Constructions of partial dentures

Partial defect of dentition is the lack from 1 to 13 teeth.

• It is divided into:• Small defects (1-3 teeth)• Medium (4-9 teeth)• Large (10-13 teeth)

Kennedy classification

• A removable partial denture or bridge usually consists of replacement teeth attached to a pink or gum-colored plastic base, which is connected by metal framework that holds the denture in place in the mouth. Partial dentures are used when one or more natural teeth remain in the upper or lower jaw. A fixed (permanent) bridge replaces one or more teeth by placing crowns on the teeth on either side of the space and attaching artificial teeth to them. This "bridge" is then cemented into place. Not only does a partial denture fill in the spaces created by missing teeth, it prevents other teeth from changing position. A precision partial denture is removable and has internal attachments rather than clasps that attach to the adjacent crowns. This is a more natural-looking appliance.

The flexible framework RPD's

• The most recent advance in dental materials has been the application of nylon-like materials to the fabrication of dental appliances. Nylon generally replaces the metal, and the pink acrylic denture material used to build the framework for standard removable partial dentures. Nylon is similar to the material used to build those fluorescent orange traffic cones you sometimes see on highways. It is nearly unbreakable, is colored pink like the gums, can be built quite thin, and can form not only the denture base, but the clasps as well.

• Even though this type of denture does not rest on the natural teeth like the metal framework variety, the clasps rest on the gums surrounding the natural teeth. This tissue, unlike the gums over extraction sites, is stable and changes very little over time which keeps these RPD's stable and unchanging similar to the cast metal variety. The clasps can be seen (if you look hard) on the image on the right below just under my thumb and index fingers. This type of partial denture is extremely stable and retentive, and the elasticity of the flexible plastic clasps keeps them that way indefinitely.

A lower Nylon based partial denture

The Vitallium/Nylon Partial denture

• A good alternative to the all-nylon partial denture is one made with a combination cast metal framework with nylon clasps. This has the advantage of being tooth supported (like the cast metal framework partial denture discussed above) and also having gum colored plastic clasps like the nylon partial.

• This combination of metal framework and plastic clasp eliminates most of the difficulty of recurrent sore spots, since the framework resists movement and pressure from the clasps, while having the benefit of nearly invisible clasps.

The Nesbit RPD

• The flexible framework RPD can replace any number of teeth in a dental arch, similar to the flipper and cast metal RPD. There is, however, one type of removable tooth replacement device that can (legally) be built ONLY out of the flexible framework variety of material. This is the single tooth RPD that we refer to as a NESBIT.

• Dentists used to build Nesbits for their patients all the time. They were composed of a single denture tooth (usually a back tooth) between two cast metal clasps which attached onto the teeth on either side of the missing one. They looked a little like spiders when out of the mouth. Patients tended to like them, but they came to an abrupt end in the 1970's. Prior to that time, in the rare event that a patient swallowed his appliance, he either waited for it to pass, or sought medical help on his own assuming that the accident was his own fault. In rare instances, the metal clasps were sharp enough to cause damage to the digestive system. After that time, tort lawyers discovered that it was a law suit made in Heaven, (or Hell depending on your point of view) and it didn't take the dental profession long to abandon this service.

• The design of the new flexible plastic framework takes the danger out of an accidental swallowing of the appliance. In the event that someone did swallow one, it is unlikely that any damage could be done to the lining of the digestive system. This is a series of pictures that show the form and function of a nylon Nesbit.

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