there was considerable variability within and between studies, where histological evidence of re-osseo-integration was unpredictable, and may not have been achieved for the entire (previously) contaminated implant surface.¹²

Re-osseo-integration might be influenced by a number of factors, including the implant material, design and surface characteristics, exhibited bacterial communities and host state, surgical site and technique, loading conditions and time.⁵⁴ As such, direct comparison of bone-to-implant contact figures between studies can be difficult.

Following the treatment of peri-implantitis by employing a regenerative approach, large variations in the amounts of re-osseo-integration, from 1% to 84% have been reported.⁵⁵ The implant surface characteristics could be one of the factors responsible for this variability.⁵⁶ It is well known that bacterial adherence is enhanced by the micro-irregularities of implant surfaces, and as long as contamination is present, wound healing will be variably compromised.⁵⁵

Conclusions

It is advised to adhere to the EFP S3 level clinical practice guidelines for peri-implant disease prevention and treatment, implementing a standardized protocol for peri-implantitis management. The following factors merit consideration:

• Patients' risk profile at an individual and site level should be evaluated prior to the commencement of a treatment plan, with specific attention to medical and lifestyle risk factors for peri-implant and periodontal diseases.
• Non-surgical implant surface instrumentation with or without adjunctive chemotherapeutics, or other antimicrobial strategies, has a moderate, short-to-mid-term improvement in clinical parameters.
• In the surgical treatment of osseous defects among peri-implantitis patients, considering an access flap with or without reconstructive measures is viable. To date, no evidence has established the superiority of any particular reconstructive surgical approach. The routine use of adjunctive antibiotics in the surgical treatment of peri-implantitis is not recommended by current guidelines. Given the complexity of surgical treatment for peri-implantitis, it is recommended for it to be conducted by dentists with specific training or by specialists.
• Reconstruction of peri-implant bone defects with new bone formation and re-osseo-integration has been reported with various degrees of success, which may be influenced by various factors including defect morphology, material selection and implant surface characteristics. Furthermore, it has been suggested that reconstructive procedures should be preferably be applied at intra-osseous defects with a depth of ≥3 mm.

A substantial knowledge gap persists regarding the optimal implant surface decontamination protocol. To date, none of the clinically described methodologies has demonstrated total biofilm elimination.

Further research is required in the development of biomaterials with antibacterial potential and osteo-inductive properties that can be used in the context of regenerative treatment of peri-implantitis.