Root caries: cementum demineralises at a higher pH than enamel

Root caries is the form growing most as the population ages, and the one on which protocols designed for enamel work least well.

The reason is chemical before it is behavioural. Enamel begins to demineralise around pH 5.5, while cementum and root dentine begin as high as around 6.2.

That difference looks small and is not: it means the root surface demineralises during acid episodes that enamel tolerates without consequence.

A patient with recession is therefore exposed to a risk their own enamel does not run, on the same diet and with the same hygiene as before.

The root also has a lower mineral content and a greater organic component, which makes progression faster once it begins.

The lesion appears as a dark area at the neck, often shallow but wide, encircling the tooth along the gingival margin rather than digging deep.

This makes it hard to restore, because the margin is subgingival, isolation is difficult, and adhesion to cementum is less predictable than to enamel.

It follows that prevention matters more here than elsewhere: a root lesion intercepted and remineralised avoids a restoration that will be imperfect anyway.

High-concentration fluoride is the principal tool. Toothpastes at 5000 ppm are indicated in at-risk patients and their effect on root caries is documented.

They are used in place of the usual toothpaste rather than in addition, and the method matters: apply, brush, spit without rinsing, to leave the fluoride in contact.

The patients to identify are recognisable: multiple recessions, medication-induced xerostomia, reduced dexterity, wearers of partial dentures whose clasps retain plaque at the necks.

Fluoride varnishes applied in the surgery complement home use in high-risk cases, and frequency is set on risk rather than on the calendar.

In summary: the root demineralises at pH 6.2 against enamel's 5.5, the lesion is wide and hard to restore, prevention is worth more than restoration, 5000 ppm replaces the usual toothpaste, and one does not rinse after brushing.