The proteome of the human parotid gland secretion in elderly with and without root caries

Saliva is important for oral health, including the prevention of dental decay. The purpose of the present work was to indicate whether the parotid gland has altered function in the elderly, particularly in terms of proteins secreted, and whether its functional status could be associated with the presence of root caries.

Ductal parotid gland secretion was obtained from 51 individuals: 21 elderly with carious roots (Patients), 20 elderly (Controls), and 10 adults (Young) without root caries. Pooled aliquots were analyzed by liquid chromatography/tandem mass spectrometry to yield lists of major proteins present in the three groups.

Approximately 200 unique proteins were detected, of which 73 were identified repeatedly with high confidence and therefore included in the comparison. Some of the differences observed, when comparing Patients with respectively elderly Controls and the Young, resembled changes found in patients with Sjogren's syndrome, a condition associated with dental decay. Other changes involved proteins that are likely to impact on the oral microbiota, such as the absence of dermcidin and the presence of collagen in Patients. Cystatin S, a putative indicator of caries, was present at a higher level in Patients.

Parotid function tends to change upon aging, with possible consequences as to caries activity. However, analyses of individual samples revealed considerable variations in protein patterns.