In my previous blog entry, I discussed the tooth replacement option of a full or partial removable denture. The next tooth replacement option that dentistry has to offer is a fixed bridge. Both the removable and fixed dental prostheses are what I like to consider 20th-century dentistry, in that both of these options were the only options for restoring missing teeth available to most people during that time. A fixed dental bridge is most commonly used to replace a single tooth or two adjacent teeth. As long as there is a good, solid, and accessible tooth present on both sides of the space caused by a missing tooth or teeth then a fixed bridge can be placed most of the time.
How a fixed bridge replaces missing teeth is fairly simple. The teeth on either side of the space are prepared for a crown or other type of indirect restoration. These teeth are known as abutment teeth and it is essential for them to be in good shape and anchored solidly in the bone with good root structure and a crown to root ratio of less than 1. That means that the height of the tooth or crown above the crest of the jaw bone is less than the length of the root in the jaw bone. Depending on how long the span of the bridge is, and how many teeth are being replaced, it is critical to make sure that these specifications for abutment teeth are followed if you want the bridge to function well and last a long time.
Fixed dental bridges can be made out of metal, porcelain, zirconium oxide, porcelain fused to metal or porcelain fused to zirconium oxide. Long span bridges are most predictable and durable when metal or porcelain fused to metal is used. Shorter span bridges can be porcelain if the patient does not clench or have a strong bite and is usually better if placed anterior to molar teeth. Zirconium oxide is a good esthetic and durable option to replace one or two teeth anywhere in the mouth. Sometimes a bridge called a “Maryland” bridge can be made to restore a missing single tooth in either the posterior or anterior areas of the mouth if the teeth on either side of the space are perfectly healthy with no cavities or fillings. This is generally done to conserve tooth structure. These bridges require minimal prepping or drilling and most of the time you don’t have to be numbed up when the teeth are prepped. These types of bridges are always bonded on with resin based cements.
The pros and cons of fixed bridges are as follows:
- They are fixed or glued to the abutment teeth.
- There are many choices for materials and designs.
- They are more esthetic than removable bridges or dentures.
- They chew and function very similar to natural teeth.
- They can be reattached due to cement failure.
- They can last many years before needing to be replaced.
- They are more difficult to maintain and clean under.
- They are more expensive.
- The abutment teeth can decay at the margin of the bridge leading to failure.
- Abutment teeth roots can experience fracture leading to loss of bridge.
- Not a good method of tooth replacement with uncontrolled oral disease.
In my next entry, I will discuss the final tooth replacement option in dentistry: dental implants.