Our natural teeth consist of
the root and the crown, which connect at the neck or dentino-enamel junction. Enamel covers the crown of the natural tooth,
and protects inner surface of the tooth –dentin and the nerve with vessels-pulp, from outside bacteria. Generally, in
a healthy dentition crown, part of the tooth is what you see and the root is what holds the tooth inside the bone. Restoration,
which substitutes the natural crown of the tooth to its anatomical and functional state is also called crown. Many people
outside dentistry call it ‘cap’.
There are many situations,
why crowns can be the only right solution for the patient. Here are some examples:
- Any tooth that had Root Canal Treatment needs a crown.
When the root canal
treatment is performed on the tooth, along with the nerve, all blood vessels are removed from the tooth. The tooth stops to
get needed nutrition and becomes brittle, and eventually will break if not restored properly.
- If more than, half of the tooth structure has been lost due to decay. (Sometimes the onlay or partial crown can be
done instead of the crown.)
- If teeth were worn down due to Bruxism, crowns could be the only option.
- Crown may be needed to give necessary support to the removable partial denture.
- During comprehensive full mouth, rehabilitations when we have to increase vertical dimension (open bite).
- Cosmetic considerations are one of the reasons to put crowns.
- Crown may be a part of fixed bridge, which is used to restore missing teeth.
|Tooth Preparation for All Porcelain Crown
In a couple of weeks, your
custom made crown will be returned from the lab. When you come for your next visit, doctor will remove your temporary crown
and will check the fit of you new restoration:
- Margins of the crown should cover all prepared surfaces of the tooth and sit tightly on the tooth structure
- The new crown should have a tight contact with adjacent teeth. The floss should be able to pass through with a slight
pop sound. This will prevent you from the food stocking in between the teeth.
- The height of the crown should be corresponded to other teeth and should not interfere with the bite
- Cosmetic appearance will also be checked, including shape, shade and position.
After all necessary
adjustments are done the crown is ready to be cemented in.
How crown is done?
Crowns can be made from different
materials, utilizing different technique and methods. However, the main principals remain the same. First, the tooth has to
be prepared to accept the new crown. The doctor using special diamond burs does the preparation. About 1to 2 mm (depending
of the type of the crown) of tooth structure is removed. The tooth is cone shaped. The doctor places the finishing line on
the prepared tooth, depending on type of restorations and given conditions. Many patients mistakenly think that the crown
has to end under the gum line. It is true that in most cases the margins of the crown are placed under the gum for the cosmetic
reasons. However, the rule is, that the margin of the crown has to end at the finishing line placed by the doctor, and if
the cosmetic is not major consideration, supragingival (above the gum line) placement of crowns is more desirable.
After the preparation is completed,
doctor will place the retraction cord or special retraction paste between the gum and the tooth for a few minutes. Cord will
push the gum away from the tooth to allow impression material to flow in for perfect impression. Impression of opposing teeth
and bite registration (if needed) are done, and case is ready to go to the dental lab. Before you leave, the doctor will make
the temporary crown and fix it with temporary cement.