What is a Crown?
Teeth that become decayed or fractured and require extensive restoration may require a cap or a crown. This is to repair or protect the tooth and enables you to eat and function normally. Generally a crown is placed over a tooth, to protect the tooth structure from further destruction. Once gross decay of tooth structure has occurred it may not be feasible to do a normal tooth filling, as there will not be adequate tooth structure to retain the filling.
When is a crown generally used?
A root canal treatment (RCT) treated tooth is usually protected with a crown, because during RCT the vital structure of the tooth (pulp) is removed, making the tooth brittle and liable to fracture. A crown may also be used to restore fractured teeth, or cover badly shaped or discolored teeth. Thus a crown is a restoration that covers or “caps” a tooth to restore it to its normal shape and size, strengthening, and improving the appearance of a tooth. Crown is also used during bridge placement, dental implants, and sometimes to achieve parallelism of the teeth during castmetal insertion.
To prepare the tooth for a crown the thickness of the crown (about 1.5 - 2 mm) is reduced from the tooth so the crown can fit over it. An impression of the teeth and gums are made and sent to the Dental Lab for the crown fabrication. A temporary crown maybe fitted over the prepared tooth until the permanent crown is ready. On the next visit, the dentist removes the temporary crown and cements the permanent crown onto the tooth with the help of dental cements. Sometimes a trial fit in of the crown is also done. To achieve a natural appearance a number of factors are considered, such as the color, bite, shape, and length of the natural teeth. Any one of these factors can affect the appearance.
A crown maybe prepared from cast metal or porcelain. A porcelain crown is more aesthetic than cast metal, for it has the color and translucency of the natural tooth. A tooth colored acrylic facing is usually made on the cast metal crown for aesthetic reasons, but this undergoes abrasion, discoloration and material decay over a period of time and so will usually require refacing after two to three years. A porcelain crown is superior to a cast metal crown, as it does not undergo abrasion or discoloration. To prevent damaging or fracturing of the crown it is better to avoid chewing hard foods or other hard objects, and teeth grinding. Proper brushing with regular toothbrush, proxibrushes, dental floss, etc., is a must after crown fixation. Extra care and time should be given for maintenance and the cleanliness (hygiene) of the mouth.