Crowns and bridges are major restorations for cracked and infected/decayed teeth with compromised enamel. They can also be used for esthetic purposes to reshape teeth. Crowns typically cover all of the tooth surfaces (mesial, lingual, buccal/facial, incisal/occlusal, distal) like a cap covering all sides of the lip of a water bottle. Typically, crowns are used to restore the function of teeth after a root canal has been done or after severe trauma to the enamel (from a fall or a basketball to the face). Because they cover all surfaces of the tooth, crowns can be shaped, shaded, lengthened/shortened, or widened to fit the space between adjacent teeth. Aesthetically speaking, crowns can cover gaps, change the look of previous teeth to match the ones next to it an do so all the while creating protection for the affected tooth.
Crowns can be made of various materials of varying hardness.
1. Metal: Metal crowns are made of different types of alloys. Metal crowns generally refer to either precious or semi/nonprecious metals. Precious metals is typically gold (see "Gold" below). Semi/nonprecious metal is the more common reference. They are the most basic crown material with the basic function to protect the natural tooth with no consideration to aesthetic as they are typically used for molar teeth (where they are not often seen).
2. Porcelain-Metal: The most commonly used material is the porcelain-metal variety (porcelain material covering a metal crown). They combine the supportive benefits of a metal crown (less likely to break than all-porcelain from sharp impact) with the aesthetic benefits of porcelain to maintain a natural look. The porcelain layer will typically cover most of the tooth except for one small strip hidden on the lingual surfaces (facing the tongue). This layer may chip over time if the crown is not taken care of.
3. All-Porcelain: Porcelain crowns are a step above in terms of esthetics. Overtime porcelain-metal crowns may chip or gums may recede to show the metal underneath. All-porcelain crowns are a solution for this issue. There is no metal to speak of and if they chip, the layer beneath is the same color and indistinguishable from natural teeth. Ironically, all-porcelain crowns can crack under immense pressure as well because of the lack of added support from a metal under layer. They are generally not recommended for molar teeth for this reason.
4. Zirconia: An alternative to the all-porcelain for molar teeth is a special type of porcelain material called zirconia (named for its "diamond hardness"). Zirconia is one of the toughest crown materials that exists in the dental field. They can withstand even pressure from nighttime grinding. Zirconia crowns may be also be known as BruxZir crowns (a specific brand of zirconia)
5. Gold: Gold crowns have become increasingly rare to the point that some insurances have even begun to stop covering them. In the past, they were popular for molar teeth where constant chewing and chomping down could benefit from such a material. Due to gold's malleability, the crowns can change and adjust their occlusal shape to compensate for opposing teeth pressing into them. Eventually the cusps will settle into a semi-permanent shape based on the chewing habits of the individual with the crown. Present day, gold crowns are mostly used for cosmetic purposes, like "dental jewelry" because of their shine and color.
The Procedure: For crowns to be placed, the teeth or tooth to be repaired must be shaped and/or cleaned up of decay (like sanding down surfaces before you glue them together)- this is called the preparation process. Part of the preparation may be the addition of a post and core for added support where a large amount decay had been. Typically, permanent filling material does not provide much structural support. On the same day as the impression, a metal post will be inserted and permanently sealed into the core of the tooth. The post will typically fill up the root canal and the pulp cavity. The post will be shaped as part of the preparation process. After the tooth is shaped correctly, the Dr. Lee will take an impression of the prepped surface. The impression will be sent to a lab specializing in fabricating crowns with specific instructions from Dr. Lee on how the crown should be shaped or shaded. Crown in hand, Dr. Lee will permanently cement the crown in and adjust it to each individual's natural bite on the same day.
Before You Come In: You will be numbed for the preparation. It is recommended that you eat beforehand as numbness can last up to two hours. Please consult with Dr. Lee to make sure you do not require additional treatment for the tooth such as a root canal or invisalign which can be affected after the crown is placed.
What You Can Expect Afterwards:Although crowns are permanent fixtures and can last on average approximately five years to twenty years, they require maintenance. Avoid trying to crack lobster shells, crab shells, walnuts or other similarly hard objects with the crown. Keep your oral hygiene up to avoid periodontal disease and gum recession which would uncover your unprotected roots for bacteria to eat away at. Clean the crown as you would a natural tooth.
Discoloration and imperfections were corrected with three E-Max (all-porcelain)crowns.
Discoloration, chips and calculus buildup on the third, fourth and fifth teeth from the left on the top arch noted.
Model of a prepped tooth.
Note: To be restorable, there must be enough tooth structure left to support a crown.