Crowns

When and why does a dentist recommend a crown for a tooth?

It is important to fully understand the rationale for recommending a tooth be crowned. Like fillings, crowns ‘restore’ the integrity of a tooth after it has been damaged either by trauma or disease (e.g. decay).

There will be times when the dentist recommends a filling, others when a crown is indicated, and obviously, times when one or another can fulfill the requirements.

What are the differences?

Function

A filling ‘fills a hole’. Usually, the hole is created by decay (infected caries) penetrating through the tooth enamel layer into the underlying dentine.

This decayed tooth material must be removed (‘drilled’ out) and replaced with a sealed synthetic (preferably tooth-coloured) material. Generally, this is a quartz composite. If the ‘hole’ is not too large and surrounded by at least two thick and strong enough enamel walls of the tooth’s natural crown… then the filling is the ‘appropriate’ restorative material.  Such a filling is ‘supported’ by the tooth.

The function of the crown is quite different to that of the filling.”

On the other hand, if the tooth is very damaged and a large proportion of the natural crown of the tooth is either already missing or needs to be removed because it is so badly decayed (infected), then one needs a restoration that actually strengthens and supports such a tooth. The function of the crown, therefore is quite different to that of the filling.

Most teeth that have undergone root canal treatment are already very damaged, and gaining access to the root canals for such a procedure (that ‘saves’ the tooth) inevitably requires removing even more of the ‘inside’ (or central part) of the tooth, further weakening it. Finally, root canal treatment dehydrates a tooth to a degree, rendering it more ‘brittle’ and even more prone to fracture or splitting due to normal functional forces.

That is the reason that, very often, the dentist strongly recommends that the patient does not delay too long before protecting a tooth with a crown after the root canal procedure has been completed.

Crowns before and after Cap City
Process

Usually, a filling needs to be placed in a tooth prior to the tooth then being restored with a crown subsequently. This would then be termed a ‘core’ filling as it acts as a supporting and retaining core for the crown. This is because the crown replaces the outside surfaces (about 1.5mm) of the tooth crown; the core filling fills the missing ‘inside’ of the tooth.

If a tooth is root canal-treated, one or two metal or fibre posts may be required to be placed within the (root-filled) canal/s of the tooth to help retain the core filling.

If the tooth is ‘alive’ (has not had root canal treatment) and the core filling needs additional retention … one or more tiny titanium pins would need to be ‘drilled and placed’ into the tooth before the core filling is placed around them.

Crown Materials

Several permutations are available… ‘overlays’ that are bigger than fillings but more ‘conservative’ than full crowns, and these restorations can be made of different materials. Generally, nowadays, dental restorative materials are almost always visually ‘tooth coloured’. Quartz composite material is the most commonly used for fillings and has well and truly taken over from the very old-fashioned silver-mercury amalgam.

Porcelain or its stronger ‘version’ and zirconium can also occasionally be used for fillings. These latter materials are laboratory-produced and certainly far harder and stronger than composite. So, they are certainly used for overlays and crowns. Not infrequently, particularly for very heavily damaged and root canal-treated teeth, a full porcelain over metal-based crown will be used.

The good old-fashioned gold overlay or full gold crown is still the best restorative material, but it is usually only used in areas that are never ‘seen’, such as the upper back part of the mouth.

Cost of a crown

Any restorations that involve gold, other metals, porcelain or zirconium (certainly such as crowns) generally must be made by a dental technician in a separate laboratory. Consequently, unlike composite fillings, which are placed and hardened by the dentist in one appointment, these need two appointments (one to ‘prepare’ and one to ‘fit’), and the fees tend to be far higher. A large composite filling can be £180- £325 and a full crown in the region of £850-£1,500.

Register as a new patient today.

clear aligners photo

WANT STRAIGHTER TEETH?

FREE CONSULTATION & SCAN