A crown is a fixed indirect restoration used to cover the tooth to restore its shape and size, strength, and improve its appearance.
What Is A Crown?
A dental crown is a type of cap that is placed on a tooth to modify the appearance of the natural tooth or to help protect the remaining structure of a tooth from fracture. Teeth that are severely discolored, misshaped or broken down benefit from full coverage restorations. This gives the appearance of an ideal tooth even though the original tooth was in poor shape structurally or esthetically. Structurally, a crown allows for dissipation of occlusal forces down the long axis of a tooth. It also eliminates excessive lateral pressure that is exerted during chewing on the walls of a tooth. Dental crowns are commonly used in full mouth reconstruction to provide a patient with a more natural bite and to replace worn natural crowns. These restorations allow the patient to chew and function more comfortably with the benefit of a beautiful smile.
Natural tooth shade or shape modification can be easily accomplished with a crown because it is fabricated in a dental laboratory under controlled conditions. Some dental offices offer same day crowns, which are fabricated by an in-house, three dimensional milling machine. The restoration is designed by a dentist with the help of a computer and milled specifically to fit the prepared tooth. Dentists are able to correct alignment of a natural tooth and modify the shape and shade to match the rest of the teeth.
Another common reason for crowning a tooth is to protect a weakened, heavily restored tooth with little remaining tooth structure from fracture. A tooth can be weakened or esthetically altered by a traumatic event, placement and replacement of fillings, normal wear, extensive decay, large fillings, fracture, aging, and defects within the tooth structure caused by normal or abnormal wear and tear.
For root canal treatment to be completed a large opening has to be made in a crown to gain access to the pulp chamber and canals of the tooth. Due to removal of large amount of supporting dentin these teeth become weak and prone to fractures. Root canal teeth also become brittle over time, which is why crowns are recommended after endodontic treatment is completed. This prevents an unexpected fracture and loss of a tooth. Another important reason to crown a root canal treated tooth is to prevent leakage of bacteria, which could re-infect the tooth if left unchecked. A well fitting crown creates a tight seal, which prevents microleakage.
Even though a dental crown in most cases does cover the majority of the tooth, good oral hygiene is crucial for its long-term success. Crowned teeth are at even greater risk for recurrent decay. This is due to potentially irregular margin where the transition occurs from a natural tooth to the crown margin.
Fabrication of a crown by a laboratory takes about two weeks. Crowns that are milled in the office are usually done in less than an hour. After fabrication, a crown is fitted, adjusted and permanently cemented on to provide ideal esthetics and function. Life span of a crown can vary however, on average a crown will last about fifteen to twenty years.
Purpose Of A Dental Crown
Below is a list of benefits of a dental crown:
- Replace missing tooth structure
- Improve esthetic appearance by covering the existing tooth all the way to the gum line
- Provide a good seal for a root canal treated tooth
- Avoid that sunken-in appearance caused by missing teeth usually present in the older population
- Stabilizing a specific area of the dental arch to give a more youthful appearance
- Crowns are crafted and designed to perfectly fit and blend with your natural teeth
- Shade selection allows an ideal esthetic result
- Shape is matched to surrounding teeth which makes the cemented crown seem as a natural unaffected tooth
- Protect a tooth with a large existing filling from breaking
- Protect a tooth from fracture after root canal treatment is completed
- Vertically stabilizing the bite between the upper and lower jaw, especially in cases of severe tooth wear
Cost Of A Dental Crown
The cost of a dental crown can vary greatly across the country. Prices can range from about $700 to as much as $1800 and sometime more. Generally, cost of a crown tend to be higher on the coasts and lower in the midsection of the country. Dental crown prices are higher than cost of a filling for several reasons:
A dental crown is considered a long-term restoration with a life span of about 10-20 years. The length of time that a crown will last is dependent upon several factors, which include:
- Quality and frequency of oral hygiene (how often and how well teeth are brushed and flossed)
- Caries rate (at what frequency cavities may form in the oral cavity)
- How precisely the crown fits on the tooth (more precise fit, less chance of an irregularity that may result in new decay)
- Area in the mouth where the crown is placed (front teeth are usually easier to maintain than back teeth)
- Crowns on molars and premolars tend to be put through a lot more stress over a period of time as compared to the front teeth
Several factors can dictate potential cost. A dental crown fabricated by a general dentist will on average cost less than a crown fabricated by a prosthodontist. The cost of a crown can also depend on which part of the country you live in, on type of materials used to make the crown, experience of the lab technician who will be fabricating the dental crown and the time spent fabricating it.
Different Types Of Dental Crowns
Our teeth are made up of the outer shell of tooth enamel and an inner portion of dentin. Structurally, enamel is very brittle without the support of dentin. As we age our teeth can become weaker due to structural changes. Parafunctional habits such as clenching or grinding of teeth, trauma, and normal and abnormal wear are some of the more common reasons for more compromised teeth. Over time teeth can erode, develop cracks, cavities and wear down which can weaken the overall tooth structure even more. The best way to deal with a compromised, weaken tooth is by covering it with a crown. A dental crown is a restoration, which encircles and partially or completely covers the tooth. The crown will keep the tooth structure intact even under great biting forces. Over the years there have been several crown designs and various materials used. For the purpose of our discussion we will focus on three different types of crown designs:
- All Metal
- All porcelain
- Porcelain fused to metal crowns
All Metal Crowns
Dental crowns made completely out of metal have been used for decades. They vary from crowns made out of base metal alloy to crowns made out of gold. These crowns are very strong and durable. Base metal crowns are usually the least expensive crowns available. The fit of base metal crowns is acceptable, but does not compare to the fit of a crown made out of gold or porcelain. They also tend to corrode over time.
Gold crowns are more inert and stable. Gold alloy crowns are softer and provide an excellent fit. These crowns usually have the best fit out of all different types of crowns although today, porcelain crowns are almost to the same standard. A well fitting gold crown is durable and can outlast all other crown designs. The tooth requires less preparation or reduction when compared to a porcelain crown. Another benefit of a gold crown is that it doesn’t cause excessive wear on opposing natural teeth, which is the case with porcelain. The only disadvantage of a gold crown is that it is either yellow or white in color. This makes them less popular than other more aesthetic crowns. They are still commonly done in the back regions of the mouth where they are not as noticeable. Cost of gold crowns can vary based on the current price of gold. With an increase price of gold, the cost of a gold crown can be as much and even more than a cost of a porcelain crown.
All Porcelain Dental Crowns
All porcelain dental crowns are tooth colored crowns without any metal substrate. These crowns are highly esthetic and can be fabricated for teeth in anterior (front) and posterior (back) regions. Different porcelain materials are used for crowns requiring more esthetic appearance than for crowns that need to withstand the stress created by forces during chewing. With the advancements made in the strength of porcelain materials, and crown fabrication techniques, porcelain crowns can be comfortably used on any tooth in the mouth. Most porcelain crowns that are made today are milled from a block of porcelain. It is a form of 3-d printing. This technique reduces or eliminates any structural imperfections that used to occur during previous fabrication methods. The main advantage of an all porcelain crown is superior esthetics. The color and translucency of these crowns is excellent, and esthetically, porcelain crowns can look better than natural teeth. In addition, a porcelain crown can be stained to match the color of the rest of your teeth. Other advantages include strength, the fact that the restoration is metal free, and excellent color stability throughout the life of the crown.
What would be considered a minor disadvantage is that the tooth has to be reduced or shaved down slightly more, as compared to reduction for a metal crown, to provide room for porcelain. Porcelain crowns perform well when certain parameters of minimum and maximum porcelain thickness are followed. If there is not enough tooth reduction, the crown will be too thin and it can crack. When recommended guidelines are followed porcelain crowns provide a strong and very durable restorative option.
Porcelain Fused to Metal Crowns
Porcelain fused to metal dental crowns (PFMs) are tooth colored crowns with a metal substrate. These crowns are esthetic and usually recommended for teeth in posterior regions. The porcelain surface provides an aesthetic appearing crown. The metal substructure provides a good marginal fit of a metal crown as well as structural support for the overlaying porcelain. These types of crowns work well in high stress areas where aesthetics is not the primary concern. Even though these restorations are tooth colored, they usually lack translucency, or depth often seen in teeth of younger individuals. With advances in porcelain strength and excellent esthetic appearance, all porcelain crown have become more popular than PFM crowns. However, there are still dentists that prefer to place porcelain with metal crowns in the posterior regions of the mouth.
Dental Insurance and Crown Coverage
Due to high cost of crowns, many of us rely on dental insurance to cover a portion of the cost of treatment. Most dental insurance plans will cover a portion of the cost of a dental crown. Crowns are classified under major dental work. With most dental insurance plans dental crowns are covered at 50 percent although, the coverage can range from 50 to 100 percent. Usually the more expensive dental plans will cover 80 and up to 100 percent of the cost of the crown. You may consider choosing a dentist that is a participating provider with your insurance network to obtain better coverage on dental work. Check with your dental insurance company to get more information.