A dental crown is a tooth-shaped “cap” that is placed over a tooth to restore its shape, size, strength, and improve its appearance. A crown is placed over two appointments, one to prepare the tooth for the crown and a second to fit the lab-made crown. When cemented into place, crowns fully encase the entire visible portion of a tooth that lies at and above the gum line.
Why is a crown needed?
To protect a weak tooth (for instance, from decay) from breaking, or to hold together parts of a cracked tooth
To restore an already broken tooth, a tooth that has been severely worn down, or to support a tooth with a large filling when there isn’t a lot of tooth left
To cover a dental implant
To make a cosmetic modification
To cover misshapen or severely discoloured teeth
To strengthen a root filled tooth - all root filled teeth should have a crown or at least onlay covering them
With scanning and 3D printing technology crowns are now made of scientifically advanced materials. The two main materials we use at Gwynne Dental are Zirconia and Emax.
Emax Crowns
These are special type of crowns made from lithium disilicate material. They are made from a single block of this material which makes it a high strength crown free from imperfections. Lithium disilicate is known for its superior strength and appealing aesthetics as a restorative crown material. E-max crowns are slightly translucent and come closest to matching your natural teeth colour. This property has made it a great choice for restoration of front teeth.
Zirconia
Zirconia is the ceramic form of zirconium and is closely related to titanium. It is a tooth coloured, strong, yet a lightweight ceramic with fantastic bio-compatibility. It is stronger than Emax, but not quite as aesthetic. Zirconia can be used for all teeth, but especially for back teeth (e.g. molars), where higher strength is required.
Risks
The main risk of having a crown placed on a ‘live’ tooth is that the tooth becomes non-vital. This can cause discomfort and require the tooth to be root filled. It is best not to root fill a tooth first, unless it is necessary, as a ‘live’ tooth is much stronger.
Bridges
Bridges are made from the same materials and act to close a missing tooth gap. This is done by crowning adjacent teeth and attaching the ‘false’ tooth to the crowns either side which ultimately support it. This takes 2 appointments as per crowning a tooth and has a very similar process.
The Process
It usually takes two appointments for a crown or bridge to be made following the initial consultation. An x-ray will usually be taken prior to the treatment starting to ensure health of the supporting tooth and tissues.
The tooth is numbed using local anaesthetic and then prepared by reducing the tooth by around 2mm, following the original contours of the tooth. Historically, preparations for crowns were very aggressive, leaving a small peg shape tooth, this is no longer necessary due to advances in dental materials and techniques.
A 3D scan of the upper and lower teeth is taken to make sure both the fit, and bite of the crown is perfect. A colour-match or “shade” will be taken to ensure a seamless appearance with the rest of the teeth.
A temporary crown is made at this appointment which will be in place for around 2 weeks. This is designed to be removed easily so it is important to avoid hard, sticky foods or flossing around the temporary crown for this interim period.
The second appointment will be much shorter and may sometimes involve numbing. The temporary will be lifted off and the new permanent crown/bridge tried in to make sure it fits and looks perfect. When both the dentist and patient are happy, the permanent crown/bridge is cemented in place with an incredibly strong cement.