Mish Sachdev

What’s the difference between crowns and onlay?

If you damage a tooth, your dentist may suggest using a crown to repair it. There may also be other options, such as an onlay. Learn more about the options available to you, the differences between them, and which might be the best option for your teeth, to restore your smile and give you back your confidence.

What is a dental crown and why might you need one?

A dental crown is a structure that covers your whole tooth. Each crown is bespoke, made to fit with your teeth and your mouth.

The primary reason why you might have a dental crown is to prevent your tooth from cracking. If you have decay, your dentist will probably remove it and then restore your tooth with a filling. Depending on how big the area of decay is, it can leave thinner areas on the remaining tooth.

Biting down onto tooth surfaces like these will send a large vertical force straight down into the bottom of the tooth. After a while, microcracks will start forming until suddenly, a larger area can crack and you might lose part of the tooth. If the damage isn’t too great, then we can normally save the tooth by repairing it with a crown (or perhaps a filling, depending on the circumstances.) However, if it’s a large piece, do bear in mind that the tooth might need to be removed. Your dentist will be able to advise you in full if you find yourself in this situation. Of course, we would try our best to prevent this from happening and would try to use a crown as a helmet for the tooth where possible. This will protect it from further cracks and make it more stable.

  • To improve the appearance of the tooth. Crowns can be placed to improve the appearance of teeth. This could range from one single tooth, to a whole arch.
  • To provide a seal after root canal treatment. When teeth have been root filled, you need a good seal to prevent the bacteria in the mouth infecting the tooth again. A crown is one of the best ways to offer this kind of protection following your treatment.

What is the difference between a crown and an onlay?

In essence, both a crown and an onlay will do the same thing. The main difference is that an onlay will save a lot of your tooth structure. Over the years, standards have improved and the techniques we use have changed, allowing dentists to offer a variety of options to patients.

In the past, we had to use crowns to cover the whole tooth, as dental cement was not very strong and this was the best way to retain the tooth. The more it wrapped around the tooth, the longer is was going to last.

Nowadays, the cement that dentists use is very good quality – it can be used just to cover the important parts of the tooth that really need protecting. The less tooth we cover, the more tooth structure we can save.

However, to prepare your teeth for a crown, we must first begin by grinding down the tooth itself. An onlay will save a great deal of the tooth structure, as preparation for the average crown will remove around double the amount of tooth as preparation for the average onlay would.

Some dentists still use old techniques. Make sure you book a consultation first to understand what will happen to your teeth during the procedure.

Is an onlay always better than a crown?

At Gentle Dental Care we will always do the best thing for your mouth. If a crown needs replacing, then it’s a no brainer – you replace it with another crown. If your bite is not perfect and you have many missing teeth then the restoration is going to have more of an impact so then a crown may be better. However, if you need less tooth coverage, an onlay may be the better option. There are lots of factors that influence our decision so there is no best option in general terms – we do whatever is best for that particular situation.

If you would like to discuss crowns and onlays, call our friendly reception team on 020 8655 1118 and we will be happy to help.