Crowns may be needed for the following:
If a tooth has a very large amount of decay, then a crown
or an inlay/onlay
becomes a more dependable long-term solution compared to just having a tooth filling
There are limitations with any large filling packed into a tooth by the dentist. If the material is amalgam
it will expand slightly as it sets and if it is composite
it will shrink slightly.
The larger the filling the bigger this effect and the less likely the filling is to last long term. It is also more difficult to recreate the form and contacts of the tooth, when most of it has been destroyed.
A crown can help to protect the remaining weakened tooth structure underneath. A filling will need to be carried out anyway, if the tooth is to have a crown. It is this tooth/filling combination which will be filed down to form the core on which the crown sits.
An inlay/onlay is an alternative solution
, which like the crown is made in the lab and is bonded in passively, i.e. made to measure so it puts no force on the remaining tooth.
Sometimes you may have had a large filling that has failed, or another piece of that tooth that breaks away.
It may be possible to repair the tooth or to replace the filling but it is likely that at some point it will fail again and you will have to proceed to a crown.
Sometimes it is more sensible and more economical to proceed to a crown sooner.
Every time you fill a tooth, you remove a little more tooth structure- if the filling is small this is not a problem, but if the filling is large then maintaining as much sound strong tooth, to act as part of the core, is important for a successful crown.
Whilst you can generally always progress to a crown, there is a point at which it becomes the most sensible treatment option to keeping the tooth long term.
Sometimes the only way in which worn teeth can be built back up to a normal height with sufficient strength to last is by having crowns.
When crowns are being placed for severely worn teeth, a number of crowns are often needed and in some circumstances it may be necessary to change the bite.
Sufficient wear to require a crown would not come from tooth brushing abrasion
, but erosion
(having too much acid in your diet or gastric reflux) ,or attrition (grinding/ bruxism)
,or as is most often the case, a combination of the two.
Because wear often makes teeth shorter and crowns need a certain amount of tooth (at least 3mm in height) to be retentive (stay on well), the bite may need to be opened or crown lengthening done to make a placing crowns possible.
You may also need a crown for aesthetics reasons. Crowns (like veneers
) can change the colour and shape of teeth.
They can be placed on healthy teeth to improve their appearance, but as they are very destructive, wherever possible it is best to avoid crowns on virgin (untouched) teeth.
However, If you have fractured a large piece of a tooth, a crown can sometimes be a more appropriate choice, to give the tooth back its natural look and use, rather than having a filling or veneer.
The treatment decision depends on the a number of factors, including how much tooth has gone, how you bite your teeth together, the cost and your aesthetic requirements.
The dentist will discuss the advantages and disadvantages of all these treatment options with you, to allow you to make a decision.
- A previous crown has failed
When you have a crown, from that point on, you are always going to need a one. So if a crown fails, another crown will be needed to replace it.
It is important the dentist establishes the reason for failure and takes steps to try and prevent this from happening again.
- To hold together a cracked tooth
Sometimes a crown can be placed to protect a cracked tooth. If you look in a bright light, teeth have all sorts of cracks and fracture lines running through them - these are generally not a problem.
If a tooth however, has a functional crack often called cracked tooth syndrome
, it can sometimes need a crown to hold the tooth together, ensuring an even pressure on the tooth to prevent the crack from extending further.
A crown is not always necessary- treatment depends on the location, the depth of the crack and what else is going on with the tooth. Sometimes, the result is that a piece of tooth fractures off that can simply be replaced by a new filling. Other times, it can be a lot more complicated involving the nerve and needing a root canal or extraction
Teeth that have been root filled are much more brittle than living teeth which have a nerve and blood supply.
They can fracture easily with uneven pressure, so it is the recommendation of both the American Dental Association
and Australian Dental Associations
that posterior (back teeth), which are subject to great force during chewing, are placed with full coverage restorations if they have been root filled. This is possible with an amalgam filling or composite filling, but the most reliable method is with a crown, which acts like a helmet, bracing the weaker tooth underneath.
Whilst a tooth can still potentially fracture, a crown makes this much more unlikely, so the sooner this is done following the root canal the better. Before the procedure is carried out, the tooth should have settled down and should not be painful.
- As part of a dental bridge
A standard dental bridge involves a crown on teeth either side of the space, with a fake tooth attached in the middle. See- Bridges
, for more information.
An implant integrates with your jawbone and essentially replaces the root of the tooth. A crown is needed to make implants look like teeth again and fill spaces for aesthetics and chewing. If multiple spaces are present an implant may support a denture or a bridge instead.