Infiltration of salivary proteins into dentin during erosive processes.

Objective: Ultrastructural analyses showed that during erosion under oral cavity conditions, dentin is infiltrated by a substrate morphologically similar to salivary proteins. This in-situ study aimed to investigate the presence of salivary proteins in demineralized dentin.

Methods: Bovine dentin specimens were attached to individual maxillary splints (n = 1 per subject and condition) and worn intraorally by four subjects for 1 min. During intraoral exposure, the subjects rinsed with 10 ml of either sterile water or 1 % citric acid. Additional specimens were eroded in-vitro as controls (n = 2). The specimens were then fixed, embedded in acrylic resin, and ultrathin sections were prepared. The salivary protein lysozyme was labelled with immunogold staining and examined using transmission electron microscopy.

Results: Lysozyme was absent in the in-vitro controls but was detected on the dentin surface after rinsing with water, indicating its role in the initial pellicle formation on dentin. After rinsing with citric acid, lysozyme infiltrated deeper layers of the dentin.

Conclusions: These findings support the initial morphological observations that lysozyme, representing other salivary proteins, is deposited in demineralized dentin during erosion with citric acid.

Clinical Significance: Infiltration of salivary proteins into dentin during erosive processes can be a factor to consider in remineralization approaches under oral cavity conditions.