Crown or filling: how your dentist decides

You have a cavity, a cracked tooth or an old filling that is breaking down, and your dentist has said the word “crown”. A crown usually costs more and takes longer than a filling, so it is fair to ask why a filling will not do.

The short answer is that the choice depends on how much healthy tooth is left and how much force that tooth has to handle. This article explains what your dentist is looking at, the options that sit between a filling and a crown, and the questions worth asking before you agree to either.

What is the difference between a filling and a crown?

A filling repairs a hole in a tooth. The decayed or damaged part is removed and the space is filled. At BWG Dental Centre, most fillings are white fillings, also called bonded or composite fillings: a tooth-coloured resin is shaped inside the tooth and hardened with a light. The rest of the tooth stays as it is and carries the load of chewing.

A crown covers the whole visible part of the tooth, like a cap. The tooth is shaped to make room for it, and the crown is made to fit and then cemented in place. Crowns can be made from porcelain, ceramics, metals or porcelain fused to metal. Because a crown wraps around the tooth, it holds the remaining tooth together rather than relying on it. Our dental crowns page explains the treatment in more detail.

Why would a tooth need a crown rather than a filling?

A filling depends on the surrounding tooth to stay strong. When too much of the tooth has been lost, the walls left around a filling can become thin, and thin walls can crack under the pressure of chewing. Your dentist is weighing several things at once:

• How big the damage is. A small or medium cavity usually has plenty of strong tooth around it, and a filling suits it well. When decay or an old filling takes up a large share of the tooth, a crown may protect what is left.
• Whether a cusp is broken or weak. The cusps are the raised points on the chewing surface of back teeth. When one breaks off or is undermined, a filling alone may not restore the tooth’s strength.
• Cracks. A tooth with a crack can sometimes be held together by a crown, which may stop the crack from spreading. Not every crack can be saved, so your dentist will explain the outlook.
• Root canal treatment. Back teeth that have had root canal therapy are often recommended a crown afterwards, because the tooth can become more brittle and is at higher risk of breaking.
• Where the tooth is. Molars take much more chewing force than front teeth, so the same size of damage may be treated differently depending on the tooth.
• Grinding or clenching. Heavy forces at night can break large fillings and weakened teeth, which can tip the decision toward more protection.

Is there anything between a filling and a crown?

Sometimes. An inlay or onlay is a custom-made restoration that fits into or over part of the tooth, rather than the whole of it. An onlay can replace one or more cusps while keeping more natural tooth than a crown would. Inlays and onlays are made outside the mouth from an impression or a digital scan, then bonded in place.

They are not right for every tooth, but they are worth asking about when the damage is too large for a comfortable filling and you would like to keep as much natural tooth as possible. We list inlays and onlays among our restorative services, and your dentist can tell you whether one suits your tooth.

Is a large filling ever the right choice?

Yes. A large filling can be a reasonable choice when the remaining walls are still thick enough, when the tooth does not take heavy chewing force, or when a crown is not the right step yet. Some people choose a filling for now and plan a crown later. That is a valid decision as long as you understand the trade-off: if a large filling or the tooth around it breaks, the repair may then need to be more involved.

Your dentist should explain what could happen with each option, so you can choose with the full picture rather than on cost alone.

What does each treatment involve?

A white filling is usually done in one visit. The area is frozen, the decay is removed, the tooth surface is prepared so the material bonds, and the resin is placed in layers and hardened with a light. It is then shaped and polished to blend in with your tooth. The white fillings page walks through those steps.

A crown is a longer process. The tooth is frozen and shaped, an impression or scan is taken, and the crown is made to fit your tooth and bite. When the crown is ready, your dentist checks the fit, colour and bite before cementing it.

How long does each one last?

Neither a filling nor a crown lasts forever, and how long either lasts varies a great deal from person to person. It depends on the size of the restoration, the material, the forces on that tooth, grinding, diet, and above all on home care and regular checkups. Decay can still form at the edges of a filling or a crown, so brushing, flossing and routine visits matter just as much after treatment.

Questions to ask your dentist

If you are deciding between a crown and a filling, these questions can help:

1. How much healthy tooth is left, and how thick are the remaining walls?
2. What is the risk if I choose a filling now?
3. Would an onlay be an option for this tooth?
4. Is there a crack, and if so, what is the outlook?
5. Which crown material do you suggest for this tooth, and why?
6. How many visits will this take, and what happens in between?
7. What is the cost of each option, and what does my plan cover?

Talk to us about your tooth

You can learn more on our dental crowns page, or call BWG Dental Centre in Bradford at (905) 775-7005 or use our appointment request form. Dr. Riojas-Ozturk will look at the tooth with you and explain the options.