Removable Partial Dentures (RPDs) are used when there are still natural teeth left. The missing teeth are replaced by this type of denture in an effective and esthetic design that uses both the soft tissue ridge and teeth to hold it securely in place. This tooth replacement is removable by the patient, which makes cleaning easier. The new teeth will look natural and are made from plastic or porcelain (ceramic) materials. The foundation of the partial denture can be plastic or a combination of plastic and metal. Because removable partial dentures use teeth and soft tissue for support, you may be given the opportunity to choose a variety of treatment plans. Your dentist will discuss these options after a thorough examination of your teeth, soft tissue (gums and cheeks), and remaining bone and surrounding anatomy. The examination should also include x-rays (radiographs) or impressions to make models of your mouth. After reviewing all the necessary information with your dentist you will have a better understanding of the benefits of and RPD and other options available to you.
The procedure is relatively simple for the patient. Your dentist will slightly modify selected anchor teeth (this can usually be done without any local anesthesia) and then take a series of impressions. There will, however be several follow-up appointments. Usually there will be a metal framework try-in and a wax try-in (teeth set in wax on top of the metal framework). Once the patient is satisfied with the esthetics and function, the RPD is sent back to the laboratory for final processing. This will turn the wax stage into the final RPD, where the wax is replaced with the more durable pink acrylic.
There are different types of RPDs that we need to distinguish. They all have their own application and are designed to replace missing teeth either permanently or just on an interim basis until another more permanent prosthesis is used to replace them.
Interim RPD (Treatment RPD, Flipper)
This type of partial denture is usually entirely fabricated from acrylic and offers thus only very marginal stability (see image below). It's advantage is that it can be quickly manufactured, quickly repaired and it is relatively inexpensive. The Flipper is usually only used as a means to temporarily replace missing teeth until a more permanent restoration replaces it. Flippers are frequently used in Implant Dentistry as an interim solution, because Dental Implants can sometimes take a long time to integrate into the bone, before they can be loaded with teeth.
These are the Partial Dentures that are normally worn for long term purposes. The RPDs feature a metal base (usually a chrome-cobalt or vitallium alloy), which acts as a stable platform onto which the pink acrylic and the teeth are processed. Another identifying feature are the metal clasps which attach to some of the remaining anchor teeth in the mouth. These clasps are responsible for the RPDs retention. Cast Metal RPDs usually don't rest on gum tissues (at least not to the point were they transmit chewing forces to the tissues), rather, they are designed to transmit the chewing forces down the long axes of the individual anchoring teeth, to which the clasps attach.
Development of new and advanced types of plastic led to this type of RPD. In this RPD the metal parts are replaced with an advanced plastic material that offers flexibility and strength. The most common brand name is ValPlast® (see image below). Its flexibility make it nearly unbreakable and it can also be kept quite thin. The downside of this type of partial denture is that it rests on gum tissue rather than teeth, because the clasps are designed to brace the anchor teeth at their necks, rather than their crowns (this material is too flexible for direct tooth clasps). This can sometimes cause sore spots, especially with new RPDs.
