Tooth Replacement Options

Bridges

Tooth Replacement with Tooth Supported Bridges

The next method of tooth replacement is a tooth supported bridge. In this method, the teeth adjacent to the missing tooth are ground down and a bridge is placed. This bridge may be 3 or more teeth. The two caps on the teeth are called abutments and the cap connected to the abutment teeth is called the pontic. Although bridgework has served patients well for decades and is usually preferable to a removable partial denture, they have their limitations including potential failure of the abutment teeth.

A natural tooth has two parts, the crown of the tooth is the part you see, and the root of the tooth is the part that is in the bone. A tooth supported bridge only replaces the crown and not the root of the root. As a result, the bone where the root used to be will start to atrophy or wither away. When you lose a tooth you lose part of your jaw bone as well.

Although the studies report various success/failure rates for tooth supported fixed bridges over different time spans, many studies appear to report similar results for periods of 10-15 years.

Various studies report the mean life span to be about 10 years, with decay and root canal problems the main causes of failure. Studies also report that a significantly higher percentage of abutment teeth (the teeth that are ground down to support the missing tooth) require root canal therapy compared to nonabutment teeth.

Often the failure of tooth supported fixed bridges result in loss of abutment teeth and the need for additional abutment teeth and pontics in the replacement prosthesis.

Failure of tooth supported bridges falls into two categories, biologic and mechanical:

    Biologic Failures:
  • Caries-(tooth decay)
  • Periodontal disease (gum disease)
  • Endodontic or periapical problems (root canal problems)
    Mechanical Failures:
  • Loss of retention (the bridge comes uncemented)
  • Fracture of porcelain
  • Wear of gold restoration
  • Fracture of bridge
  • Fracture of solder joints in the bridge
  • Fracture of abutment tooth or root
  • Poor foot of the bridge
  • Poor contours
  • Poor aesthetics

Let’s look at the studies concerning survival of tooth supported bridges:

  • Palmquist 1993 103 fixed bridges 18-23 years observation only 79% success
  • Lindquist 1998 140 bridges 20 years, only 65% success
  • Yi 1995 10-15 years only 70% success (8% of abutments had to be extracted)
  • Glantz 1993 15 years only 64% success
  • Hammerle 2000 5-26 years 115 bridges and 229 abutment teeth
  • 12% of abutment teeth died and needed a root canal
  • 8% of abutment teeth got cavities
  • 8% of the bridges came uncemented
  • 3% of the abutment fractures
  • Scurria 1998 combined data from 9 studies giving a total of 2761 abutment teeth observed over 3-20.5 years. The 10 year success was 85%, 15 year success 66%.

In conclusion, there seems to be agreement in the studies that:

  • Tooth supported bridges are about 66% successful for periods of 15 years.
  • The mean life of a tooth supported bridge is about 10 years.
  • Studies report abutment tooth loss ranging from 2% to 30% for periods of 8-14 years.

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