A filling replaces missing tooth material. A crown wraps what is left. The choice is mostly structural: how much sound tooth remains, and whether it can survive being loaded without being held together.
Removes less tooth, usually one visit, lower cost. Best when the cavity is small to moderate and the walls of the tooth are strong.
Crown — protective
Covers and binds the remaining tooth. More predictable when a large amount of structure is gone or a crack is present.
Onlay — in between
Covers part of the biting surface without full coverage. Sometimes an option when a filling is too little and a crown is more than needed.
The trade-off nobody enjoys
A very large filling in a weakened tooth can work — until the tooth flexes and a wall breaks, sometimes below the gum, which can turn a restorable tooth into an extraction. Choosing a crown earlier removes more tooth up front to reduce that risk.
That is the actual trade-off: conserving tooth material now versus reducing the chance of a bigger failure later. Reasonable people weigh it differently, and the right answer depends on your tooth, your bite, and your priorities.
What we can explain here — and what needs an exam
A page can inform you. It cannot examine you. Here is the honest line.
We can explain online
The structural logic behind each option
Why cracks change the recommendation
That an onlay is sometimes a middle path
What tends to drive cost differences
Determined after an exam
How much sound structure your tooth has
Whether a crack is present and how far it runs
Whether the nerve is involved
Which option is appropriate for you and what it costs
Ask why, not just what
If you have been told you need a crown, it is fair to ask what makes a filling insufficient in your case. Any dentist should be able to answer that clearly.
General information reviewed by Mankirat Gill, DDS · August 2026. This page does not replace an in-person examination. If you have severe pain, spreading facial swelling, or trouble breathing or swallowing, call us or seek emergency care now.