Implant Partials and Overdentures
What is a Dental Implant?
A dental implant is a titanium screw similar to that used by orthopedic surgeons. The fixture is usually allowed to stay under the gum for approximately 4 to 6 months which facilitates bone to implant bonding. The process of bone covering the implant surface, called “osseointegration”, makes the screw solid enough for us to use it for support. The key element of osseointegration is the fact that the fixture must not move within the bone in order to allow for bone to implant bonding. Once the healing process is complete, a permanent porcelain crown can be fitted.
What are Implant Dentures?
Implant-supported dentures (also called overdentures) are another option for patients who are missing multiple teeth. Overdentures are full dentures that are designed to attach to dental implants, so they can be snapped in for a secure fit and pulled out for easy cleaning and care. They are secured by two or more implants and are very different from the traditional dentures your parents or grandparents may have worn (which may have required adhesives to keep them in place).
Why would one consider implant overdentures vs conventional dentures?
The main reason why people complain about their dentures is that the dentures move away from their gums. Since dentures rest on gums that are compressible, such movement of the dentures is expected. Typically, patients get used to these movements in the upper denture and learn to function with them. However, the lower denture is more problematic as it tends to dislodge with tongue movements. Since the lower jaw resorbs 4 times faster than the upper jaw, the lower denture has less bone support than the upper denture. This has led the Prosthodontists to recommend 2 implant overdentures as a standard of care instead of a lower denture. Clips or attachment systems can retain the denture and prevent upward movement, or movement away from the patient’s gum. This leads to improved chewing efficiency, ease of speech, and a sense of security in social situations.
Are all overdentures the same?
There are two different kinds of overdentures. They can be tooth retained overdentures (dentures held by teeth), or implant overdentures (held by implants).
Implant overdentures can be further divided into two subgroups: stud overdentures and bar overdentures. Stud overdentures, also known as ball or locator overdentures, are held by individual implants while bar overdentures are retained attachment clips placed on bars connecting multiple implants.
The main differences between stud and bar overdentures include:
- Stud Overdenture
- Tend to require fewer implants than Bar Overdentures
- Prevent the denture from moving away from the gums
- Bar Overdentures
- The bar provides enhanced stability of the denture
- Prevent the denture from moving away from the gums AND prevent the rocking of the denture
Stud overdentures require a minimum of two implants to support the overdenture. There can be more implants placed to improve the stability of the denture. When two implants are placed, they need to be placed anteriorly (towards the front) of the patient’s jaw. The only function they have is to prevent the denture from moving away from the gums, they are not designed to hold the denture down. Nonetheless, patient comfort is significantly improved with this design.
Bar overdentures have a bar that constitutes the infrastructure of the dentures. The advantage of having a bar is that it not only prevents the denture from moving away from the gum, but it also prevents the rocking of the denture and improves stability, which contributes to enhanced comfort for the patient. Another benefit of the bar overdenture is that, typically, the denture has a superstructure framework that fits exactly over the bar, making the denture stronger. Ultimately, this can help prevent random fractures of the dentures.
The design of an overdenture will depend on the number of implants supporting it. With two implants (usually placed in the positions of the canine teeth), overdentures will likely have the same design as conventional dentures. But when more implants are used and connected with a bar, the denture flanges (extensions) can be reduced and the palate of an upper denture can be removed. The implants provide significantly more stability, comfort, and biting force to the denture. This allows for a better sensation of food on the roof of the mouth and a less cumbersome feel.
Caring for a Dental Crown
Caring for a crown is similar to caring for your other teeth. Once your permanent crown or bridge is cemented, it is important to remember that these porcelain restorations do not decay, but the teeth underneath them do. The most susceptible area for decay is at, or below, the area where the tooth and restoration meet. If this area is not routinely cleaned, bacterial plaque will form around the restoration, which oftentimes leads to decay. This is the most common reason for needing to replace permanent crowns and/or bridges. Therefore, it is important that you maintain a diligent daily home care routine to clean your teeth and gums.
What are the health effects of Implant Dentures?
Most patients who wear dentures are unaware of the fact that they are losing bone and gum tissue. Natural teeth, generally, do an adequate job of stimulating bone tissue, which prevents the bone from resorbing. Once the teeth are gone, there is nothing to prevent the bone tissue from decreasing and dentures have been known to accelerate the resorption process. A solution to this problem is the addition of implants. With implant overdentures, the resorption process is slowed due to the fact that the implants stimulate the bone tissue, to some degree. While implant overdentures are not as effective at stopping bone resorption as implant bridges, they do a significantly better job than dentures alone.
How should implant detnures be maintained?
Denture patients without teeth should maintain their dentures and expect to see a hygienist every 12 months. However, implant dentures will be expected for recare every 6 months, due to the involvement of implants. In those appointments, dentures will be polished and cleaned of any bacteria or fungus. When the surface of the denture is smooth, it becomes unattractive for plaque and bacteria. The same applies to removable appliances that contain acrylic.
In the case of overdentures, there are movable parts and plastic inserts so replacement of inserts may be necessary every 6-12 months. Poorly constructed overdentures may be very expensive to maintain, as some of these mobile parts will wear quicker than they were designed to. It is not difficult to find patients who have had poorly designed overdentures and implant distribution, where the replacement of clips occurs within a couple of weeks of the insertion. Therefore, it becomes very important to see a dentist who can think the design through and make sure the attachments are well distributed in order to optimize the results.
Major Dental Clinics prosthodontists have extensive training and experience in all aspects of dentures and implant dentistry, which allows them to create natural-looking, precision-fit, implant-supported dentures, and partials.
Are there other treatment options I should consider?
While implant overdentures are a great step up from traditional dentures in terms of stability, comfort, and technology, the best denture alternative that modern dental medicine has to offer is an implant bridge. Implant bridges are commonly known as “All-on-4 Dental Implants” or “All-on-4 Immediate Implants”.