What are DentalCrownsandToothBridges?
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 Ceramiccrowns 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
- 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.
What types of crowns are available?
All Ceramic Crown – Cosmetically these crowns look the best and are usually indicated for front teeth. These crowns have no grey metal inside them, so if in time the gum recedes, there will be no grey metal margin on show around the crown. An example of this would be Zirconium containing crowns that have a tooth colored Zirconium core with porcelain on top.
Metal Ceramic Crown – These crowns have a metal core inside and porcelain bonded to their outside. The core inside can be made from precious, semi-precious or non-precious metals and it provides the strength behind these crowns. However the porcelain bonded to the metal cores is not very strong and from time to time can fracture.
Metal Ceramic crowns are usually used on back teeth although some dentists use them for front teeth as well. The aesthetics of Metal Ceramic crowns is not as good as all ceramic crowns, however their strength is higher.
All Zirconium Crowns – These crowns look yellow/brown in color and are usually used for back teeth. These crowns have no porcelain, so the risk of fracture is less than all ceramic and metal ceramic crowns but as they have no porcelain, their aesthetics is compromised compared to all ceramic and metal ceramic crowns.
In terms of tooth reduction these crowns need minimal tooth reduction and are less damaging to the tooth as less tooth tissue is removed for their construction. All Zirconium crowns are ideal for situations where gold crowns historically have been the best option.
Gold Crowns – These crowns are the strongest crowns available but are poor from an aesthetic point of view. They are usually used for back teeth especially in people who suffer from grinding and clenching habits.Gold crowns can be made very thin and as such need minimal tooth reduction and are less destructive of tooth tissue compared to metal ceramic and all ceramic crowns.
What is the procedure for having dental crowns?
- Assessment of the tooth clinically and with an X-ray to ensure the roots of the tooth are sound and the tooth is vital. Preparation of the tooth for a crown and taking impressions for the lab to construct the crown.
- Fit of the final crown once it’s returned from the lab.
What types of Bridges are available?
Dental Bridges are false teeth that replace missing teeth by anchoring to one or two of the neighboring teeth. The false tooth is known as the pontic and the anchoring teeth are known as abutments. They are an alternative to dental implants for whose patients who do not wish to have surgery.
There are different types of bridges.
- Porcelain fused to metal bridges