Your teeth are shorter than they used to be

Pull up a photo of yourself from fifteen years ago and look at your smile, not your hairline. There is a reasonable chance more tooth was showing then.

Under normal chewing, enamel wears slowly, a few hundredths of a millimeter a year. If you grind or clench, and a great many people do without knowing it, that rate multiplies, and a heavy grinder genuinely can lose a millimeter in a decade. It happens slowly enough that you never notice it happening, and it changes your face in ways that get attributed to general aging.

What actually wears down

Three things are usually happening at once, and they compound:

• Attrition. Tooth against tooth. Grinding and clenching, often during sleep, often driven by stress. This is the big one and it flattens the biting edges of the front teeth first.
• Erosion. Acid softening the enamel so it wears faster. Citrus, soda, sports drinks, wine, and reflux, which many people have without heartburn.
• Abrasion. Mechanical wear from aggressive brushing with a hard brush, which notches teeth at the gumline.

Why it reads as age

Two separate effects, and both are visible before anyone can name them.

The first is what shows when you talk. Young front teeth sit slightly below the upper lip at rest and show a few millimeters when the mouth is relaxed. As the edges wear flat, that display goes to zero. It is one of the more reliable visual cues of age, and almost nobody consciously registers it. They just read the face as older.

The second is structural. Your back teeth set the vertical height between your upper and lower jaw. When they wear down, some mouths compensate and keep their height, and some do not. Where height is lost, the jaw closes further, the chin rotates up and forward, and the distance from nose to chin shortens. Soft tissue that used to be supported now has less to sit over. Corners of the mouth turn down. Lines around them deepen. People spend money on the skin. The problem is underneath it.

The part that gets missed

Enamel runs up to about 2.5mm at its thickest on a biting surface. Once it is through, the dentin underneath wears at roughly twice the rate, so the whole thing accelerates. It is why a mouth can look fine at forty and be a real problem at forty-eight.

Beyond a certain point, teeth become sensitive, prone to fracture, and much more complicated to restore, because there is no longer enough tooth to attach anything to without first rebuilding the bite height. Catching it earlier is dramatically less involved than catching it later.

What can be done about it

In rough order of how much intervention is involved:

• A night guard. If wear is caught early, protecting the teeth may be the entire treatment. It protects against night grinding, which for most grinders is the main driver, without changing anything about your teeth.
• Bonding. Worn edges can often be rebuilt with composite added directly, with little or no drilling. Conservative and reversible.
• Porcelain. When multiple teeth have lost significant length, restoring both the look and the function usually means ceramic.
• Full rehabilitation. When the bite height itself has collapsed, rebuilding it is staged, deliberate work. It is also the case where the change to the face is most dramatic.

How to check yourself

Look in a mirror and let your face go completely relaxed, lips slightly parted, not smiling. If no upper tooth is visible at all, there is a good chance you have lost length. Then look at the biting edges: young front teeth have subtle rounded bumps along the edge, and if yours are a flat straight line, that is wear.

Neither of those is a diagnosis. But both are worth mentioning at your next appointment, because the answer at that point may be a night guard rather than anything permanent.