An engineering judgment about what's left.

Remaining tooth structure, and nothing else. A filling repairs a hole in a tooth whose walls can still carry the chewing load; a crown takes over when those walls cannot, covering the whole tooth and bearing the force itself. Every honest crown-versus-filling call is an engineering judgment about how much sound tooth is left after the decay or crack comes out, which is why the answer changes mid-appointment sometimes: what looked like a filling on the X-ray reveals thinner walls once the damaged material is removed, and a dentist who warns you of that possibility beforehand is doing it right.

The trap on each side is worth naming. Overfilling, stuffing an ever-larger filling into an ever-weaker tooth, feels thrifty and is not: a big filling in thin walls acts as a wedge, and the crack it eventually causes can travel below the gumline where nothing saves the tooth. Overcrowning, reaching for full coverage when a filling would genuinely hold, spends your money and your enamel on insurance you did not need. The practice rule here is the repair ladder: the smallest fix that will truly hold, chosen with the evidence on screen.

A filling costs less, takes one shorter visit, and spends less tooth, which is why it wins whenever it genuinely can. A crown costs several times more and, in most offices, takes two visits and a temporary; in this office same-day crowns often compress that to a single day, which removes the convenience penalty from the crown side of the ledger without changing the engineering question. The long-run arithmetic matters more than the sticker: the wrong filling that becomes a crack can become a root canal plus crown, or an extraction plus implant, each step multiplying the original price, so the cheapest treatment is the right-sized one, not the smallest one.

Cracks deserve their own caution flag in this decision because they masquerade: a tooth that twinges on releasing a bite, or protests specific hard foods unpredictably, is describing a crack even when X-rays show nothing, since cracks run in planes film misses. That pattern shifts the calculus toward coverage sooner rather than later, and it is worth reporting exactly, twinge on release, not constant ache, at your exam.

One more honest wrinkle: the answer can legitimately change mid-appointment, and being told so in advance is a mark of the right office. Decay's true extent hides under enamel and old fillings, so what imaging read as a large filling occasionally reveals, once cleaned out, walls too thin to trust, and the plan upgrades on the spot with your say-so. The reverse happens too: suspected crown territory turns out shallower than feared, and the smaller repair wins after all. The commitment that holds either way is that you see what was found and decide with the evidence in front of you.

Insurance treats both as core restorative care: most plans, including Delta Dental, Blue Cross Blue Shield, Cigna Dental, Altus, Dominion National and MetLife, contribute toward clinically necessary fillings and crowns at their set percentages, verified here before anything is scheduled, with your written share first. And when your case is genuinely borderline, expect to hear both numbers and both arguments, because the borderline is where your priorities, not just your anatomy, deserve a vote.