CHAPTER 2 Considerations for Managing Partial Tooth Loss
Tooth Replacements From the Patient Perspective
Do we treat or do we manage tooth loss? Is the distinction important as we attempt to help our patients decide which type of prosthesis to choose? For patients who want to know what to expect now and in the future, it is helpful to make this distinction, as it helps them realize that the decision has implications for future needs that may be different between prostheses.
Tooth loss is a permanent condition in that the natural order has been disrupted, and in this sense it is much like a chronic medical condition. Like hypertension and diabetes, two medical conditions that are not reversible and that require medical management to monitor care to ensure appropriate response over time, tooth replacement prostheses must be managed to ensure appropriate response over time.
The term management suggests a focus on meeting needs that may change over time. These needs may be expected or unexpected. Expected outcomes are those that accompany the common clinical course for a type of prosthesis that is related to the tooth-tissue response. This biological toll response is heavily influenced by the type of prosthesis chosen. In addition, various needs due to prosthesis degradation and related to expected time-to-retreatment concerns of life expectancy are seen. Unexpected needs are those that might involve factors related to our control of manipulations (such as tissue damage or abuse, material design flaws, or prosthesis design) or to those out of our control (such as parafunction or accidental trauma).
With this in mind, it is helpful to consider how we approach educating our patients about management of missing teeth. Most often, a typical sequence is used to discuss tooth replacement options with patients: dental implant–supported prostheses, fixed prostheses, and, finally, removable partial dentures. When removable partial dentures are suggested, they are seldom described in the detail in which fixed or implant prostheses are described, as they generally are considered less like teeth and not as desirable a replacement. The desirability of a prosthesis is important to consider, and because removable partial dentures (RPDs) are less like teeth than other replacements, it is important to recognize what this suggests from the patient’s perspective.
Patients’ experiences have involved natural teeth, and their expectations of replacements would best be described within this context. The order with which we provide replacement prosthesis options for consideration is likely developed on the basis of numerous factors, including the following: we may believe we know what’s best for patients, our practice style may not include removable options, we may not have had good experience with removable prostheses and this lessens our confidence in their use, or RPDs do not match our practice resources.
Although these are important factors, the reason to include RPDs in the discussion is related to identifying whether such a prosthesis is viable, and, if so, whether it is the best option for the patient. We discover this only by interacting with our patients regarding their expectations and understanding their capacity to benefit from options of management that have trade-offs unique to each type of prosthesis.
When patients are given information regarding their oral health status, which includes disease and functional deficits, as well as the means to address both, what do they need to hear? To achieve a state of oral health, they need to recognize behavioral issues related to plaque control, so that once active disease is controlled, they have an understanding that best ensures future health. For tooth replacement decisions, complex trade-offs in care choice are often required. The “shared decision making” approach addresses the need to fully inform patients about risks and benefits of care, and ensures that the patient’s values and preferences play a prominent role in the ultimate decision.
It is recognized that patients vary in their desire to participate in such decisions, thus our active inquiry is required to engage them in discussion. This becomes especially important when elective care, which involves potentially high-burden, costly options with highly variable maintenance requirements, is considered.
When patients wish to participate, it is our responsibility to provide them with specific and sufficient information that they can use to decide between treatment options. Specific information ideally comes from our own practice outcomes, in that such information provides effectiveness information and is provider specific. Sufficient information describes exactly what aspects of care are important to the overall decision. Ultimately, it is our role to help patients consider important differences between different prosthesis types.
What then defines important differences? Multiple outcomes combine to describe the overall impact of prosthetic care for all patients. These include technical outcomes, physical outcomes, esthetic outcomes, various maintenance needs, initial and future costs, and even physiologic outcomes that suggest to what extent prostheses “feel” like teeth.
When tooth replacement prostheses are considered from a patient’s perspective, it can be seen that the desire is to replace teeth that serve functional and social roles in everyday life. In considering how well various types of prostheses may meet patients’ specific needs, it is helpful to note what features of the original dentition—the gold standard, in this instance—we strive to duplicate in the replacement. Although it is common to find that existing oral conditions do not easily allow complete restoration to the state of a fully dentate patient, considering the respective strengths and weaknesses of the prosthodontic options (compared with this “gold standard”) helps in identification of realistic expectations.
In this text, the focus will be on a type of replacement prosthesis for patients with some, but not all, missing teeth. The replacement prosthesis ideally should provide function and a level of comfort as equivalent as possible to normal dentition. In achieving this, stability while chewing is a primary focus of attention, and we should strive to determine what is required to ensure it. If the prosthesis will be visible during casual speaking, smiling, and/or laughing, it is obvious that the replacement should look as natural as the surrounding environment. In summary, tooth replacement prostheses should provide a combination of several features of natural teeth: socially acceptable in appearance, comfortable and stable in function, and maintainable throughout their serviceable lifetime at a reasonable cost.
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.
For removable partial dentures that do not have the benefit of natural tooth support at each end of the replacement teeth (extension base removable partial dentures), it is necessary that the residual ridge be used to assist in the functional stability of the prosthesis. When a removable partial denture is selected for a tooth-tissue–supported arch, the prosthesis must be designed to allow functional movement of the base to the extent expected by the residual ridge mucosa. This mucosa movement is variable, but for healthy residual ridge (masticatory) mucosa, movement from 1 to 3 mm can be expected. Consequently, unlike with the tooth-bound space, toot/>