PERI-EDU University Education
Peri-implantitis produces an intense local immune lesion. Microbial exposure activates innate and adaptive responses, inflammatory mediators contribute to connective-tissue injury, and osteoclasts remove supporting bone. These local mechanisms are well supported. Claims about systemic consequences require a separate and more cautious level of evidence.
The lesion develops within a peri-implant tissue compartment that differs anatomically from the periodontal attachment around a natural tooth. Its biological course reflects interactions among immune-cell recruitment, cytokine signalling, connective-tissue degradation, osteoclast activation and the local conditions that support persistent biofilm exposure.
The peri-implant inflammatory lesion
Peri-implant tissues differ from the periodontal attachment apparatus. Connective-tissue fibres do not insert into the implant surface, and the supracrestal zone has a different vascular arrangement. These anatomical features do not cause peri-implantitis, but they influence how inflammation can extend towards the supporting bone.
Histological studies describe peri-implantitis lesions rich in plasma cells and lymphocytes, with prominent neutrophils and macrophages. Lesions can extend apically and may occupy a larger area than corresponding periodontitis lesions. Greater lesion size indicates a substantial local inflammatory burden, but it cannot by itself demonstrate systemic exposure.
Innate and adaptive immunity interact
| Cell population | Role in the lesion | Interpretation |
|---|---|---|
| Neutrophils | Rapid antimicrobial response, phagocytosis and release of enzymes or reactive mediators. | Their prominence reflects an active microbial challenge. |
| Macrophages | Microbial recognition, phagocytosis and amplification of cytokine signalling. | Phenotype and function can vary across the lesion and disease stage. |
| T lymphocytes | Coordinate cellular immune responses and influence inflammatory or regulatory pathways. | Their effect depends on local activation and cytokine context. |
| B lymphocytes and plasma cells | Support humoral responses and antibody production in chronic lesions. | Their proportions increase in established peri-implantitis compared with mucositis. |
Innate and adaptive immunity should not be viewed as separate processes. Macrophage-derived signals shape lymphocyte responses, while lymphocyte mediators influence macrophage and osteoclast behaviour. The lesion functions as an interacting cellular network.
Inflammatory mediators
Interleukin-1 beta is frequently elevated in peri-implant mucositis and peri-implantitis compared with health. Values can overlap between mucositis and peri-implantitis, which limits its ability to classify disease stage. Tumour necrosis factor is also elevated at many diseased sites and supports a pro-inflammatory tissue environment.
Tissue studies suggest that interleukin-1 alpha can participate in osteoclast-activating networks. Interleukin-6 contributes to inflammatory signalling, while findings for interleukin-4, interleukin-10 and RANKL are less consistently discriminatory. A negative or overlapping marker is scientifically important because it limits the usefulness of a single-molecule diagnostic model.
Why one cytokine cannot define the lesion
Cytokines act through connected pathways. One mediator may influence endothelial activation, immune-cell recruitment, matrix degradation or osteoclastogenesis depending on its concentration, timing and target cell. A laboratory result captures only one point in a changing biological system.
A marker can show a statistically higher group mean while retaining substantial overlap between individual patients. Clinical use requires validated thresholds, reproducible sampling, acceptable sensitivity and specificity, and a defined decision that improves patient care.
Host-mediated tissue destruction
Bacteria initiate the challenge, while the host inflammatory response produces much of the structural damage. Pattern-recognition receptors detect microbial products and damaged tissue. Cytokines and chemokines recruit additional cells, while proteases and reactive mediators contribute to degradation of collagen and extracellular matrix.
Inflammatory signalling also changes bone remodelling. Osteoclasts arise from monocyte-macrophage lineage precursors. Their differentiation depends on macrophage colony-stimulating factor and RANKL, while osteoprotegerin can limit RANKL activity. Pro-inflammatory cytokines influence this axis directly and through stromal, immune and bone cells.
Why progression can accelerate
As supporting bone is lost, a larger area of rough implant surface becomes exposed within a sheltered defect. This anatomy retains biofilm and limits daily hygiene or closed professional debridement. Persistent microbial exposure sustains the inflammatory network, creating feedback between defect morphology and lesion activity.
Peri-implant crevicular fluid
Peri-implant crevicular fluid samples the local compartment next to the implant sulcus. It may contain cytokines, chemokines, matrix-degrading enzymes and mediators related to bone turnover. Its composition can provide information about inflammatory activity near the sampled site.
Interpretation depends heavily on technique. Strip position, collection duration, fluid volume, contamination, assay platform and the clinical case definition all influence results. Pooling samples from several sites may also dilute a focal active signal.
| Variable | Why it matters | Source of variation |
|---|---|---|
| Sampling site | A focal lesion can differ between surfaces of the same implant. | Pooling sites can dilute an active local signal. |
| Fluid volume | Inflamed sites often produce more exudate. | Concentration and total amount can support different conclusions. |
| Collection method | Strip placement and duration influence recovery. | Blood, saliva or plaque contamination can alter measured values. |
| Assay platform | Detection limits and antibody specificity determine performance. | Results from different assays may not be directly comparable. |
No local biomarker panel currently replaces bleeding, probing and radiographic comparison in routine diagnosis. A high concentration next to one implant also does not establish a systemic effect.
Systemic inflammatory associations
A 2023 systematic review reported higher circulating C-reactive protein, interleukin-6 and white blood cell counts in patients with peri-implantitis compared with controls. The CRP analysis showed very high heterogeneity. These findings support an association with systemic inflammatory burden but do not establish that peri-implantitis caused the circulating changes.
Confounding
Smoking, diabetes, obesity, periodontitis history and maintenance behaviour can influence both peri-implant disease and systemic inflammation. If studies do not measure and adjust for these determinants adequately, the apparent association may partly reflect shared risk.
Reverse causation
Systemic inflammatory or metabolic dysregulation may increase susceptibility to peri-implant disease. A single examination cannot determine whether the oral lesion preceded the systemic marker, followed it or developed in parallel.
Temporality and treatment evidence
A causal interpretation requires longitudinal evidence showing the sequence of events. It becomes stronger if treatment of peri-implantitis produces a reproducible change in systemic outcomes compared with an appropriate control, after adjustment for shared determinants and concurrent medical treatment.
An evidence ladder for communication
- Established: biofilm-associated inflammation creates a cell-rich local lesion and host-mediated supporting bone loss.
- Supported local association: selected crevicular-fluid mediators are higher in disease groups.
- Supported systemic association: some studies report higher circulating inflammatory markers in patients with peri-implantitis.
- Emerging hypothesis: mediator exchange and bidirectional oral-systemic effects are biologically plausible but require stronger causal evidence.
Clinical implications
Medical history remains essential. Record chronic diseases, medication use and current medical control because they influence procedural safety and healing. Coordinate care when diabetes, cardiovascular risk, immunosuppression or antiresorptive medication affects treatment planning.
Use local clinical and radiographic findings as the primary treatment indications. Current treatment endpoints include reduced bleeding and suppuration, improvement in pathological probing depths, arrest of further bone loss and restoration of maintainability. Do not promise that local therapy will treat a systemic disease.
Clinical and biological synthesis
- Peri-implantitis contains a dense lesion in which innate and adaptive immune responses interact.
- IL-1 beta, TNF and related networks support inflammation and osteoclast activation, but no single marker defines disease stage.
- Peri-implant crevicular fluid reflects a local compartment and is sensitive to collection and assay methods.
- Higher systemic inflammatory markers have been reported in peri-implantitis, but causality remains unproven.
- Patient communication should distinguish established local mechanisms from emerging systemic hypotheses.
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The extended PDF explains lesion anatomy, immune-cell functions, cytokine networks, osteoclast activation, local biomarker sampling and the interpretation of systemic associations.
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Selected references
- Berglundh T, Armitage G, Araujo MG, et al. Peri-implant diseases and conditions: consensus report of workgroup 4 of the 2017 World Workshop. Journal of Clinical Periodontology. 2018;45(Suppl 20):S286-S291. doi:10.1111/jcpe.12957.
- Schwarz F, Derks J, Monje A, Wang HL. Peri-implantitis. Journal of Clinical Periodontology. 2018;45(Suppl 20):S246-S266. doi:10.1111/jcpe.12954.
- Herrera D, Berglundh T, Schwarz F, et al. Prevention and treatment of peri-implant diseases: the EFP S3 level clinical practice guideline. Journal of Clinical Periodontology. 2023;50(Suppl 26):4-76. doi:10.1111/jcpe.13823.
- Yan Y, Orlandi M, Suvan J, et al. Association between peri-implantitis and systemic inflammation: a systematic review and meta-analysis. 2023. PubMed PMID:37691939.
- Lumbikananda S, et al. Oral fluid biomarkers for peri-implantitis: a scoping review. 2024. PubMed PMID:38065782.
- La Monaca G, et al. Biomarkers in peri-implant crevicular fluid of healthy implants and untreated peri-implant disease: a systematic review and meta-analysis. 2025. PubMed PMID:40101934.
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This educational material does not replace individual clinical assessment, laboratory interpretation or medical consultation.
This work was co-funded by the European Union under grant agreement No. 2024-1-PL01-KA220-HED-000251208. Views and opinions expressed are those of the author(s) only and do not necessarily reflect those of the European Union or the Foundation for the Development of the Education System (FRSE). Neither the European Union nor FRSE can be held responsible for them.