If a tooth has lost most of its natural crown structure due to extensive repair after removal of decay, and particularly if it has also had root canal treatment, it is going to be very weak and brittle.
It is then at significant risk of fracture or even splitting during normal chewing function. Once that happens , that tooth will become very painful and may be un-saveable.
The solution is to strengthen and protect it with a ‘kind of helmet’ called a dental crown. The outside of such a weak tooth needs to be cut back about 1.5mm all round and then a new synthetic hard shell is made to cover it .
That shell is made of metal, sometimes with varying amounts of gold and /or hard porcelain . The latter is used to make the tooth look exactly like the real thing . The final result should look like a tooth , have the same dimensions as the original tooth and will protect the underlying natural tooth and its roots during function. The strongest and most aesthetic crowns are those that have a metal shell to which tooth colour matched porcelain is bonded ( in a laboratory).
Crowns are usually made by a dental technician in a laboratory on a model that is an identical replica of the tooth the dentist has prepared in the surgery. So if it fits the model, it will fit exactly the same way in the mouth. During the few days it takes the technician to make the crown, the patient has a plastic temporary crown fitted to the tooth. This is replaced at the second appointment with the final ‘permanent’ crown that is cemented on .
Crowns are not ‘expensive’ fillings ; they are advised and used in situations where a filling would not be strong enough because too much natural tooth is missing , and the tooth needs to be supported and strengthened.
The fee charged not only reflects the time it takes the dentist, his or her expertise, the materials used but also the fee payable to the technician .
A beautiful, strong , well made, perfectly fitting crown, is a significant investment that should be very worthwhile , providing many years, even decades of protection to a tooth that should last a lifetime.