Bridges are restorations cemented in place and used to replace missing teeth. This is just one of several options for replacing missing teeth, with implants and dentures being the others. The material options for bridges is the same for that of crowns, however the longer the span of the bridge (space between abutment teeth), the more flex it has and the higher the risk for porcelain fracture. Bridges work best when there are solid teeth on either side of the missing tooth. Depending on the quality of the abutment teeth (teeth used as anchors for the bridge), and the number of pontics (portion that replaces a tooth) the preparations on abutments may be minimally invasive (similar to a veneer), or more invasive, like a crown. The abutment teeth may be natural teeth or implants. The key for longevity of bridge work is cleanliness, and strong abutment teeth.
When deciding on bridges it is very common for people to decide on a bridge over an implant due to cost and often better insurance coverage for the bridge. I caution against this as it is not uncommon for another tooth to be lost when a bridge finally does fail, and the future replacements cost are often more than if an implant was done from the start.
Forces also need to be taken into account when deciding on a bridge. You have to remember that for each tooth being replaced, all that force is now added to the anchor teeth. So if two teeth are being replaced using two anchor teeth, those teeth are now going to experience double their normal forces which can severely compromise their life span.
5 Unit Bridge Replacing 2 Teeth
As mentioned above, when a bridge fails it can often take another tooth with it. This patient had an existing 3 unit bridge and one of the anchor teeth rotted out underneath. In order to preserve this patient’s smile the old bridge was removed, bad tooth extracted, and new bridge prepared. As the new bridge was to replace two missing teeth, the bridge was extended to anchor onto two teeth in the back and one in the front in order to distribute the forces as much as possible. Final result was a great smile.
The photos show the process from initial bridge to final bridge. In the prepared bridge photo the dark area on the gums is the decayed tooth that was removed right after the photo was taken. You can also see in the photos the extent of bone loss from the missing teeth by how high up the bridge has to go. Fortunately it does not show when smiling.
5 Unit Implant Supported Bridge With 3 Implants
When multiple teeth are missing in a row a bridge anchored on natural teeth may not work very well. An option available is to do a bridge over multiple implants which can significantly reduce the cost of replacing each individual tooth with individual implants. For this case, the patient had a partial denture but wanted something fixed in place. To achieve this, implant placement was chosen (span to long to provide a long lasting bridge on natural teeth). Three implants were placed and a 5 unit bridge fabricated to be cemented to them. The gold posts you see are the custom attachments anchored onto the titanium screw imbedded into the bone. Also note this bridge runs flush with the gumline to minimize air flow and food collection that can cause issues with speech and cosmetics. Unfortunately it is more challenging to clean when done this way.
3 Unit Hygienic Bridge
One of the ideal cases for bridges is the replacement of a single tooth when the neighboring teeth are good, solid teeth. This case is a perfect example of that and the patient opted for a bridge. When dealing with bottom teeth at the back in situations like this, we have the added option of a different bridge design to aid in bridge maintenance. The hygienic pontic (portion replacing missing tooth) can be shortened to leave a space underneath it to aid in access for cleaning and monitoring the edges of the bridge. As you may suspect, more food will get into this area because of the gap, but the long term benefits of cleansability and maintenance make it very worth while.
3 Unit Hybrid Bridge
When doing bridges it is good to be as conservative as possible. Not all cases require grinding down an entire tooth in order to anchor the bridge and this case is one such example. The tooth behind the space was a pretty solid tooth, but had a good sized filling in it lending it to be a good candidate for a future crown. The tooth in front of the space was a virgin tooth for which it would be a shame to grind it down for a standard bridge. The decision here was to do a standard bridge abutment on the tooth on the left, but only do a metal plate bonded to the inner surface of the tooth on the right (hence the transition line from pontic to tooth on the right). To do this, only minor tooth structure removal was required on the tooth on the right, just enough to help brace the bridge.