What Is a Crown?

          A crown-sometimes called a ''cap"-is a tooth-like covering placed over a carefully prepared existing tooth. Used to strengthen, restore or improve the appearance of your natural tooth a crown is placed on an individual tooth much like a thimble over your finger. One of the most common is to support the tooth when there is no longer sufficient tooth structure left to place a filling.

           There are several ways of restoring teeth, the most common being a filling or bonding. Crowns are used to strengthen a tooth and repair badly decayed, broken, severely discolored, misaligned teeth or capped the tooth after root canal treatment. Crowns may also be used to protect the structure of a tooth that is fractured or broken. Crowns completely cover teeth, restoring them to their natural color, size, shape, and function. The location of the crown in the mouth usually dictates the type of material used. The tooth under the crown is reduced in size. The crown will be permanently cemented over the reduced tooth. While you are waiting for the permanent crown to be fabricated, your dentist will provide you with a temporary one to wear. Crowns have a much longer life span than bonding, resist stains better, hold their color and resist chipping and cracking. Crowns, however, take longer to prepare than bonding and are not reversible. Your dentist can recommend which type of restoration is best for your particular situation.

            If the tooth is severely decayed, little tooth structure remains or after root canal treatment for the back tooth, it may be necessary to place a metal post into the tooth to support the crown. If this is the case, root canal therapy will be performed.

The reasons for do crowns?

•  Restore after root canal treatment – To protect remaining tooth structure
•  Aesthetic Reasons - Badly discolored and misshapen teeth
•  Restorations (Fillings) Which Just Don't Stay In - Sometimes there is too little tooth remaining for a restoration to  successfully resist dislodgment
•  Cracked Teeth - Teeth may have microcracks that cause sensitivity when exposed to hot and cold temperatures, pressure, and air stimulation.  The full coverage afforded by crowns often relieves these symptoms while reinforcing the tooth

How long do crowns last?

          It depends on your oral hygiene and habits. However, with good oral hygiene and supervision most crowns will far out last that time frame. Bad habits, such as grinding and clenching your teeth, chewing ice, and/or fingernail-biting may greatly reduce the life of your crowns. In addition to visiting your dentist and brushing twice a day, cleaning between your teeth is vital with crowns. Floss or interdental cleaners should be used regularly to remove plaque from the crown area where the gum meets the tooth.

Types of Crowns?

•  All ceramic crowns
•  All metal crowns
•  Porcelain fused to metal crowns
• All resin crowns

• Aesthetic Reasons - Badly discolored and misshapen teeth
• Restorations (Fillings) Which Just Don't Stay In - Sometimes there is too little tooth remaining for a restoration to successfully resist dislodgment
• Cracked Teeth - Teeth may have microcracks that cause sensitivity when exposed to hot and cold temperatures, pressure, and air stimulation. The full coverage afforded by crowns often relieves these symptoms while reinforcing the tooth

Why crowns and not veneers?
       Crowns require more tooth structure to be removed, hence, they cover a larger portion of the tooth than veneers. Crowns provide protection around the entire tooth and are generally indicated for teeth that have sustained significant loss of structure or have a high risk for fracture. Crowns may be placed on natural teeth or dental implants.

How long do crowns last?
       It depends on your oral hygiene and habits. On average, crowns last approximately 6-9 years. However, with good oral hygiene and supervision most crowns will far out last that time frame. Bad habits, such as grinding and clenching your teeth, chewing ice, and/or fingernail-biting may greatly reduce the life of your crowns. In addition to visiting your dentist and brushing twice a day, cleaning between your teeth is vital with crowns. Floss or interdental cleaners should be used regularly to remove plaque from the crown area where the gum meets the tooth.

Procedure
       Most crown preparation visits are reasonably long. The entire procedure usually takes two visits.

       A few radiographs may be necessary to check the roots of the tooth receiving the crown and to evaluate the surrounding bone level. If the tooth is vital, the area will be anesthetized with a local anesthetic. The tooth receiving the crown will be recontoured by removing a layer of tooth structure from the chewing surface and the sides. The amount removed depends on the particular type of crown used (generally between 1 to 2mm). Once the tooth has been prepared, an impression is taken. The crown will be fabricated using this impression. A shade (or color) is then selected for the crown.


       Your dentist will then fabricate a temporary crown to cover and protect the prepared tooth while the permanent crown is being made. The temporary will not be as strong as the permanent crown; it will be attached using a temporary cement so that it can be removed once the permanent crown is back from the lab. It's a good idea to avoid chewing sticky foods while the temporary crown is in place; they often become dislodged.


       At the second appointment, the temporary crown is removed and the fit of the new crown is checked. If the occlusion (bite) is acceptable and the color has been matched correctly, the new crown is then cemented into place using a permanent cement.