Boundary Implant Centre

Dr S. Boji

The digital smile clinic

Why do I need a crown after root canal treatment?

You may have recently found yourself in need of having root canal treatment.

The dentist has now advised you to have a crown or an onlay, but why?


I have just had a root canal filling do I need a crown? (Or onlay)

After a root canal treatment, the body of the tooth is inherently weaker. Therefore, it’s necessary, especially for your back teeth, to have a crown/onlay placed on the tooth.

Root canal treatment is performed over one or two visits to remove the infected pulp from the tooth root. This is likely to have been performed to save the tooth as well as prevent decay and infection spreading to other teeth.

It’s important to remember that a root canal treatment is performed on a dead tooth, once the filling has been placed the tooth is more at risk of fracture. If this happens it normally means the tooth will need to be extracted.

When you eat normal foods on a daily basis your teeth meet at different points on the surface of the tooth, it is possible that a tooth can break at any time, but it is 6 times more likely with root filled teeth.

You are likely to bite down at some point on a part of the tooth with harder foods and it will crack. Whereas, when you place a crown or onlay, you cover the whole biting surface and thus the load is spread across the whole tooth and protected at all four corners.

This makes it much less likely to break (it is not a case of never) but much less likely.




What is a Dental Crown ?

This image below shows perfectly what a crown is and what it does .

dental crown | Los Algodones Dentists



And only is slightly different that it doesn’t cover all of the tooth, most dentists offer crowns. As seen below. ( onlay is the middle one)

Dental Inlays & Onlays San Antonio




What are dental crowns made of ?

Permanent crowns can be made from many different materials. These materials can include:

  • Metal: There are several metals that can be used in dental crowns, including gold, palladium, nickel and chromium. Metal crowns rarely chip or break, last the longest in terms of wear down and only require a small amount of your tooth to be removed. They can also withstand biting and chewing forces. The metallic colour is the main drawback of this type of crown. Metal crowns are a good choice for out-of-sight molars.
  • Porcelain-fused-to-metal: This type of dental crown can be matched to the colour of the teeth that’s next to the crown. They have a more natural tooth colour. However, sometimes the metal under the crown’s porcelain cap shows through as a dark line. Other cons include the chance of the crown’s porcelain portion chipping or breaking off and the crown wearing down the teeth opposite it within the mouth. This wear on the other teeth specifically affects the teeth that meet the crown on the top and bottom of your mouth when it’s closed. Porcelain-fused-to-metal dental crowns can be a good choice for front or back teeth.


  • All-ceramic or all-porcelain: These types of dental crowns provide the best natural colour match compared to any other crown type. They’re also a good choice if you have metal allergies. However, they aren’t as strong as porcelain-fused-to-metal crowns. They can also wear down the teeth opposite them in the mouth a little more than metal or resin crowns. All-ceramic crowns are a good choice for front teeth.



How is the tooth made ready for the crown/onlay?

This is carried out over two visits.

At the first appointment (normally about 40 minutes in length) the dentist will take a first mold of the tooth. This is done by putting a tray in your mouth the same shape as your teeth with a putty inside, you bite down on it and when it sets it is removed.

At Boundary Implant centre we can also do this with a digital wand to make it much quicker and more pleasant.

This mold is used to allow a dental technician to see how your teeth are set up to allow them to make a crown to fit your bite.

The dentist will then shape your tooth to allow for clearance to fit a crown over (as seen the  photo above)

Once this is carried out, they will then take a second mold of the tooth, which allows the technician to pour plaster of paris into it to, they will then  make a model to build the crown upon.

The Dentist will then place a temporary filling over the tooth (care is needed during this time)

You will be asked to return to the practice 1-2 weeks later to have the crown cemented into place.


How long does a crown last?

It is worth saying that any root treated tooth can have a guarded prognosis, simply because teeth are never meant to have fillings in them so once they are treated, they always carry a higher risk of problems.

Having said this, they can last for many years and never cause a problem.

Crowns too can last 20 years plus, with good oral hygiene, care with hard and sticky foods and regular check-ups to monitor the tooth.


We hope this helps answer any questions you may have about root filling and crowns.

Call is today if you need to book in 01273 418404