This isn’t as clear-cut, as for say a filling, because it is more subjective on the dentist’s part.
If the tooth has had a crown before, which has failed, it will definitely need a crown.
The same goes for the tooth, if it has had a post and core
If the dentist has done a root canal on a molar tooth they will, for reasons discussed in the root canal series, suggest a crown to protect it.
If they notice a root filling done by another dentist or endodontist - for example on a screening X-ray
- they will ask questions to determine if the root canal has been successful and if so, again probably suggest the tooth be crowned to protect what’s underneath for the long term.
When it comes to a heavily filled tooth or a broken tooth- there is much more variation and there are no strict rules as to what needs a crown; what would be best with an inlay or onlay
and what could be just filled.
Add into this equation the experience and ability of the dentist; some dentists will be able to place very large fillings to a very high standard that have a good prognosis and other dentists will find providing a crown a much more consistent choice for them.
The circumstance we want to avoid is having a weak core of mostly filling and very little strong tooth to support the crown. The chances of the crown breaking off with the core inside, is much higher when this is the case and we don’t want to see this happen!
When I know a patient is coming in with a crown that has come off
, I always keep my fingers (and toes) crossed, that the core is still in place on the tooth and not inside the crown. When this happens, the prognosis despite all best efforts is not as good, since the remaining tooth often lies flat against the gum and achieving a good foundation (dentist's may refer to this as a ferrule) to resist sideways chewing forces becomes difficult.
Often an elective root canal will need to be done in order to place a post to retain a core for a new crown and as we know a post crown is pretty much our last attempt at saving the tooth. So we want to place the crown before it gets to this point and give the crown a solid core to ensure it lasts you for a good many years.
I personally recommend crowns to my patients in the following circumstances:
- When the filling will be inadequate, if for example, I cannot get it to create good contact points with the teeth either side so food packing may become a problem.
- Where I cannot restore the tooth aesthetically to the patient’s expectations by other more conservative options.
- If I cannot restore the tooth to the bite to allow proper chewing.
- If the filling is very large, replacing the majority of the tooth. That said, I often see large amalgam fillings (less so composite but this will change) that have been in place for many years satisfactorily. I do not see the need personally to go crowning all these teeth that are functioning adequately- unless they fail in some way or you decide you want to make them tooth coloured in which case a crown is often needed.
- When the filling is likely not to last, I would recommend an indirect restoration (one made in the lab), a crown, or an inaly/onlay.
- When just refilling the tooth will compromise the structure of the core needed for a good crown.
- If you have had a root canal on a back tooth
- If you have had a post and core on any tooth
- Where you have a cracked tooth that requires protection
- As part of a full mouth rehabilitation
We discuss these in more detail on the next page. It is also important we also consider the rest of your mouth. For example if you are a heavy grinder , a crown might be considered due to the pressures that the tooth is likely to receive.