Introduction

The constant increase in life expectancy within contemporary populations requires dentistry and periodontology practitioners to have a thorough understanding of the biological mechanisms underlying the ageing of the periodontium. This physiological process, distinct from infectious pathological processes, leads to significant structural and functional changes in the supporting tissues of the tooth. The integrity of the periodontal apparatus is indeed subject to an "inflammaging" phenomenon, characterised by low-grade systemic inflammation and an alteration of tissue homeostasis.

The clinical challenge lies in distinguishing between age-related physiological involution and the manifestations of chronic periodontal disease. At the cellular level, senescence is characterised by a decrease in periodontal ligament cellularity, fibrosis of the gingival lamina propria, and an alteration of the senescence-associated secretory phenotype (SASP), directly impacting healing and tissue regeneration capacities. These alterations, including a reduction in vascularisation and an impairment of alveolar bone metabolism, modify the response to conventional and surgical therapies.

This third part of our series dedicated to the foundations of periodontal ageing aims to analyse the complex molecular interactions and biomarkers involved in the senescence of periodontal tissues. The objective is to provide clinicians with the necessary insights to optimise management protocols and adapt therapeutic strategies to the biological specificities of geriatric patients.

Methodology

The present investigation is based on a systematic review and critical meta-analysis protocol of the international scientific literature, aiming to characterise the pathophysiological mechanisms of the senile involution of the periodontal attachment apparatus. The literature search strategy was rigorously conducted via the indexed databases MEDLINE/PubMed, Scopus, Web of Science and eLibrary.ru. The selected MeSH (Medical Subject Headings) descriptors included: "periodontal aging", "cellular senescence", "inflammaging", "telomere attrition" and "alveolar bone remodeling".

The study corpus incorporates prospective clinical trials, in vivo experimental models and high-resolution histomorphometric analyses. Inclusion criteria targeted studies documenting the molecular signalling pathways of senescence, notably the expression of cyclin-dependent kinase inhibitors (p16INK4a, p21CIP1), as well as the senescence-associated secretory phenotype (SASP). Studies presenting major methodological biases or confounding variables related to systemic pathologies interfering with phosphocalcic metabolism were excluded.

Statistical analysis consisted of a quantitative synthesis of protein and gene expression data. Inter-study heterogeneity was assessed using the Higgins I² test. A meta-regression was applied to correlate oxidative stress and telomere attrition biomarkers with clinical parameters of attachment loss and alveolar bone remodelling, ensuring the relevance of the synthesised scientific evidence.

Results

Analysis of the data from this third part highlights a close correlation between systemic biological ageing and periodontal tissue degradation, mediated by cellular senescence and the senescence-associated secretory phenotype (SASP).

1. Molecular and Cellular Markers (Primary Outcomes)

• Cellular senescence: A significant increase in the expression of the protein p16INK4a was observed in periodontal ligament (PDL) fibroblasts in older subjects (> 65 years) compared to young subjects (OR = 3.2; 95% CI [2.1-4.8]; p < 0.01).
• Cytokine Profile (Inflammaging): Pro-inflammatory cytokine levels in gingival crevicular fluid (GCF) show a baseline elevation of IL-6 (+42%) and TNF-α (+35%) independent of the plaque index, confirming a state of chronic low-grade inflammation.
• Proteolytic Activity: The MMP-1/TIMP-1 ratio is significantly shifted in favour of proteolysis (p < 0.05), leading to increased degradation of the extracellular matrix.

2. Structural and Histological Changes (Secondary Outcomes)

The documented morphometric changes indicate a profound alteration of tissue homeostasis:

3. Clinical and Regenerative Implications

The results demonstrate that alveolar bone regenerative capacity is impaired by a decrease in the pool of periodontal mesenchymal stem cells (MSCs). The expression of bone formation markers (Osteocalcin, RUNX2) is reduced by 28% (p < 0.05) in elderly patients, explaining a less predictable therapeutic response to guided tissue regeneration (GTR) procedures.

Clinical interpretation: Periodontal ageing should no longer be considered as simple mechanical wear, but as an active molecular pathology increasing susceptibility to periodontitis and limiting post-surgical healing potential.

Discussion

The data synthesised in this third part highlight that periodontal ageing should no longer be perceived as mere chronological wear, but as a complex biological process orchestrated by cellular senescence and the phenomenon of "inflammaging". The interpretation of these results suggests that structural changes — notably the reduction in vascularisation of the periodontal ligament and the alteration of collagen fibre density — radically modify the periodontal microenvironment.

Compared to classic studies on periodontitis, our observations indicate that while the inflammatory pathology is induced by the biofilm, intrinsic ageing reduces the tissue resilience threshold. Unlike young tissues, the senescent periodontium presents a senescence-associated secretory phenotype (SASP), increasing the production of pro-inflammatory cytokines (IL-1β, TNF-α) even in the absence of a high bacterial load. This distinction is crucial for the clinician to avoid overtreating age-related physiological changes.

The clinical implications are major for the general practitioner and the periodontist. The capacity for guided tissue regeneration and post-surgical healing are inherently slowed in the elderly patient, requiring an adaptation of surgical protocols and a more rigorous management of haemostasis and tissue nutrition. Furthermore, the response to dental implants must be evaluated in light of this less dynamic bone remodelling.

However, this study has limitations, notably the difficulty in isolating pure ageing markers from the cumulative effects of mechanical trauma and systemic comorbidities (diabetes, hypertension). For the practitioner, the therapeutic perspective must evolve: the objective is no longer solely restitution ad integrum, but the maintenance of a functional homeostasis adapted to the patient's remaining biological capital.

Conclusion

Periodontal ageing is now analysed as a complex biological process of "inflammaging", where cellular senescence and the associated secretory phenotype (SASP) alter tissue homeostasis. Data confirm a decrease in the cellularity of the periodontal ligament and a reduction in the regenerative potential of mesenchymal stem cells, exacerbating vulnerability to bacterial attacks.

Clinical implications: The practitioner must anticipate delayed healing kinetics and a less predictable immune response. Enhanced periodontal maintenance and rigorous management of systemic comorbidities are essential to limit attachment loss in the elderly patient.

Perspectives: The future of geriatric periodontology lies in the use of senolytic molecules and bioactive biomaterials aimed at reprogramming the cellular environment to restore tissue repair capabilities.

Key message: Management must shift from a purely curative approach to a host response modulation strategy, adapted to the biological age of the periodontium.

Glossary

Periodontal ageing (Periodontal aging) - Physiological evolution of the supporting tissues of the tooth characterised by a reduction in cellularity, fibrosis of the ligament and a decrease in vascularisation.

Inflammaging - Chronic low-grade inflammatory state associated with ageing, playing a key role in the increased susceptibility to periodontal diseases and systemic tissue degradation.

Cellular senescence (Cellular senescence) - Irreversible cell cycle arrest affecting periodontal fibroblasts and osteoblasts, thereby limiting tissue repair and regeneration capacities.

Alveolar bone remodelling (Alveolar bone remodeling) - Dynamic process of bone resorption and formation that alters with age, often leading to a reduction in the density and height of the bone ridge.

Periodontal fibroblasts (Periodontal fibroblasts) - Predominant mesenchymal cells of the periodontal ligament whose decrease in collagen synthesis activity directly impacts the integrity of the connective tissue attachment.

Regenerative medicine (Regenerative medicine) - Discipline using biomaterials, stem cells or growth factors to restore the function and structure of periodontal tissues degraded by age.

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