Filling, onlay, or crown: what fits a damaged tooth
When a tooth is decayed or cracked, the right fix depends on how much of it is damaged. A filling handles small damage and keeps the most natural tooth, an onlay covers moderate damage, and a crown wraps the whole tooth but removes the most healthy structure. Slide to about how damaged the tooth is to compare the cost and the tradeoffs.
Choosing the right fix
Matching the fix to the damage
It comes down to how much of the tooth is gone. Small to moderate decay, up to roughly a third of the tooth, usually takes a filling at about $226. Moderate damage, roughly 30 to 60 percent, is onlay territory at about $900, which is a lab-made piece that covers the damaged part while sparing the rest. Past that, or for a cracked or root-canal-treated tooth, a crown at about $1,300 caps the whole thing. Slide the damage level in the tool to see which options fit and what each one costs.
Why not just crown it
Because a crown removes the most healthy tooth of any option. To seat a full cap, the tooth gets filed down on every side, and that enamel never grows back. Dentistry's working rule is the least invasive fix that will hold, because it's cheaper now and it keeps your options open later, since a filled tooth can still be crowned someday but a crowned tooth can't go back. A crown is the right call when you actually need it, not the default.
The onlay: the middle option nobody mentions
An onlay is the middle option most people have never heard of: a custom lab-made piece, usually ceramic, bonded over the damaged area like a partial crown. It preserves way more tooth than a crown and outlasts a big filling. Not every practice offers them, since they take lab work and a second visit, which is part of why quotes jump straight from filling to crown. If your damage is in that middle zone, it's a fair thing to ask about.
Costs and lifespans side by side
A filling is the cheapest and lasts about 5 to 15 years, but in a big cavity it can flex and fail early. An onlay costs several times a filling and usually lasts 10 to 15 years while keeping the tooth strong. A crown costs the most, lasts a similar 10 to 15 years or more, and is the only option for a tooth that's lost its structure. The tool prices all three against your damage level and flags whatever doesn't fit.
Common questions
Can a filled tooth get a crown later?
Yes, and that's the whole point of starting small: a filling keeps every future option open, while a crowned tooth can never go back to a smaller restoration.
What is the price gap between an onlay and a crown?
About $900 versus about $1,300. But the onlay's real value is the healthy tooth structure it saves, not just the $400 you keep.
How much tooth damage forces a crown?
Once you're past roughly 50 to 60 percent damage, or dealing with a cracked or root-canal-treated tooth, a crown is usually the only fix that holds. Below that, the smaller options deserve the first look.