Peri-implant diseases: an overview

Non-surgical approach

This approach involves mechanical debridement of the peri-implant tissues and the affected implant surface without raising a flap. In general, this method is not always effective, particularly when the peri-implantitis is associated with a deep PPD.^10,24 Furthermore, the outcome of non-surgical treatment of peri-implantitis was not predictable and mechanical debridement alone may be efficient when the PPD is shallow,³² but not enough when the PPDs are deep and with exposed implant threads.⁶³ However, the use of mechanical debridement alone was not found to achieve considerable re-osseointegration,⁵⁷ which is an important treatment outcome.

It would seem rational to combine the mechanical debridement with chemical antiseptic agents.^64,65,66 In a human study⁶⁶ of oral implants with an initial to moderate peri-implantitis, the use of carbon curettes combined with chlorhexidine antiseptic was compared with the use of air-abrasive devices alone. Both treatment measures led to comparable but limited reductions in PPD and in CAL gains at 6 months.⁶⁶ However, the result of the study indicated that the first treatment regimen was less effective in decreasing BoP than the second one. It was found that, in peri-implant lesions with a PPD ≥ 5 mm, the combination of mechanical debridement and antiseptic therapy may provide an improvement in clinical parameters. However, residual defects remain after the therapy, which may require additional treatment. According to Renvert et al⁶⁵ the addition of antiseptic therapy to mechanical debridement does not provide adjunctive benefits in shallow peri-implant lesions (mean PPD <4 mm). Therefore, it may be concluded that the use of antiseptic agents as an adjuvant to mechanical debridement is needed in deep PPD. However, surgical intervention may also be required.

It was demonstrated^2,65 that the adjunctive use of a topical antibiotic, minocycline microspheres, to mechanical debridement tends to have greater benefits than those achieved through the use of an antiseptic, ie chlorhexidine and mechanical debridement together. In the study conducted by Renvert and co-workers,⁶⁵ where 32 subjects had peri-implant lesions with a PPD ≥4 mm with BoP and/or exudate, the adjunctive use of chlorhexidine resulted in limited reduction of BoP, but the adjunctive use of minocycline led to improvements in both BoP and PPDs. The observed improvements in bleeding scores and PPDs obtained by the adjunctive use of minocycline were maintained during a period of 12 months. In another study conducted by Renvert et al,⁶⁷ using the same treatment protocols as used in the previous study, the treatment was repeated three times: baseline, one and three months. Follow-up examinations were carried out at 10 days and at 1, 3, 6, 9 and 12 months. The results of this study indicated that the use of minocycline microspheres as an adjunctive is beneficial in the treatment, but the treatment may have to be repeated. This raises the question as to whether peri-implantitis with deep PPD can be adequately treated non-surgically by a combination of mechanical debridement and a local antibiotic, and whether the positive effect of this treatment can be maintained for a longer period of time. Hence, well-controlled randomized clinical studies are required.

Lasers are used currently in dentistry and their use has extended to the treatment of peri-implant diseases. For instance, Thierbach and Eger⁶⁹ divided 28 patients with peri-implantitis into two categories: those with peri-implantitis with pus formation (Figure 3) and those without. Both groups were treated using the same protocol initially after microbiologic diagnosis. All patients were treated at baseline with full-mouth scaling and root planing. Two months later, full-mouth scaling and root debridement and antimicrobial photodynamic therapy were applied. The study indicated that the presence of pus influences the clinical outcome of the treatment of peri-implantitis. According to this investigation, non-surgical treatment of peri-implantitis may be effective when the peri-implantitis lesion has no pus formation but not when pus is present. Nevertheless, when the lesion is associated with pus formation, it can be successfully treated with a supplementary access flap surgery following an additional observation time of 3 months.

It should be emphasized here that, although the use of lasers for implant surface de-contamination is a promising treatment method, their use may be associated with implant surface changes that may negatively affect the treatment result. Furthermore, laser irradiation may raise the temperature beyond the degree which the peri-implant tissue can tolerate and leads to its damage.^58,66 Likewise, not all laser types are suitable as implant surface decontaminators. For instance, YAG and Ho:YAG were not found to be appropriate as implant surface decontaminators, irrespective of the power output.^58,66 Additionally, the application of laser results in an increase in implant surface roughness that may encourage more plaque accumulation and complicates its removal.⁶⁸ Thus, the proper laser type, irradiation angle and energy intensity and application time that is suitable for each implant surface should be recognized and used.⁵⁸

Surgical approach

Surgical treatment of peri-implantitis lesions can be performed after the acute infection has resolved and proper oral hygiene has been established.^2,32,70 The primary objective of surgical treatment in peri-implantitis is to get direct access to the affected site and the implant surface, which facilitates decontamination of the implant surface and eliminates granulation tissue. The selected surgical protocol is also dictated by the degree and morphology of the peri-implant bony defect. The amount and quality of the remaining peri-implant soft tissue may play a role in surgical protocol selection.² The surgical approach can be categorized as follows:

Access surgery (an open flap technique): This approach consists of raising a flap, removal of granulation tissue and debridement/decontamination of implant surfaces.^55,56,59 This method provides a direct vision and access to the affected peri-implant tissue and to the unexposed implant surface. The effect of this treatment was evaluated clinically, microbiologically and radiographically at 6 months, 1 year and 5 years after surgical exposure and implant surface decontamination using curettes and sterile saline.⁵⁵ Systemic antibiotics were also given according to a susceptibility test of target bacteria. Six implants of the 26 studied demonstrated bone gain while seven implants were lost and four continued to lose more bone. Nine implants revealed unchanged peri-implant bone levels. This study indicated that the treatment protocol used may be useful in controlling peri-implantitis lesions but with a low predictable value. However, the number of implants used in the study may preclude from drawing a valid conclusion and further well-controlled studies are important. Heitz-Mayfield et al⁵⁹ studied moderate to advanced peri-implantitis lesions in 36 implants in 24 partially dentate patients. They were treated with open flap surgery and implant surface decontamination using titanium-coated Gracey curettes or carbon fibre curettes and rubbing of the implant surface with gauze soaked in sterile saline. Adjunctive systemic antibiotics (amoxicillin and metronidazole) were also prescribed. Clinical parameters such as BoP, PPD and suppuration were evaluated at 3, 6 and 12 months and the treatment outcomes were analysed during these intervals. Forty seven percent of the affected implants had complete resolution of inflammation (BoP negative) and stable crestal bone levels or bone gain, which was seen in 92% of implants. It was concluded that the conducted treatment protocol was effective and it was possible to maintain the three month positive treatment outcomes for at least one year post-operatively if a strict oral hygiene protocol was followed.

The use of an access flap for debridement of the implant surface combined with chlorhexidine irrigation was compared with non-surgical scaling before photodynamic therapy was implemented for microbial reduction in ligature-induced peri-implantitis in dogs.⁷¹ This investigation reported that several bacterial species, that are believed to be associated with peri-implantitis, were significantly reduced by both treatments. However, photodynamic therapy is a non-invasive approach which may be an advantage over surgical access.⁷¹

It may be concluded that the open flap technique permits direct access into the affected site, which may enable the clinician to evaluate the bony defect and to debride the implant surface and also eliminate the granulation tissues effectively. In addition, this approach may be necessary when the PPD is deep or when the angulation of the implant body is in an inconvenient position that may preclude effective treatment.

Resective surgery (with or without implant surface modification): Resective surgery is used in treatment of periodontal diseases to correct soft and hard tissue defects around natural teeth. It is based on periodontal pocket elimination, such as apical repositioning flap and gingivectomy or pocket reduction to make the periodontal tissue more accessible for cleaning, thus facilitating the patient's oral hygiene. Resective surgery may also involve an osseous resection/re-contouring which means the removal of defective/correction of supporting bone. This resective treatment option is extended for use in treatment of peri-implantitis lesions. In the oral implant, it is carried out in the treatment of peri-implant disease in order to reduce PPD. It may involve correction of the peri-implant soft tissue when the bone loss is mainly of the horizontal type. Resective surgery combined with apical repositioning flap may be performed in the treatment of peri-implantitis that results in a two- or one-walled bony defect or horizontal bone resorption. However, the resective approach should be carried out cautiously as the amount of removed peri-implant tissues may compromise the aesthetic and/or mechanical results of the implant and the neighbouring teeth.

In a clinical study of 31 subjects with clinical signs of peri-implantitis, 42% of the implants still had the disease after two years of treatment with bone re-contouring and pocket elimination and plaque control before and following the surgery.⁷² Seventy four percent of the implants with an initial bone loss of 2–4 mm as measured radiographically showed no sign of peri-implantitis during the 2-year period in comparison with 40% of the implants which had a greater bone loss (≥ 5 mm). These findings reflected the effects of the severity of initial peri-implant bone loss on the treatment outcome and on the stability of the achieved improvement.

A combination of resective surgery and modification of the implant surface (implanto-plasty) has been proposed in treatment of peri-implantitis.^73,74 The implanto-plasty technique involves the use of rotary instruments to smooth the exposed implant surfaces in order to reduce formation of plaque on the implant surface and to facilitate its removal.⁷³ The use of proper burs with coolant is of paramount importance for efficient cutting to reduce clinical time and to avoid excess heat generation that can damage the peri-implant tissue.⁷⁴ Romeo and colleagues⁷³ studied peri-implantitis lesions in 19 patients with 38 implants. The treatment involved systemic antibiotics (Amoxicillin for 8 days) with full-mouth disinfection. Nine patients were treated with resective surgery only and ten with resective surgery and implanto-plasty. Marginal bone levels were measured radiographically at 1, 2 and 3 years after surgery. The resective method combined with implanto-plasty was found to be more effective than the resective method alone. Consequently, it is not unreasonable to conclude that resective surgery coupled with implanto-plasty could have a positive influence on the survival rates of rough-surface implants affected by peri-implantitis, as well as on clinical peri-implant parameters such as BoP, PPD and suppuration.⁷³

It is important to remember that the resective approach is indicated when the regenerative treatment is not the treatment of choice.³² For instance, in horizontal bone loss where the regenerative approach may not be a rational option. However, this surgical approach may be used in a non-aesthetic zone as tissue recession is most likely to follow.

Regenerative approach (use of grafting materials with or without membrane): In general, the regenerative approach consists of flap elevation, mechanical root debridement and placement of a graft material, either alone or combined with a membrane. The membrane protects the graft material and provides a confined space for formation of the desired tissues. When the membrane is used without a graft material, the surgical method is known as guided tissue regeneration (GTR). Guided tissue regeneration (GTR) was initially used for treatment of periodontal disease to hinder epithelial and connective tissue migration into the surgical area but allowing cells from periodontal ligament (PL) and bone to repopulate the root surface after its debridement,^75,76,77,78 therefore new cementum, PL and alveolar bone are regenerated. The GTR concept is based on the hypothesis that the cell type which has the potential to colonize the exposed root surface at the periodontal healing site will dictate the nature of the resultant attachment or repair.⁷⁵ Thus, if epithelial cells reach the surgical site and repopulate the exposed root surface, a long junctional epithelium will form. However, if the perivascular cells of the alveolar bone, as well as cells from PL, repopulate the surgical site, new bone, cementum and PL will be created.^76,77,78 When the main goal of the surgical process is to regenerate new bone, the procedure is known as guided bone regeneration (GBR). This technique has been further applied to encourage bone formation on exposed surfaces of titanium implants in animal⁷⁹ and human studies.⁸⁰

The membrane used can be made of resorbable material, such as collagen membrane, for example (Bio-Gide®), or non-resorbable, such as expanded polytetrafluoroethylene (ePTFE). By the use of resorbable membrane the second surgical intervention needed to remove the membrane is avoided. However, resorbable membranes may be associated with more signs of post-surgical inflammation than non-resorbable ones.⁸¹ Studies comparing the use of resorbable and non-resorbable membranes indicated that both types had a comparable clinical effectiveness.^81,82 However, complications such as membrane exposure is a real problem which can have a detrimental impact on the treatment outcome.^83,84 The exposed membranes should be removed immediately because, if it is left in situ, the amount of bone gain will be negatively affected.

In treatment of peri-implantitis, the use of membrane is usually combined with graft materials. The objective here is to regenerate new bone, reduce PPD, gain of CAL and re-osseointegration of the decontaminated implant surface.⁸⁵ The use of grafting material with or without a membrane has been used extensively in the treatment of peri-implantitis, with a short-term follow-up with a promising outcome. As the exposure of the membrane is a problem that adversely affects the treatment outcomes, the use of graft material alone appears to be an effective alternative to the use of membrane and the combination of graft materials and the membrane is not always an ideal treatment option.² Nevertheless, Hürzeler et al^86,87 reported no significant difference in bone fill between the use of membrane alone and when the membrane was used with a graft material. However, according to these two studies, the combination of membrane and graft materials led to a greater amount of re-osseointegration than debridement alone (with an air-powder abrasive), or when debridement combined with membrane or graft materials. It is important to note that the findings of Hürzeler et al^86,87 were based on animal studies (seven beagle dogs) in which the peri-implantitis was induced by ligature applications for 3 months.^86,87

In another study in dogs,⁸⁸ no statistically significant differences in bone fill in the treatment of ligature-induced peri-implantitis were found when the use of membrane, bone graft, or a combination of the two methods, were compared. The three treatment options performed better and gained more bone fill than debridement alone. Accordingly, it was concluded that the three treatment techniques can improve the bone fill in defects caused by experimentally induced peri-implantitis in dogs.⁸⁸

The clinical study by Schwartz et al⁸⁹ demonstrated that treatment of moderate peri-implantitis with either nano-crystalline hydroxyapatite (Ostim®) or Bio-Oss®, in combination with the use of collagen membrane, provided clinically significant improvements in clinical parameters, such as PPD and CAL gains following 6 months of non-submerged healing. The two year results of the same clinical study⁹⁰ once more demonstrated that both treatment modalities were effective in providing clinically significant reductions of PPD and gains in CAL. However, the combination use of Bio-Oss® and collagen membrane seemed to correlate with greater improvements in those clinical parameters and hence were associated with greater predictability and enhanced healing outcome.

It may be concluded that the routine use of the membrane should be judgementally implemented⁸³ and the use of the membrane with graft material may not always be required, as there is no strong evidence to support its advantage.⁹¹ However, the use of graft material without a membrane may be considered when the graft material can be retained within the bony defect, such as in a circumferential bone defect, ie a 4-wall bony defect (Figures 7 and 8). The use of the membrane may be employed when the bony defect morphology does not retain the graft material, ie a 2-wall bony defect. However, long-term, well-controlled randomized clinical studies are required.⁸⁵ A summary of different treatment options for peri-implant disease, which is suggested by Lang and colleagues,³² is displayed in Table 3.

In general, it may be proposed that each peri-implantitis case should be evaluated clinically and radiographically in a similar manner, as in the treatment of periodontal disease. Oral hygiene should be observed and regular check-ups should be scheduled. In addition, a decision on how to handle the case can be made and which treatment modality should be considered and carried out. Moreover, the following points may be suggested as a general approach:

Following any treatment protocol, a follow-up period is essential in order to monitor oral hygiene and help stop and/or discover in time any further deterioration.