Type I collagen degradation end-products and related matrix metalloproteinases (MMPs) were examined aiming to detect potential markers of periodontitis in saliva, with high sensitivity and specificity.

The salivary concentrations of MMP-8, MMP-9 and MMP-13, tartrate-resistant acid phosphatase serum type 5b, C-terminal cross-linked telopeptide of type I collagen (CTx), N-terminal cross-linked telopeptide of type I collagen (NTx) and cross-linked carboxyterminal telopeptide of type I collagen were analysed in 230 subjects. Oral health examination included panoramic radiography.

The concentrations of MMP-8, MMP-9 and MMP-13 in saliva were higher in subjects with generalized periodontitis than in controls. Of the tested salivary markers, MMP-8 was the only marker capable of differentiating subjects with severe alveolar bone loss from those with slight bone loss (p < 0.001). The association between the salivary MMP-8 levels and periodontitis remained significant after the adjustment with age, gender and smoking. In addition, significant correlations were found between the tested markers and periodontal parameters.

Enzymes and end-products of type I collagen degradation have different associations with each other and with periodontal status that may reflect their roles in the cascade leading to alveolar bone loss. MMP-8 is a strong biomarker candidate for detecting alveolar bone destruction.