Salivary Biomarkers in Different Implant-Supported Prostheses

Structural Versus Adaptive Salivary Signatures Across Implant-Supported Prosthetic Configurations: A Cross-Sectional Comparison of sIgA, MMP-8, and MMP-9

This observational cross-sectional study compared salivary biomarkers among adults with different types of implant-supported prosthetic rehabilitation and periodontally healthy adults with natural teeth. A total of 107 participants were included in four groups: periodontally healthy individuals with natural teeth, patients with implant-supported partial fixed prostheses and remaining natural teeth, patients with full-arch fixed implant-supported prostheses, and patients with implant-retained overdentures.

The study measured three biomarkers in unstimulated whole saliva: secretory immunoglobulin A (sIgA), matrix metalloproteinase-8 (MMP-8), and matrix metalloproteinase-9 (MMP-9). These biomarkers are related to oral immune responses and tissue remodeling.

The main aim was to determine whether salivary biomarker levels differed according to dentition status and type of implant-supported prosthesis. The study also examined relationships between these biomarkers and clinical parameters, including probing depth. No experimental treatment or intervention was assigned by the study protocol.

This single-center, observational, cross-sectional study evaluated salivary biomarker profiles across different dentition statuses and implant-supported prosthetic configurations.

Participants were classified into four groups according to dentition status and type of prosthetic rehabilitation: periodontally healthy, fully dentate individuals without implants; patients with implant-supported partial fixed prostheses and remaining natural teeth; patients rehabilitated with full-arch fixed implant-supported prostheses; and patients rehabilitated with implant-retained overdentures.

Clinical examination included periodontal and peri-implant probing depth measurements. The numbers of natural teeth and dental implants were also recorded. Unstimulated whole saliva was collected under standardized conditions and analyzed for secretory immunoglobulin A (sIgA), matrix metalloproteinase-8 (MMP-8), and matrix metalloproteinase-9 (MMP-9) using enzyme-linked immunosorbent assay (ELISA).

The primary objective was to compare salivary concentrations of sIgA, MMP-8, and MMP-9 among the four groups. Secondary objectives were to evaluate associations between biomarker concentrations and clinical parameters and to explore the ability of these biomarkers to distinguish among different dentition statuses and prosthetic configurations.

Because the study was observational, participants were not assigned to any treatment, intervention, or prosthetic rehabilitation under the study protocol. All prosthetic rehabilitations were in place before study enrollment.

Inclusion Criteria:

• Age 18 years or older.
• Ability and willingness to provide written informed consent.
• For the healthy dentate group: fully dentate individuals without dental implants who were systemically and periodontally healthy, with probing depths of 3 mm or less at all sites and full-mouth bleeding on probing below 10%.
• For the implant groups: presence of an implant-supported partial fixed prosthesis, full-arch fixed implant-supported prosthesis, or implant-retained overdenture with osseointegrated implants restored with a definitive prosthesis in function for at least 6 months.

Exclusion Criteria:

• Antibiotic use within the preceding 6 months.
• Periodontal therapy within the preceding 6 months.
• Systemic conditions known to affect periodontal or immune status, including diabetes mellitus, cardiovascular disease, rheumatoid arthritis, systemic lupus erythematosus, or inflammatory bowel disease.
• Systemic infectious diseases, including tuberculosis, hepatitis, or human immunodeficiency virus infection.
• Mucocutaneous diseases affecting the oral mucosa, including lichen planus, pemphigus vulgaris, or chronic ulcerative stomatitis.
• Ongoing systemic corticosteroid, immunosuppressant, or biologic therapy.
• Pregnancy or lactation.