Tooth necks and root caries

A tooth consists of two very different parts. The crown is covered with enamel, the hardest material in the body. The root is not — it carries only a thin layer of cementum over the softer tooth tissue. As long as the gum covers it, that plays no part. Once it is exposed, the situation changes fundamentally.

Why the root is more sensitive

• It dissolves earlier. Enamel is attacked from a pH of about 5.5, the root surface already from about 6.2 — considerably earlier and therefore considerably more often in a day.
• It is softer. Caries spreads there faster and across a surface rather than into the depth.
• It is sensitive. Fine tubules run through the tooth tissue to the nerve. Cold, heat, sweet and sour are transmitted directly.
• It is poorly visible. Root caries is often only noticed late.

Why the gums recede

• Brushing too hard with a hard brush and horizontal scrubbing movements. The most common cause in people with otherwise healthy gums.
• A past periodontitis. After successful treatment the swelling recedes and the root is exposed — that is a sign of healing, even if it looks otherwise.
• Thin gums as a predisposition.
• Tooth grinding and incorrect loading.
• Piercings, which rest permanently against the gum.

Gums that have receded do not grow back by themselves. In selected cases they can be covered surgically; that is demanding and not sensible everywhere. More important is to stop the recession — and that almost always succeeds through brushing technique.

Against the sensitivity

• Toothpaste for sensitive teeth with potassium nitrate, stannous fluoride or arginine. It needs two to four weeks of regular use — anyone who gives up after three days throws away the effect. One trick: put a little paste on the sensitive spot with a finger and let it act, instead of rinsing it away at once.
• A low RDA value. Whitening pastes with high abrasiveness are the wrong choice here.
• Soft brush, little pressure, wiping rather than scrubbing movements.
• fluoride varnish at the practice — it closes the tubules and often works immediately.
• Limit acid. Fruit juices, soft drinks and vinegar open the tubules again.
• Do not brush after something acidic; wait half an hour.

If the pain persists despite everything, or becomes stronger, it should be examined. Persistent sensitivity can also come from a crack, a leaking filling or incipient caries.

Preventing root caries

Here fluoride in a higher concentration counts, because the surface is more vulnerable:

• A toothpaste with 1,400 to 1,500 ppm as the basis.
• A fluoride gel once a week, in the evening after brushing, with nothing to eat or drink afterwards.
• Where the risk is high, a toothpaste with 5,000 ppm on prescription. It is made for exactly this situation.
• Fluoride varnish at the practice, several times a year.
• Clean the tooth necks specifically — with interdental brushes of a suitable size, which also reach the concave surfaces of the root.
• Make sure there is saliva: drink, sugar-free chewing gum, raise the subject of a dry mouth.

If root caries has already arisen, it is filled. That is more demanding than a filling on the crown, because the site often lies at the gum margin and is hard to keep dry. The earlier it is found, the simpler — another reason for short check-up intervals.