Pathology · patient case question
How does saliva contribute to enamel remineralisation?
Patient case: The mouth that will not stay wet
demo: 54-year-old female
chief: Burning, sticky mouth for the past eight months; food gets caught and she wakes at night to sip water.
history: Hashimoto thyroiditis. Her rheumatologist ordered an autoantibody panel after she reported gritty, burning eyes.
meds: Levothyroxine 75 mcg daily. Amitriptyline 25 mcg at night for chronic tension headache.
findings: Anti-SSA (Ro) strongly positive. Salivary pooling is absent; the mucosa is dry and the tongue is fissured with papillary atrophy. Cracking and erythema at both commissures. Two new cervical lesions since her last visit a year ago.
Show answer and explanation
Correct answer: A. It supplies calcium and phosphate ions that redeposit into the enamel lattice
- A. Correct. Saliva is supersaturated with calcium and phosphate. When pH recovers above the critical value of about 5.5, these ions, assisted by statherin and proline-rich proteins that keep them in solution, redeposit into partially demineralised enamel.
- B. This reverses the chemistry. Lowering pH drives demineralisation. Saliva raises pH through its bicarbonate, phosphate and protein buffers, which is what permits remineralisation.
- C. Salivary glands do not synthesise fluoride. Salivary fluoride comes from systemic and topical exposure, and while it catalyses remineralisation it is not the source of the mineral.
- D. Salivary flow does clear debris, but mechanical washing is a clearance function. Remineralisation itself is a chemical process driven by ionic content.