What are Dental Crowns and Tooth Bridges?
Both crowns and most bridges are fixed prosthetic devices. Unlike removable devices such as dentures, which you can take out and clean daily, crowns and bridges are cemented onto existing teeth or implants, and can only be removed by a dentist.
How do Crowns Work?
A crown is used to entirely cover or "cap" a damaged tooth. Besides strengthening a damaged tooth, a crown can be used to improve its appearance, shape or alignment. A crown can also be placed on top of an implant to provide a tooth-like shape and structure for function. Porcelain or ceramic crowns can be matched to the color of your natural teeth. Other materials include gold and metal alloys, acrylic and ceramic. These alloys are generally stronger than porcelain and may be recommended for back teeth. Porcelain bonded to a metal shell is often used because it is both strong and attractive.
Your dentist may recommend a crown to:
- Replace a large filling when there isn't enough tooth remaining
- Protect a weak tooth from fracturing
- Restore a fractured tooth
- Attach a bridge
- Cover a dental implant
- Cover a discolored or poorly shaped tooth
- Cover a tooth that has had root canal treatment
How do Bridges Work?
A bridge may be recommended if you're missing one or more teeth. Gaps left by missing teeth eventually cause the remaining teeth to rotate or shift into the empty spaces, resulting in a bad bite. The imbalance caused by missing teeth can also lead to gum disease and temporomandibular joint (TMJ) disorders.
Bridges are commonly used to replace one or more missing teeth. They span the space where the teeth are missing. Bridges are cemented to the natural teeth or implants surrounding the empty space. These teeth, called abutments, serve as anchors for the bridge. A replacement tooth, called a pontic, is attached to the crowns that cover the abutments. As with crowns, you have a choice of materials for bridges. Your dentist can help you decide which to use, based on the location of the missing tooth (or teeth), its function, aesthetic considerations and cost. Porcelain or ceramic bridges can be matched to the color of your natural teeth.
How are Crowns and Bridges Made?
Before either a crown or a bridge can be made, the tooth (or teeth) must be reduced in size so that the crown or bridge will fit over it properly. After reducing the tooth/teeth, your dentist will take an impression to provide an exact mold for the crown or bridge. If porcelain is to be used, your dentist will determine the correct shade for the crown or bridge to match the color of your existing teeth.
Using this impression, a dental lab then makes your crown or bridge, in the material your dentist specifies. A temporary crown or bridge will be put in place to cover the prepared tooth while the permanent crown or bridge is being made. When the permanent crown or bridge is ready, the temporary crown or bridge is removed, and the new crown or bridge is cemented over your prepared tooth or teeth.
How Long do Crowns and Bridges Last?
While crowns and bridges can last a lifetime, they do sometimes come loose or fall out. The most important step you can take to ensure the longevity of your crown or bridge is to practice good oral hygiene. A bridge can lose its support if the teeth or bone holding it in place are damaged by dental disease. Keep your gums and teeth healthy by Brushing with fluoride toothpaste twice a day and flossing daily. Also see your dentist and hygienist regularly for checkups and professional cleanings.
To prevent damage to your new crown or bridge, avoid chewing hard foods, ice or other hard objects.
Full cast gold crown.
Full cast gold crown.
Teeth around the space are prepared.
The bridge is mounted and adjusted for fit and comfort.
The bridge is cemented into position.
Zirconium crowns and bridges are so strong they can be used anywhere in the mouth. Zirconium crowns can withstand the biting pressure of the front teeth as well as back teeth grinding. The look of zirconium crowns and bridges is so close to natural teeth that it is hard to tell the difference and it is this quality which makes it very useable within dental work. Zirconium crowns can be fixed using traditional dental cements. Zirconium crowns have quickly become the preferred material for dental crowns. Zirconium is a very strong substance that can endure wear and tear of everyday use. When looking at Zirconium crowns from an aesthetic point it is clear and very similar to a natural tooth and reflects light the same way. This may be important if your new crowns are on the front of your mouth and it is particularly relevant in cases where the crown will be seen next to the natural teeth. Porcelain is the conventional material used for the new crowns however, Full porcelain can chip or break. This is overcome by making the crowns from the metal, in this case metal zirconia, then merge the porcelain on the outside. Zirconia metal gives the strength while the porcelain gives the appearance of a normal tooth. Zirconium crowns allow light to pass as a normal tooth would and that gives a natural look, unlike other metal cores that are block the light.
Zirconium crowns won’t corrode and the normal black gum line that you can see around a porcelain fused metal crown, won’t happen because of the strong ceramic material used. Also the normal too hot/cold sensations you can feel with other crowns does not normally occur because of the lack of electrical conductivity.