What is a Crown?

The Natural Crown:  "The part of a tooth that is covered by enamel and projects beyond the gum line."

The Dental Crown:  "The artificial substitute for the natural crown of a tooth."

A crown, which is sometimes called a "cap" or a "jacket," is a new protective outer covering for your tooth.

A Sample Case

Click here to see a close-up before-&-after picture of upper front crowns.

When is a Crown Needed?

A crown can be used in many different ways to help improve your dental health.  It's one of the most versatile treatments in dentistry!

A crown can...

• STRENGTHEN a compromised tooth (that is a tooth which is mostly made up of filling material),

• REPAIR a broken or cracked tooth,

• PROTECT a tooth that has had a root canal,

• BEAUTIFY a tooth by renewing its,

  • shape

  • color

  • size

  • position

  • angle

Crowns have more complex uses too!  They are used to...

• support fixed bridges,

• support removable partial dentures,

• restore the height of your bite in one location or even in your whole mouth (full mouth reconstruction),

• treat large cavities,

• replace large or damaged fillings,

• and more!

Types of Crowns

There are three main classes of crowns:

1. Porcelain* crowns with an inner metal lining,

2. Porcelain crowns with no metal,

3. Metal crowns.

*Note: Porcelain may be substituted with a less desirable resin or plastic material.

The most commonly used crown is type 1.  It combines both beauty and strength for long-lasting function.

Type 2 crowns are often used on front teeth where esthetics are more important.  Since front teeth do not absorb high chewing pressures like back teeth, front crowns may often be made without any metal.  Because of its translucency, this type of crown can mimic enamel more closely and is the most natural looking type of crown.  It is often called a porcelain jacket.

Type 3 crowns are rarely used nowadays.  Although they were once popular in the 1970's and before, they just don't meet the esthetic standards of modern times.

The Different Metals in Crowns

Since the most commonly used crown is type 1 (porcelain fused to metal) it is important to know about the different metal choices.

There are four different types of metals:

1. Non-precious (metal alloys, stainless steel color)

2. Semi-precious alloy (54-62% gold alloy, "white gold")

3. Precious alloy (89-92% gold alloy, yellow gold color)

4. Captek (97% gold composite - not an alloy, bright warm gold color)

1.  Non-precious alloys are made of low-cost metals and have been in use for many decades.  They are more difficult to cast (shape) than softer precious metals and therefore offer a less precise fit.  Non-precious alloys also tend to oxidize over time (similar to rusting) which darkens their color even more and can even stain and "tattoo" the gums.  On rare occasion, some people have had allergic reactions to the nickel in the alloy.  Although many insurance companies cover only this type of metal in crowns, Glendale Dental Arts strives to deliver higher quality treatment by providing the option of choosing more biocompatible and attractive metals, or no metal at all.

2.  Semi-precious metal offers a balance between esthetics and strength at a lower cost than precious or Captek.  It resists oxidation, it casts more accurately than non-precious metal, and it is a very commonly chosen option.  But it cannot provide the warmth and beauty of gold-lined porcelain crowns.

3.  Precious metal offers the most precise fit, the most biocompatible alloy, and the warmth and beauty of yellow gold.  Of course, it is more costly than metals with less gold content.

4.  Captek uses the newest technology to provide the most extreme combination of strength and esthetics even surpassing the qualities of precious metal alloys!  Captek is not an alloy.  It is formed using capillary casting technology which provides its exceptional characteristics.  Due to porcelain's translucency, Captek crowns are truly the most beautiful metal-based crowns and are highly recommended for all areas of the mouth, front or back.  For more information see www.captek.com.

Crown Margins

The margin of a crown is the edge where the crown ends and the tooth starts.  Margins are an important aspect of a crown's beauty, health, and lifespan.  But there is not one type of margin that works best in every situation.  The decision on which margin to choose for your crown will be based on many factors and is best made with the help of your dentist.

The most common type of crown, the porcelain fused to metal crown, can be made with three different types of margins:

• Standard - with a combination metal-porcelain margin,

• Metal margin - with a thin metal collar,

• Porcelain margin - with no metal showing (metal hidden internally).

How are Crowns made?

Crowns require at least two appointments to complete.

During the first appointment the tooth is prepared by removing any defective fillings, decay, and shaping the tooth.  Then an impression (a mold) is taken of the prepared tooth.  And finally a custom, tooth-colored temporary plastic crown is made and placed on your tooth.  All these steps usually take between 1 and 2 hours.

The impression is sent to the laboratory which usually requires 10 days to construct the permanent crown.  Here is a summary of the many technique-sensitive steps involved in the construction of a custom crown:

1. Stone models of your teeth are created from the impressions.

2. The inner metal lining (the coping) for the crown is formed with wax directly on the stone model of the tooth needing the crown.

3. The wax coping is then imbedded into a liquid cement (called investment), and the cement allowed to harden.

4. The investment is then heated in an oven to 1200° F which melts the wax away, leaving a void in the investment that represents the coping.

5. A piece of the chosen metal is then melted and force-poured (cast) into the void in the investment.

6. The metal is allowed to cool and harden.  It is then removed from the investment, refined, and polished.

7. Porcelain is then baked onto the metal coping in layers until the new tooth is formed.

8. Finally the porcelain is colored to match your teeth and glazed to a high polish.

9. The fit and the bite of the new crown are adjusted on the original stone models.

On the second appointment, the new crown is fitted and adjusted to fit perfectly in your mouth.  When both you and your dentist are satisfied with the look and feel of the new crown, it is cemented into place.