A crown is a type of dental restoration which completely caps or encircles a tooth or dental implant above the gum line and is typically bonded to the tooth using a dental cement. They are used to cover a tooth and restore it’s natural shape and size whilst providing added strength.
Crowns can provide many different functions. They can act as a protector to an underlying, weak tooth which may have been damaged by decay or trauma, and can protect and hold together a cracked tooth to prevent any further damage. When a tooth has been fitted with a large filling which leaves very little of the actual tooth remaining a crown may be fitted to provide extra support and also to give the appearance of a real tooth, they can also cover dental implants and misshapen or discolored teeth in order to provide a more pleasing aesthetic. They are used also in the formation of dental bridges, they can fix on to existing teeth so the bridge can fill the gap left after tooth loss.
Crowns can be made out of metal, porcelain fused to metal, all porcelain, resin or ceramic.
Metal crowns are probably the most durable out of all crowns but are less desired due to their metallic colour, they are usually a better choice for hidden molars as they can withstand chewing but do not spoil the overall aesthetic of the mouth too much. there is also very little wear and tear inflicted on to your other teeth with a metal crown. The metal used could be gold alloy or other alloys such as palladium or other base-metal alloys such as nickel.
Porcelain fused to metal (shown here) can be matched to your natural teeth and look most like natural teeth (next to ceramic) and so provide a more pleasing aesthetic. For this reason they are mostly recommended for the front teeth. However the surrounding teeth may be subjected to some wearing with these crowns and the porcelain portion could be prone to breakage. Although a more natural look can be achieved sometimes the metal underlying the porcelain can be exposed, especially at the gumline.
All porcelain and ceramic crowns are the most desired due to the fact they provide a more natural tooth color and they are an alternative to someone with metal allergies. However, porcelain and ceramic are less durable than metal and resin crowns and can cause damage to surrounding teeth. They are probably best used for the front teeth due to their aesthetics attributes.
Resin crowns are the cheapest option but are much less durable than porcelain fused to metal crowns and are more prone to fractures.
You may be fitted with a temporary crown which can be made in your dentist’s office as opposed to being sent to a laboratory. They can be used to cover an unfinished procedure and as a temporary measure whilst your permanent crowns are being made.
To begin your tooth needs to be prepared for a crown. In your first appointment your dentist may want to take an x ray to check the roots of the tooth. If there is extensive decay or a risk of pulp infection there may be cause for root canal therapy.
Prior to the fitting of your crown the surrounding area around your tooth will be put under local anesthetic and the affected tooth is filed down so as to make room for the crown (as shown in the video).
Prior to the fitting of your crown the surrounding area around your tooth will be put under local anesthetic and the affected tooth is filed down so as to make room for the crown (as shown in the video). The amount your tooth is filed down depends on the choice of crown, for example metal crowns are thinner and so require less of the tooth to be filed down. If, on the other hand, your tooth has suffered substantial loss it will be built up using filling material so it can support the crown.
After your tooth has been prepared your dentist will make an impression of your teeth to be sent to the laboratory to manufacture the crown. A cast of the surrounding teeth and the teeth above or below are taken to ensure the best fit possible which will not affect your bite (as shown in the video). If you have chosen a porcelain crown your dentist will select a shade which best matches your existing teeth.
Manufacturing time usually takes 2 or 3 weeks and in the meantime a temporary crown will be fitted which can be made of acrylic and fitted using temporary cement. Temporary crowns require some extra care as they are not made to last and so cannot take the same wear and tear of your natural teeth or permanent crown. You will probably be asked to avoid chewy or sticky foods, keep the majority of your chewing to the other side of your mouth without the crown and to slide rather than lift out dental floss when flossing. Lifting out the dental floss may remove the temporary crown.
On your next visit your dentist will remove your temporary crown and check the fit of your permanent crown. If everything is satisfactory you will again be put under local anesthetic whilst your permanent crown is fitted and cemented in to place.
Immediately following your procedure you may find your crown prone to hypersensitivity as the anesthetic wears off. If your existing tooth still has some nerve endings in it you may become sensitive to hot and cold, if this is the case it would be recommended to use toothpaste designed for sensitive teeth. If you suffer pain when biting down consult your dentist, it probably means the crown has been fitted too high on the tooth and this can be easily rectified.
As has already been mentioned, porcelain and ceramic crowns can be chipped. If the chip is small a composite resin can be used to repair the crown. However if the damage is substantial the crown may need to be replaced.
There is also a risk of the crown becoming lose or falling off. the cement fitting the crown can sometimes wash off, this can not only result in the crown feeling lose but also there would be a risk of decay to your underlying tooth, if your crown starts to feel lose consult your dentist immediately. If a crown completely falls off this is usually due to an improper fit or not enough cement. Adhesives for crowns can be bought over the counter however you should make an appointment to see your dentist, they may be able to re-cement the crown or another will have to be fitted.
In extremely rare cases a patient may find they are allergic to the metals or porcelain used in their crown. If this is the case other alternatives may be found but this would be an exceptional circumstance as metal allergies are rare.
Crowns can last anywhere between 5 and 15 years. The lifetime of a crown generally depends on the amount of wear and tear the crown is subjected to. Good oral hygiene is essential and chewing on anything other than food should be discouraged as well as refraining from opening packages with your teeth.
A crown should be treated as a normal tooth as there is an existing tooth underneath the crown which can still suffer from decay or gum disease even though it is covered. Therefore good oral hygiene must be maintained and regular visits to the dentist must be kept.