Aggregated inflammatory indices, such as NLR, PLR, MLR, SII, SIRI, and AISI/PIV, are attracting increasing attention because they allow inflammation to be viewed not through a single marker, but through the relationships between different elements of the immune response. In peri-implantitis, this may be particularly relevant, as the disease develops at the intersection of biofilm, host response, systemic factors, and local conditions around the implant. At the same time, these indices are not ready-made diagnostic tests. Their value depends on clinical context, and their use in peri-implantitis requires further validation, standardization, and cautious interpretation.
In medicine, there is a growing search for simple, accessible, and reproducible tools that may help assess systemic inflammation. The aim is not only to identify acute infection or a strong inflammatory reaction, but also to capture more subtle, chronic processes that may influence disease progression, tissue healing, and treatment prognosis. In this context, indices derived from routine blood count parameters are of particular interest.
Aggregated inflammatory indices are created by mathematically combining at least two laboratory parameters. Most often, they use neutrophil, lymphocyte, monocyte, and platelet counts. Their basic idea is straightforward: a single parameter may show only one fragment of the inflammatory reaction, while relationships between different immune cell populations may better reflect the overall immunological balance of the body.
The most commonly discussed indices include NLR, the neutrophil-to-lymphocyte ratio; PLR, the platelet-to-lymphocyte ratio; MLR, the monocyte-to-lymphocyte ratio; as well as more complex indices such as SII, SIRI, and AISI/PIV. In the PERI-EDU materials, they are described as blood count-derived indices whose aim is to provide a synthetic assessment of the systemic inflammatory and immune response by simultaneously taking into account pro-inflammatory and regulatory components of the immune system.
From the perspective of implant dentistry, this approach is interesting for several reasons. Peri-implantitis is a local disease, but it does not necessarily have to be only a local problem. Bacterial biofilm initiates the inflammatory response around the implant, but the course of the disease depends on how the patient’s body responds to this stimulus. If the immune response is excessive, chronic, or insufficiently resolved, local inflammation may lead to faster bone destruction and a less favorable prognosis.
In this sense, aggregated inflammatory indices may be seen as an attempt to capture the systemic background in which peri-implantitis develops. They do not directly show the condition of the bone around the implant or describe the implant surface, but they may provide information on whether the patient’s organism is functioning in a state of increased inflammatory activation. For clinicians, this may be potentially relevant, especially when the local clinical picture does not fully explain the dynamics of the disease.
One of the greatest advantages of CBC-derived indices is their accessibility. Because they are calculated from routine blood count parameters, they do not require complicated, expensive, or difficult-to-access laboratory procedures. For the patient, this means low invasiveness and minimal burden. For the clinician, it means the possibility of repeating measurements over time, comparing results, and potentially monitoring changes in the broader inflammatory profile.
This reproducibility is particularly important in chronic diseases. Peri-implantitis is rarely a single event. It is often a process that develops over time, may include periods of stabilization and progression, and requires supportive care after treatment. In this context, a single laboratory result has limited significance, but observing trends may prove more valuable in the future — especially when combined with clinical and radiological parameters.
Another potential advantage is improved patient stratification. Materials discussing the advantages and limitations of inflammatory indices emphasize that these tools may be particularly interesting in patients with systemic diseases such as diabetes, cardiovascular disease, or metabolic syndrome. In such patients, the inflammatory response may be more pronounced and may promote faster destruction of peri-implant tissues.
For clinicians, this is an important perspective. Implantologists often see patients who do not fit into a simple “good” or “poor” candidate category. A patient may have moderate hygiene problems, a well-designed restoration, and at the same time poorly controlled diabetes, obesity, a history of periodontitis, or chronic inflammatory burden. In such cases, local assessment remains the foundation, but it does not exhaust the entire risk profile.
Inflammatory indices may in the future help answer the question of whether a patient requires standard follow-up or more intensive monitoring. They could also support decisions regarding recall intervals, the need for cooperation with the patient’s physician, assessment of anti-inflammatory treatment response, or identification of patients in whom local inflammation may have greater destructive potential. At present, however, this remains primarily a research direction, not a ready clinical algorithm.
The greatest limitation of aggregated inflammatory indices is their nonspecificity. An elevated index does not automatically mean that the cause is peri-implantitis. NLR, PLR, SII, or SIRI values may change in acute infection, autoimmune disease, cancer, trauma, stress, medication use, metabolic disorders, and even depending on age or general health status. The same result may therefore mean very different things in different patients.
For this reason, interpreting these indices without clinical context would be risky. An elevated index should not lead to an automatic diagnosis of peri-implantitis, just as a normal result should not reassure the clinician if clinical and radiological examination indicates active disease around the implant. In implant dentistry, the assessment of tissues, probing, bleeding on probing, pocket depth, bone imaging, prosthetic evaluation, and patient history cannot be replaced by a single laboratory parameter.
A second important limitation is the lack of standardized diagnostic cut-off values specific to peri-implantitis. In many areas of medicine, inflammatory indices are studied as prognostic or supportive markers, but transferring them into implant dentistry requires caution. It is not yet clear which values should raise concern in the context of peri-implant tissue inflammation, whether the same cut-offs should be used in healthy patients and in those with chronic diseases, or how changes in indices over time should be interpreted.
A third issue is the limitation of available scientific data. Many studies on inflammatory markers and indices are observational or cross-sectional. They often differ in definitions of peri-implantitis, patient inclusion criteria, population characteristics, diagnostic methods, and control of confounding factors. This makes it difficult to draw simple cause-and-effect conclusions. PERI-EDU materials emphasize precisely this heterogeneity of available studies and the need for further validation of these tools.
In practice, this means that inflammatory indices should be treated as one element of a larger puzzle. They may be valuable, but only when interpreted together with other data. The clinician should know whether the patient has an active infection, autoimmune disease, diabetes, cancer, uses immunomodulatory drugs, smokes, has obesity, metabolic syndrome, or has recently undergone surgery. Without this information, an inflammatory index may easily be overestimated or misinterpreted.
This is why an integrated approach is so important in the PERI-EDU project. The aim is not to find one number that will replace clinical diagnostics. The aim is to examine whether combining clinical, radiological, general medical, and laboratory data can improve our understanding of the disease. If peri-implantitis is a multifactorial process, then its assessment should also be multidimensional.
This way of thinking has important educational value. In teaching implant dentistry, it is easy to focus on visible elements: the implant, bone, soft tissues, prosthetic restoration, and radiological image. These elements are fundamental and cannot be omitted. However, contemporary education should also show that behind this clinical image lies the patient’s biology: inflammation, immune response, chronic diseases, metabolism, and healing capacity.
For students and young clinicians, aggregated inflammatory indices may therefore be not only potential diagnostic tools, but also useful models of thinking. They show that disease cannot always be described by a single result. They also show that interpreting data requires understanding mechanisms, not only reading laboratory reference ranges. In peri-implantitis, it is particularly important to combine information from different levels: from biofilm and local tissues to the patient’s systemic profile.
For the practicing clinician, the most important conclusion is this: aggregated inflammatory indices may be interesting, but they should not be treated as shortcuts. Their potential lies in complementing clinical assessment, not replacing it. They may help ask better questions about the patient, but they do not yet provide definitive answers on their own.
In the future, after appropriate validation, blood count-derived indices could find application in selected clinical situations. They could support assessment of patients with chronic diseases, monitoring of treatment response, identification of individuals at increased risk of progression, or the design of more individualized supportive care protocols. This, however, requires prospective studies, methodological standardization, definition of reference values, and evaluation of usefulness in real implant practice.
Caution does not weaken the value of these tools. On the contrary, it increases their credibility. In medicine, solutions that promise a simple answer to a complex problem are especially risky. Peri-implantitis is precisely such a complex problem: it involves biofilm, tissues, the implant, prosthetics, immunology, systemic diseases, and patient behavior. If inflammatory indices are to be useful, they must be incorporated into this complexity, not presented as a simplification of it.
Aggregated inflammatory indices in peri-implantitis should therefore be regarded as a promising direction, but with clearly defined limits. Their advantages include accessibility, low cost, reproducibility, and the possibility of capturing the systemic dimension of the inflammatory response. Their limitations include lack of specificity, lack of peri-implantitis-specific cut-off values, and the need for interpretation in the context of the whole patient.
PERI-EDU develops precisely this cautious, integrated perspective. The goal is not to replace classical diagnostics with a new index, but to broaden the way we think about the implant patient. If we want to better predict the course of peri-implantitis, we need to learn how to connect what we see around the implant with what is happening in the patient’s organism. Aggregated inflammatory indices may be one of the tools supporting this direction — provided they are used responsibly, critically, and on the basis of further research.