During a typical work week, I tend to discuss tooth replacement options more than any other procedures with patients. There are a wide variety of events that may have caused a patient to lose their teeth: decay, neglect, trauma, erosion, etc. Whatever the case maybe, there is a solution.
To understand tooth replacement options one has to understand the physical changes that take place once a tooth is lost. When a tooth is extracted, the bone that was supporting the tooth begins to shrink. The bone around the socket has a loss of 40% – 60% of bone width within the first two years of an extraction. In some areas research shows a loss of an average of 4 mm of vertical bone within the first year of an extraction, and will continue to shrink indefinitely.
In discussing options, let’s consider the replacement of one tooth that has been lost. Keep the previously mentioned bone loss statistics in mind as we discuss the potential tooth replacement options.
A partial denture is a removable appliance that is used to replace a single missing tooth or multiple missing teeth. Traditionally this appliance is made with a metal frame with an acrylic pink base (representing gum tissue) and a white acrylic denture tooth used in the area of the missing tooth. One may also use a nylon based “flex” partial as an alternative. Both partials have their pros and cons.
To have a properly fitting partial you have to slightly reshape the adjacent teeth to keep the partial steady. When designing the partial, all other teeth need to be stable and decay free with adequate bone support. If the partial is designed and fabricated based on the existing number of teeth and restorations, any change can cause it to be unstable. If an additional tooth is lost or a restoration is lost or changed, then the partial is no longer as stable as its original design. Sometimes you can add the newly missing tooth to an existing partial, but it is still not what it was originally designed for.
The partial does not solve the problem of bone loss. In fact, the continued pressure of the partial on the site of the extraction will cause the bone loss at a quicker rate. The partial also puts pressure on other teeth causing mobility. The spaces between the teeth and the partial become food traps that can lead to more decay and ill-fitting partial denture.
Traditional dentistry incorporates the use of a fixed partial denture (a bridge). This is a metal and/or porcelain appliance fabricated in a dental lab that is permanently cemented on the adjacent teeth of the missing tooth space. To fabricate the bridge we would reduce the teeth on each side of the space by 1-2 mm on all surfaces, take an impression, fabricate and cement a temporary bridge, and once fabricated cement the final restoration.
The down side to using a bridge is the fact that we have to cut the adjacent teeth. If the teeth already have an existing restoration it is not as tragic. But, if the tooth has no existing restoration, then we are cutting a perfectly good tooth. Once tooth structure is gone, you can add it back. The next problem is the life expectancy of a bridge is approx. 7-8 yrs. If there is a problem with one of the supporting teeth, then you can lose the bridge, and in the process lose all three teeth.
The other problem is the previously mentioned bone loss. The bridge doesn’t stop the bone loss. This causes the supporting bone around the adjacent teeth to reduce. The bone loss leads to the recession of the gum tissue around the margins of the restoration, as well as under the area of the missing tooth. This space becomes a food trap and can speed up the demise of the restoration as well as not being esthetically pleasing to the patient.
A dental implant is a titanium cylinder placed in bone at the site of the missing tooth. Once the implant is placed, time is given for the bone to grow around the implant to become stable. Once the implant becomes stable, then a healing abutment is placed over the top allowing the gum tissue to heal in a specific shape. An impression is taken of the dental implant and sent to the dental lab to fabricate a crown. The crown is then cemented over of the implant replacing the missing tooth.
The dental implant represents the missing root of the tooth, and gives support to surrounding bone. This support gives bone reason to be there, and is retained for a longer period of time. Research indicates longevity of the dental implant is significantly greater than other tooth replacement options. In the process of placing the implant, no other teeth are touched. You are only concerned for the tooth that is missing. This allows for longevity of the surrounding teeth as well.
The cost of a dental implant is probably one of the first factors patients look at. But when comparing the implant to other restorations, it is not always as cut-and-dry as it seems. When the costs of a partial denture vs. a dental implant, or a dental implant vs. a bridge are compared, dental implants are usually the most expensive option upfront. When future costs are calculated, however, the dental implant may be the most cost-effective solution. While a dental implant requires little maintenance and can last a lifetime, a bridge or denture usually requires multiple refittings and replacement in the course of a lifetime.