Crowns or Fixed Prosthesis

A crown is a covering that goes completely around a tooth. They can be made from various materials but usually from pure porcelain that is fused to a metal substructure, often gold or from porcelain only.

Crowns are used to support a tooth and decrease the tooth’s chances of fracturing. Gold alloys have been used for many years for the construction of crowns or fixed bridges. They provide excellent, strong, long-lasting service.

Crowns

Crowns are used to support a tooth and decrease the tooth’s chances of fracturing. This is especially true when a tooth has been heavily filled or root filled and the remaining tooth is weak or there is not enough tooth structure left to hold in a filling. Crowns are also used for aesthetic reasons when we need to change the shape or colour of a tooth.

The length of time it takes to prepare a tooth for a crown depends on the difficulty of the situation. Usually a minimum of one hour is required in the dental chair. An impression (mould) is taken of the prepared tooth and sent to a Dental Technician who takes approximately two weeks to construct the crown. A temporary crown is made of plastic and is placed on the tooth for this time, so that you can eat properly and the tooth looks normal.

It takes approximately 30 minutes to cement in the new crown on the next visit.

Generally a crown fails not because there is something wrong with the crown, but usually due to decay in the tooth around the crown or the rest of the mouth changes (such as teeth get darker, but crown stays the same) and this makes the crown stand out or the gum recedes around the crown.

Depending on the situation a crown should last for approximately ten years, if the supporting tooth stays healthy. (see Tips on Oral Hygiene section) It is important though that you maintain regular dental check ups over this time, because if something starts going wrong with the crown it can more easily be corrected at an early stage.

 

Crown

Alloy Crowns

Two major types of alloys are now available:
High Noble Metal, mostly gold, also palladium or silver and occasionally platinum, zinc or copper.
Base Metal, mostly nickel also chrome or cobalt and other base metals.
All of the above metals are used either as the sole constituent of a crown, or as a base on which porcelain is fired (baked). Most people have no biologic response to the base metals. If you have known allergies to metals, please tell us. We usually use high-noble metals. The cost of these is somewhat higher than base metals.[/toggle]

Porcelain Only Crowns

Pure porcelain crowns are now being used more extensively for aesthetic reasons.