CHAPTER 2 Considerations for Managing Partial Tooth Loss
Tooth Replacements From the Patient Perspective
Tooth-Supported Prostheses
For partially edentulous patients, available prosthetic options include natural tooth–supported fixed partial dentures, removable partial dentures, and implant-supported fixed partial dentures. How well these options restore and maintain the features of natural teeth mentioned previously depends to a large extent on the numbers and locations of the missing teeth. The major categories of partial tooth loss (see Chapter 3) are those (1) with teeth both anterior and posterior to the space (a tooth-supported space), and (2) with teeth either anterior or posterior to the space (a tooth- and tissue-supported space). All prosthetic options listed are available for the tooth-bound space (although they are not necessarily indicated for every clinical situation), but only removable partial dentures and implant-supported prostheses are available for the distal extension (recognizing limited application of cantilevers).
Removable partial dentures can be designed in various ways to allow use of abutment teeth and supporting tissue for stability, support, and retention of the prosthesis. In terms of tooth-bound spaces, the removable partial denture is like a fixed partial denture because natural teeth alone provide direct resistance to functional forces. Because natural teeth support the prosthesis, it should not move under these functional forces. In this condition, the interface between, or relationship of, the removable partial denture framework and the abutment teeth should be designed to take advantage of tooth support—similar to the relationship between a fixed partial denture retainer and a prepared tooth. This means that it should provide positive vertical support (rest preparations) and a restrictive angle of dislodgment (opposing guide planes). Put another way, when the removable partial denture is selected for a tooth-bound situation, stability under functional load should be as well controlled as a fixed partial denture when appropriate tooth preparation is provided. Because removable partial denture clasps do not completely encircle the tooth, as a fixed partial denture retainer does, they must be designed to engage more than half the circumference to allow the prosthesis to maintain position under the influence of horizontal chewing loads. It should be obvious that careful planning and execution of the necessary natural tooth contour modifications are required to ensure movement control and functional stability for removable partial dentures supported by teeth. Similarities between the prosthesis-tooth interface for fixed partial dentures and for removable partial dentures are highlighted to emphasize the modification principles required to ensure stability for movement control in removable partial dentures. Over time, natural tooth support can be maintained as with the fixed partial denture. Chapter 14 helps to explain how this is accomplished when natural tooth modifications or surveyed crowns are produced.