Dental Crown vs Filling: When Do You Need a Crown?

A filling replaces the part of a tooth that decay removed. A crown covers the whole tooth. The choice between them comes down to how much sound tooth structure is left, which is why the same symptom can lead to either answer depending on what the dentist finds.

The Difference in One Paragraph

A dental filling restores a cavity by replacing the decayed portion with a material bonded into place, leaving the surrounding tooth untouched. A dental crown covers the entire visible tooth, which means reducing the tooth first so the cap fits over it.

The consequence of that difference is structural. A filling relies on the remaining tooth to hold everything together. A crown takes over that job itself, which is why it is used when the tooth can no longer do it.

What Actually Decides Which You Need

The deciding factor is how much sound tooth is left after the decay is removed, and that is only knowable once the dentist is working. This is why a plan sometimes changes mid-appointment.

A small or moderate cavity in a tooth with solid walls around it is filling territory. Once the decay reaches a point where the remaining walls are thin, a filling would be sitting in a tooth that is likely to fracture around it.

Other factors weigh in besides the size of the cavity.

• Cracks running through the tooth, which a crown can hold together and a filling cannot
• A tooth that has had root canal treatment, since it becomes more brittle afterwards
• Repeated failure of previous fillings in the same tooth
• Heavy grinding, which loads back teeth far beyond normal chewing
• How much of the biting surface is involved rather than just the depth
• Whether the decay extends below the gumline

Whether any of these applies to your tooth is a clinical judgment made after examination and imaging.

What Getting a Filling Involves

A filling is usually a single appointment. The area is numbed, the decay is removed, and the space is cleaned and filled with a material shaped to match the tooth.

Composite is tooth-colored and bonded into place. Your dentist checks the bite afterwards, because a filling that sits high is uncomfortable and puts uneven force on the tooth.

Some sensitivity to cold in the days afterwards is common and usually settles. Sensitivity that worsens, or pain on biting that persists, is worth a call rather than waiting it out.

Our guide to what to expect from a filling covers the appointment in more detail.

What Getting a Crown Involves

A crown is usually two appointments. At the first, the tooth is prepared by reducing it, an impression or scan is taken, and a temporary crown is fitted while the permanent one is made.

At the second visit the temporary comes off, the permanent crown is checked for fit and bite, and it is cemented into place. Some practices offer same-day crowns milled on site, which changes the sequence.

Temporary crowns are deliberately less firmly attached than the final one. Sticky foods can pull them off, and if that happens you should call rather than leave the prepared tooth exposed.

Materials differ, and the choice affects appearance and durability. Our guide to what to expect from a crown covers the options.

Choosing the Cheaper Option Is Not Always Cheaper

A filling placed in a tooth that needed a crown tends to fail, and the failure is rarely convenient. A cracked cusp or a fractured wall can turn a restorable tooth into one that needs more extensive treatment.

That does not mean crowns are the safer default. Preparing a tooth for a crown removes sound structure permanently, and doing that to a tooth that a filling would have served is its own loss.

The right question at the consultation is what specifically about this tooth points to one over the other. A dentist should be able to show you on the image.

How Long Each Tends to Last

Longevity for both fillings and crowns is driven more by the tooth and the person than by the material. Where the restoration sits, how heavily it is loaded, and how well the mouth is cleaned all matter more than the brand of composite or ceramic.

Fillings in small, well-supported cavities can serve for many years. The same material in a large restoration on a heavily loaded molar works harder and is more likely to need replacing.

Crowns fail at the margin more often than through the crown itself. Decay can start where the crown meets the tooth, which is why a crowned tooth is still examined and still needs flossing at that junction.

Neither is permanent, and both are checked at routine visits. Catching a failing margin early usually means a simpler repair than waiting for symptoms.

Inlays and Onlays Sit in Between

An inlay or onlay is a restoration made outside the mouth and bonded in, covering more of the tooth than a filling but less than a crown. They exist precisely for cases that fall between the two.

An onlay can cover one or more cusps while leaving the rest of the tooth unprepared, which preserves structure a crown would have removed.

Whether one suits your tooth depends on which surfaces are involved and how much support remains. Our inlays and onlays page covers where they apply, and our restorative dentistry page covers the broader range.

Get the Tooth Assessed

Mountainside Dental is a family-owned dental group with five offices across Southern California, open since 2004. An exam and imaging are what settle the question for a specific tooth.

Frequently Asked Questions