Chapter 1
Partial Denture Provision
Aim
In industrialised countries, as the proportion of adults retaining some of their teeth into old age increases, so will the likely need for prosthetic intervention. This chapter aims to provide an overview of the need and demand for partial dentures to restore partially dentate adults.
Outcome
After reading this chapter the practitioner should be aware of the effectiveness and consequences of partial denture use.
The Partially Dentate Population
Evidence from various national dental health surveys in developed countries clearly indicates that the proportion of people with no teeth at all will continue to decline and that more people will retain some of their own teeth into old age. The results of the 1998 national dental health survey in the UK indicate that 87% of all adults had some natural teeth but that this proportion was strongly influenced by age. The mean number of missing teeth by age group for a number of developed countries is shown in Fig 1-1 using data from the WHO Collaborating Centre, Sweden (2003). Common trends are that significant tooth loss only becomes apparent after 45 years of age and that the number of missing teeth increases with age. The percentage of people =45 years of age provided with partial dentures differs between countries, a variation that reflects both differing public and professional attitudes to partial denture use and healthcare systems, but can reach levels of 20-30%. Where provision of partial dentures is a commonly used treatment option for the partially dentate, the principal deciding factor as to whether or not a partial denture is used appears to be the number of remaining natural teeth. Results of the 1998 UK Dental Health Survey clearly indicate that there is a cut-off point at 21-24 teeth and people with 21 or more teeth are unlikely to have removable partial dentures (Fig 1-2). This supports the important concept of a "functional dentition" which allows the patient sufficient function and comfort without the need for tooth replacements.
Fig 1-1 The mean number of missing teeth by age group (data from WHO Collaborating Centre, Malmö, Sweden 2003).
Fig 1-2 The proportion of partially dentate adults with removable partial dentures by number of natural teeth (Adult Dental Health Survey, Oral Health in the United Kingdom 1998).
The number of teeth that people retain has also increased. In the UK in 1998, over 72% of adults had 21 or more teeth although this figure reduced with age such that only 10% of people aged =75 years had 21 or more teeth. Projections for 2018 suggest that 90% of 16-74 year olds in the UK will have a natural dentition of 21 or more teeth though this proportion will again reduce with age. Such projections need to be seen in the context of increasing life span in industrialised countries with an increasing percentage of populations =65 years old. In the UK, for example, the number of adults over the age of 65 years is expected to rise by 2.7 million by 2021.
Increased tooth retention reflects the development of more positive attitudes to dental health and improved access to dental care. Adults increasingly wish to retain their natural teeth and are prepared to accept treatment recommended by their dentists to save their teeth. There is good evidence that dental attendance improves the possibility of retaining at least some teeth over the course of a lifetime. Increasingly, adults find the prospect of complete dentures unacceptable though, interestingly, such attitudes do not seem to apply to the use of partial dentures. The future then is one of increasing numbers of older partially dentate adults who may require partial dentures to replace missing teeth.
Projections based on data from national surveys have been used to estimate the future treatment need for the partially dentate. These estimates point to an increased need for both fixed and removable prosthesis. In the USA the projected total need for fixed and removable prosthesis is put at 115% of current provision by the year 2020. Partial dentures are the simplest, cheapest and by far the most common method of replacing missing teeth. In the UK approximately 30% of all middle aged and elderly adults have been provided with partial dentures. There is, however, an increasing acceptance of the use of fixed prosthesis by elderly patients and a growing recognition that implant-supported prosthesis offer a viable and, perhaps, more effective long-term treatment alternative for the partially dentate. Socio-economic factors would suggest, however, that the more frequent use of partial dentures will remain the situation for the foreseeable future. This together with the evident population trends would suggest that the need for partial dentures in developed countries is unlikely to decrease in the future and will probably remain relatively stable.
The Effectiveness of Partial Denture Provision
For the very large majority of cases, partial dentures are provided to improve appearance by restoring visible spaces resulting from the loss of typically anterior teeth and to improve function by restoring missing posterior, usually molar, teeth. In addition, the use of partial dentures is often advocated to maintain occlusal stability. This section will review the effectiveness of partial denture use in these circumstances.
Appearance
The improved appearance gained by the replacement of missing anterior teeth really needs no amplification (Fig 1-3). It is probably the main reason patients request partial dentures and, perhaps, continue to wear them but this is not inevitably the case. There is good evidence to suggest that the dentist's and patient's view of what is or is not a satisfactory appearance can differ markedly (Fig 1-4). The key factor is, of course, the patient's opinion and this is strongly linked to what they perceive is an acceptable appearance in their social environment, a concept of social ease and acceptability well described by social scientists as "passing". The age of the patient does seem to influence the importance attached to appearance. For younger patients, the loss of visible teeth is likely to be unacceptable and a powerful driving force to seek treatment, yet many elderly patients can find the presence of visible spaces resulting, for example, from the loss of first premolar teeth quite acceptable (Fig 1-5). As age increases there appears to be a greater focus on the need for acceptable function rather than appearance.
Fig 1-3 The presence of visible spaces because of missing anterior teeth is likely to be the main factor motivating this patient to seek treatment to replace them.
Fig 1-4 Somewhat surprisingly, the patient was insistent that the missing UL2 should not be replaced.
Fig 1-5 Many elderly patients find the presence of visible spaces quite acceptable.
Masticatory function
The classic description of the possible effects of a reducing number of natural teeth on masticatory function is shown in Fig 1-6. Tooth loss, in particular that of posterior teeth, results in difficulty chewing and biting food - that is a limitation of masticatory function. This in turn leads to changes in food choices, an impaired dietary intake that may be associated with nutritional deficiency. Replacement of missing teeth restores masticatory function and allows the patient more dietary freedom and the possibility to improve dietary intake.
Fig 1-6 The possible effects of a reducing number of natural teeth on masticatory function.
It was for many years a basic assumption that the progressive loss of posterior teeth would reduce chewing efficiency to the extent that problems of digestion would ensue. Indeed, there is evidence to suggest that as teeth are lost so objective measures of masticatory performance deteriorate. However, many patients with large numbers of missing posterior teeth have little or no complaint about their ability to chew food. They have no perceived functional limitation and, indeed, the poor correlation between objective and subjective assessments of masticatory function is a common research finding. Recent research suggests that patients can masticate adequately without molars and even second premolars, the assumption being that they compensate for a poor occlusion by swallowing larger particles of food rather than chewing for longer. The factor determining whether a patient perceives a limitation of masticatory function appears to be the number of pairs of occluding posterior teeth. Evidence suggests that unless the patient has fewer than three occluding pairs of posterior teeth there is no socio-functional benefit to be gained from replacing missing molar teeth in shortened dental arches. Assuming no loss of anterior teeth, this equates to a "functional threshold" of 21 or more teeth with three to five pairs of occluding posterior teeth - the "functional dentition" referred to earlier in the chapter.
The relationship between limitation of masticatory function resulting from tooth loss and impaired dietary intake has been established but much less clearly for the partially dentate than it has been for the edentulous. The indications are that the number and distribution of teeth are strongly associated with dietary intake. For example, the probability of achieving the recommended daily intake of a number of fruit and vegetables and that the measured intake of dietary fibre and vitamin C appears to fall with reducing numbers of pairs of occluding posterior teeth.
Although an improved...
