Cold plasma: a double lever against peri-implantitis

The management of peri-implantitis presents the practitioner with a dual clinical challenge: eradicating a complex bacterial biofilm and restoring osseointegration on a degraded implant surface. Faced with the limitations of conventional decontamination methods, cold atmospheric plasma (CAP) is generating increasing interest. This technology is being studied for its direct antimicrobial action and its ability to modify the physico-chemical properties of implant surfaces.

The objective of this scoping review, conducted according to the PRISMA-ScR protocol, is to synthesize evidence from 77 preclinical studies to evaluate the biological relevance of CAP. The authors test the hypothesis that CAP can act simultaneously as a decontamination agent and as a promoter of bone regeneration. By improving implant hydrophilicity and stimulating the osteoblastic response, this technology could significantly increase bone-to-implant contact (BIC), thus providing a rational basis for a new adjuvant approach in the treatment of peri-implant infections.

Review methodology

This study is a scoping review conducted in accordance with PRISMA-ScR guidelines. The objective was to synthesise current evidence regarding the application of cold atmospheric plasma (CAP) in the treatment of peri-implantitis. To achieve this, the authors performed an exhaustive search of the PubMed, Scopus, Web of Science, and Google Scholar databases.

The final corpus includes 77 studies selected according to rigorous criteria:

• Nature of the models: In vitro, ex vivo studies and animal models (human clinical data being still limited).
• Thematic axes: 31 studies focus on the decontamination of implant surfaces and 46 deal with results related to osseointegration.
• Selection criteria: Inclusion of models reflecting the key biological components of peri-implantitis, despite the absence of standardized models.

The methodological analysis highlights significant heterogeneity in the experimental parameters evaluated: types of plasma devices, gas composition, exposure protocols, implant materials, and biological models. The evaluation focused on the ability of CAP to modulate surface hydrophilicity, osteoblast response, and bone-to-implant contact (BIC).

Analysis of 77 studies: Decontamination and Osseointegration

This literature review compiled data from 77 studies selected according to PRISMA-ScR criteria. The authors segmented the evidence into two major axes to evaluate the impact of cold atmospheric plasma (CAP) on the biological components of peri-implantitis.

The overall results highlight a consistent efficacy of CAP, although the protocols (gas composition, exposure duration, devices) show marked heterogeneity.

Antibacterial efficacy and surface modifications

Of the 31 studies dedicated to decontamination, CAP demonstrated a systematic antibacterial effect. Beyond the reduction of the bacterial load, qualitative observations highlight a radical transformation of the implant surface properties:

• Hydrophilicity enhancement: Plasma treatment reduces the contact angle, promoting the spreading of biological fluids.
• Surface cleaning: Effective elimination of organic contaminants without altering the macro-geometry of the implant.

Impact on bone regeneration (Preclinical outcomes)

The 46 studies on osseointegration reveal that CAP acts as a biological catalyst. Preclinical data (in vitro and animal models) show:

• Cellular response: Increased osteoblast adhesion and proliferation on treated surfaces.
• Bone-Implant Contact (BIC): Animal models report an increase in the BIC rate, suggesting faster and denser integration.

It is, however, crucial to note that these results, although statistically significant within their respective frameworks, originate from models that do not always faithfully reproduce the clinical complexity of human peri-implantitis. Biological plausibility is established, but clinical superiority remains to be validated by randomised controlled trials.

Analysis of results and biological plausibility

This PRISMA-ScR review of 77 studies clarifies the role of cold atmospheric plasma (CAP) as an implant rescue tool. The clinical interest lies in its dual action: while 31 studies confirm its effectiveness against biofilm, 46 others highlight an improvement in osseointegration processes. Unlike conventional chemical decontaminants, CAP modifies surface energy, making the implant ultra-hydrophilic, which directly promotes osteoblastic adhesion and increases bone-to-implant contact (BIC) in preclinical settings.

Evidence still confined to the preclinical stage

However, caution remains necessary in the practice. The study reveals massive heterogeneity in the devices and gases used, making it difficult to establish a universal protocol. Furthermore, most of the data comes from in vitro or animal models that only partially simulate human pathology. While the biological plausibility is solid, the actual clinical efficacy remains to be demonstrated by large-scale randomized controlled trials.

Summary of results

This systematic review of 77 studies (31 dedicated to decontamination and 46 to osseointegration) confirms the potential of cold atmospheric plasma (CAP) as a therapeutic adjuvant. Preclinical data demonstrate a consistent bactericidal action coupled with a significant increase in surface hydrophilicity, promoting osteoblastic response and bone-to-implant contact (BIC).

In concrete terms, for the practitioner:

• Surface optimization: Consider CAP as a high-performance biological option for decontaminating implant threads while increasing their surface energy.
• Double benefit: Rely on this technology to act simultaneously on reducing the bacterial load and stimulating re-osseointegration.
• Protocol caution: In the absence of standardized clinical protocols, the use of CAP remains an adjuvant strategy whose exposure parameters (duration, gas) must still be refined for each clinical situation.

Technical lexicon of the study

Peri-implantitis: Inflammatory pathology of infectious origin (associated with biofilm) causing progressive marginal bone loss around dental implants in function.

Cold Atmospheric Plasma (CAP): Cold plasma produced at atmospheric pressure, used in dentistry for its antimicrobial properties and its ability to modify the surface energy of biomaterials without thermal alteration.

Decontamination: Procedure aimed at eliminating bacterial biofilm and toxins from the implant surface to stop the progression of peri-implant infection.

Osseointegration: Process of restoring a direct structural and functional connection between the bone and the implant surface, evaluated here by bone-to-implant contact (BIC).

Hydrophilicity: Surface property increasing affinity for liquids, enhanced by CAP treatment, thus promoting osteoblast adhesion and response.

Bone-to-implant contact (BIC): Histomorphometric parameter measuring the percentage of the implant surface in direct contact with the newly formed bone.

Biofilm: Complex aggregate of microorganisms adhering to the implant surface, constituting the primary target of plasma decontamination strategies.

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