The future of complete prosthodontics

The future of complete prosthodontics

REMOVABLE LOUIS PROSTHODONTICS BLATTERFEIN, The future ROBERT M. MORROW, of complete Dayton D. Krajicek, D.D.S.* Veterans Administration Hospit...

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The future



of complete

Dayton D. Krajicek, D.D.S.* Veterans Administration Hospital,



Section editors





rosthodontics is that branch of dentistry which is concerned with the diagnosis, planning, fabrication, and placement of artificial devices to replace one or more teeth and associated tissues. Prosthodontics may be divided into four sections: complete, removable partial, fixed partial, and maxillofacial prostheses. The first three always include the replacement of missing teeth; maxillofacial prosthesis may or may not include this phase of treatment. Dentistry is a profession requiring long, continued academic preparation, special knowledge, and postacademic study. It is a calling, a strong impulse to serve people. Dentistry, like most other professions, seeks to make itself unnecessary. In pursuing this worthy goal, dentistry has embarked upon an intensive campaign of preventing disease. This is not new. Dental literature has always advocated preventive techniques.l More recent years have seen a tremendous emphasis on prevention. TOOTH


In the main, tooth “mortality” arises from two almost universal diseases, dental caries and periodontal disease. Dental caries begins early in life. If left untreated, the patients become candidates for prostheses. Periodontal disease also begins early in life.2 With time and neglect, the disease progresses and loss of teeth follows. The prevention of dental caries represents dentistry’s most successful public health effort. Fluoride therapy, dietary restrictions, food supplements, and pit and fissure sealants have greatly reduced the caries attack rate. It is impossible to calculate the number of people who are benefiting from the fruits of caries prevention. The etiology of periodontal disease is baffling; factual information is meager.’ Since prevention depends, in a large measure, on home care, efforts to inspire this type of prevention on a mass scale have been unsuccessful.” Professional therapy awaits more precise information on the nature of periodontal disease.” As more Read




the American



Las Vegas,


VoIume Number


37 ‘2


I. Edentulous









No. of edentulow persons

Per cent

1957-58 1971 1975

173,619,OOO 202,360,OOO 211.925.000

21,900,OOO 22,600,OOo 24,200,OOO

12.6 11.2 11.4

teeth are spared from dental caries, we may anticipate that they will become victims of periodontal disease. Prevent+ of tooth-destroying diseases would decimate prosthodontics if not relegate it to history. This would be in keeping with our professional destiny; such fancy is not immediately impending. There is little prospect that the number of patients requiring prosthodontic therapy will decline in the near future. Prevention of periodontal disease must advance to the stage of caries prevention before the need for prosthodontics declines. SOURCES


The judgments made in this report were based on three sources of information. The Bureau of the Census, the National Center for Health Statistics of the Department of Health, Education and Welfare, and the Bureau of Economic Research and Statistics of the American Dental Association. Data were not always available for matching years. In some instances, averages provided acceptable information. In others, percentages derived from existing data provided acceptable projections, making possible the coordination of total populations, numbers of edentulous persons, numbers of people with dental prostheses, and numbers of active dentists for the appropriate years. PROJECTIONS The Bureau of the Census issues four projections of future populations based on several assumptions. The data used in this report are from the third projection was 72 (Series E) , next to the lowest projection. 4 In 1974, man’s life expectancy years5 Immigrants in 1974 numbered 360,000 persons, and this number is not expected to decline. 5 The 1974 fertility rate of 1.86 is the lowest in history.5 Nevertheless, the population of the United States is expected to rise at a rate of about 2,500,OOO persons per year up to 1985. For the year 2000, the estimated population is 264,430,OOO (Series E). If present conditions continue, the United States is expected to reach a population of 277,000,OOO and zero growth during the 21st century.6 The American Dental Association has also projected the number of active dentists up to the year 1985.1 Information on the projected numbers of edentulous persons for future years was unavailable from any source. The percentage of edentulous persons ranged from 12.6 in 1957-58 to 11.2 in 1971 to 11.4 for 1975.7, 8 The mean for these 18 years was 11.7 per cent (Table I). This report arbitrarily placed future


.I. Prosthet. Februaly.


Table II. Denture




Dent. 1977


No.of edentulous persons


Complete denture Removable partial denture Fixed partial denture Complete fixed partial denture Complete removable partial denture Fixed removable partial denture Denture-wearing population Edentulous population

Table III. Edentulous


Per cent

23,000,OOO 13,000,000 4,000,000 400,000


2,500,000 600,000 44,000,ooo 24,200,OOO

I.2 0.3 20.8 11.4,

6.3 2 0.2

persons and replacements


No. of edentulow persons

1958 1971 1975 19txo* l985* 1990* 2000;

21,900,OOo 22,600,000 24,200,oOO 24,656,OOO 25,827,OOO 27,130,OOO 28.100.000

Replacement 3,056,ooo 3,164,oOo 3,388,OOO 3,452,OOO 3,716,OOO 3,798,OOO 3.934.000

at 11 per cent.

projections at 11 per cent, which represents a reasonable and conservative estimate. Reduction in percentage does not imply a reduction in numbers since projections on population growth indicate continued increases until some time in the 21st century. Therefore, the judgments presented in this report are based, in part, on existing data and projections presented by reliable agencies. The number of edentulous persons is projected on the basis of past experience of the author.

EDENTULOUS PERSONS Denture wearers include those people with fixed partial, removable partial, or complete dentures and with combinations of all three. In 1975, they numbered 44,000,OOO persons or 20.8 per cent of the population (Table II) .* This report will concentrate only on the number of edentulous persons and complete denture wearers. Past trends in the edentulous population in the United States suggest an increased need for complete dentures. The 1957-58 survey estimated the number of edentulous persons at 21,900,OOO or 12.6 per cent of the population. In 1971, the edentulous population was estimated at 22600,000 or 11.2 per cent of the populations Both the percentage and number increased in the 4 year period of 1971 to 1975 (Table I). Of the 24,200,OOO edentulous persons estimated in 1975, 1,200,OOO were without dentures.8 In 1971, l,lOO,OOO persons had no dentures. In addition, 1,700,OOO persons (8 per cent) did not use their dentures and 6,500,OOO(30 per cent) indicated a need

22T:r“2’ Table


IV. Population

and patient/dentist


of complete



ratio No. of



practicing dentists

1958 1971 1975 1980* 1985;

173,619,OOO 202,360,OOO 211,925,OOO 224,138,OOO 235,701,OOO

88,000 100,500 121,150 122,000 138,650

Patient/ dentist ratio 1,848 2,013 1,927 1,726 1,624


for new dentures.7 The three categories-those use their dentures, and those who indicated per cent of the edentulous population, or prosthodontic therapy. These figures compare complete dentures for 239 patients who had dentures at no cost. Of these patients, 29.7 poor quality and 7.7 per cent of the patients to masticate efficiently.g DENTURE

with no dentures, those who do not a need for new dentures-represent 39 9,400,OOO persons, needing complete favorably with a critical evaluation of the opportunity to replace ineffective per cent had dentures judged to be of with good-quality dentures were unable


The useful, effective life span of complete dentures has not been established. There have been suggestions that complete dentures should be relined or remade at 5 or 6 year intervals. “3 I1 In the 1975 data, the 40 to 49 year age group presented 2,200,OOO complete denture wearers. In the 50 to 59 year age group, there were 4,400,000, and at 60 years and over, there were 11,900,000.8 Based on the life expectancy of 72 years and these data, it is projected that 3,500,OOO denture patients in addition to those who become edentulous will require denture relines or new dentures each year (Table III). The number of persons requiring replacement dentures increases the potential number of denture patients by 14 per cent. These data strongly suggest the need for a systematic recall system for complete denture patients. PROJECTED



The increase in population and the vast number of persons not receiving dental treatment stimulated the effort to increase the number of practicing dentists. For the next 10 years, the number of practicing dentists will increase more rapidly than the population. Since 1956, the number of practicing dentists has been based on those younger than 68 years of age. An additional 3,500 have been placed in the category of related professions, such as administrators, teachers, and investigators, or in dental industry.4 The continued increase in the number of practicing dentists will reduce the patient/dentist ratio. Table IV lists the population, number of active dentists, and patient/dentist ratio for the United States.4 The ratio reached a peak in 1971 and then declined as the number of dentists increased.4 The projected decrease in patient/dentist ratio after 1975 is approximately 1.6 per cent per year. These promising projections augur professional dental care for more persons.

J. Prosthet. February,




V. Estimated





No. of dentists

1958 1971 1975 1980 1985

88,000 100,500 121,150 122,000 138,650

Dent. 1977

ratio Potential denture

complete patients 249 259 218 197 182

It is more difficult to project the ratio of dentists to edentulous persons. The projected number of dentists includes specialists such as oral surgeons, orthodontists, periodontists, and pedodontists who do not practice complete prosthodontics. From 1958 to 1985, the number of dentists will increase by 57 per cent or 2.1 per cent per year for the 27 years. The number of denture wearers during this period will increase by 18 per cent or 0.7 per cent per year. The result will be a reduction in potential complete denture patients, resulting in a reduction in denture patient: dentist ratio of about 2.5 per cent per year (Table V) . GEOGRAPHIC


The geographic distribution and growth trends portend further imbalance of the patient/dentist ratio. In 1974, over two thirds of the population lived in metropolitan areas. However, the largest metropolitan areas have shown the least growth since 1970.5 The central cities of metropolitan areas have actually lost population since 1970. There has been a corresponding increase in population in rural areas. The population of the United States is concentrated in the Middle Atlantic, East North Central, and South Atlantic regions. These areas constitute 17 per cent of the land mass of the United States and contain 53 per cent of the population, including 54 per cent of complete denture wearers and 53 per cent of the active dentists. However, the population is not static. The population in the southwestern states is increasing more rapidly than that in the northeastern states.4T ’ The economic basis of families combined with the size of households is also a factor in contemplating the future of prosthodontics. Families averaging 2.8 persons with a yearly income of less than $15,000 represent 47 per cent of the population. They also constitute 85 per cent of the complete denture wearers. The per-capita income of persons living in areas of the greatest concentration of population and the highest percentage of complete denture wearers is 11.4 per cent higher than that of the remainder of the stateside population. Since the population is shifting toward the southwestern states and away from the northeastern states, the complete denture patient/dentist ratio should increase and decrease in these areas in similar fashion. DENTURIST


A 1976 survey by the Oregon Dental Association presents the opinions of dentists in a state close to the Canadian border where denturism is practiced. The questionnaire was answered by less than half of the dentists in the state, of whom 2 per cent were prosthodontists and 83 per cent general dentists. One must assume that the general dentists practiced complete denture therapy.




of complete



The practice of dentistry by nondentists did not alarm the dentists, although the patient/dentist ratio in Oregon is 23 per cent below the national average. While the dentists thought their practices had not suffered and would not suffer, they considered denturism a threat to oral health. Almost half of the respondents (49 per cent) reported that the number of patients receiving removable prosthodontic therapy was decreasing. No explanation for the decrease was sought in the survey. The decrease in the number of patients requiring removable prostheses is in keeping with the trend suggested by the projected data on the general population, population of dentists, and number of edentulous persons. It is obvious that as the patient/dentist ratio decreases, the need for nonprofessional personnel to engage in dental practice should also decrease.

DISCUSSION AND CONCLUSIONS The dental profession cannot find joy in the prospect of continuing mortality of teeth. Nevertheless, the exigencies of health care demand prostheses to maintain good health and happiness. Prosthodontics has provided successful function and emotional well-being to millions of people. Projections of population, numbers of dentists, and edentulous persons must be taken with circumspection. Untoward and unforseen factors may alter the anticipated relationships. Nevertheless, projections indicate a trend. It is in this sense that the conclusions are drawn. The projections reported in this article counsel continued prosthodontic therapy. Until the rate of tooth mortality radically declines, the need to maintain and even promote a superior service manifests professional integrity. With 38 per cent of the complete denture-wearing public expressing dissatisfaction, the answer lies in research to improve both the useful life span and the function of dentures. This can come only from those persons who have undertaken the continued academic preparation, have special knowledge, and have the professional outlook of dentists. In addition, practicing dentists have the training and ability to understand and interpret contributions to research. To relegate the professional obligations to less trained and less competent dental ltboratory technicians holds promise of reducing the quality of oral health care for edentulous patients and increasing the percentage of dissatisfied patients. The shift in population from large metropolitan to rural areas and from the Northeast to the Southwest may cause further disruption in local areas and in patient/dentist ratios. Patients, especially retirees, face few problems in moving. Dentists face many. The individual state Board requirements confine dentists to states where they are licensed. There will be a need for reciprocity to maintain a healthy patient/dentist ratio. Prosthodontics has a promising future. This highly successful therapy will continue to serve the public with functional substitutes for missing dental organs. With continued research, prosthodontics will improve its service and look to the future with pride.

I thank M. Cristol of the Bureau of Economic providing information used in this report.




of the




J. Prosthet. February.


Dent. 1977

References 1. Hunter, J.: The Natural History of the Human Teeth, London, 1778, Printed for J. Johnson, p. 124. 2. Taichman, N. S.: Some Perspectives on the Pathogenesis of Periodontal Disease, J. Periodontol. 45: 361-363, 1974. 3. Greene, J. C.: The Ease for Preventive Periodontics, J. Dent. Child. 42: 24-27, 1975. 4. Bureau of Economic Research and Statistics, ADA: Growth in Population and Number of Dentists to 1985, J. Am. Dent. Assoc. 87: 901-903, 1973. 5. World Almanac, New York, 1976, Newspaper Enterprise Association, Inc. 6. Statistical Abstracts of the United States, United States Department of Commerce, Social and Economic Statistics Administration, Bureau of the Census, Washington, D. C., 1974. 7. Edentulous Persons Publication M. (HRA) 74-1516, United States Department of Health, Education and Welfare, National Center for Health Statistics, Rockville, Md., 1974. 8. Bureau of Economic Research and Statistics, ADA: Survey of Denture Wearers, 1976. 9. Yoshizumi, D. T.: An Evaluation of Factors Pertinent to the Success of Complete Denture Service, J. PROSTHET. DENT. 14: 866-878, 1964. 10. Craddock, F. W.: Prosthetic Dentistry, ed. 3, London, 1956, Henry Kimpton, p. 411. Il. Schlosser, R. 0.: Complete Denture Prosthesis, Philadelphia, 1940, W. B. Saunders Company, p. 290. VETERANS






IADR A new

RTV silphenylene

PROSTHODONTIC maxillofacial

D. H.

Lewis, D. R. Cowsar, Institute, Birmingham, Ala.

A. C. Tanquary,





R. Tarwater.




An improved elastomer with an optimum balance of mechanical properties, processability, environmental stability, colorability, and esthetics, for use in fabricating extraoral maxillofacial prostheses, was sought. An arylene silicone polymer, polytetramethylsilphenylenesiloxanedimethylsiloxane, was synthesized and formulated as a pourable, viscous, room-temperature-vulcanizing liquid. Silphenylene polymers are colorless and will accept either intrinsic or extrinsic coloration. When mixed with conventional catalysts, the silphenylene vulcanizates can be easily and reliably cast in closed dental stone molds to give prostheses that are strong and tough yet soft and pliable. Typical values for tensile strength, elongation at break, modulus at 100% elongation, and hardness are, respectively, 1400 psi, 1000 psi, 50 psi, and 35 (Shore A). Since the arylene linkages in the silphenylene polymers impart unusually high values of surface energy to these silicone elastomers, they have an excellent tactual as well as visual resemblance to skin, and they adhere well to tapes and adhesives. A preclinical toxicologic evaluation has been completed, and the materials are currently undergoing clinical evaluation. This


was supported

Reprinted from the editor, and the American

Journal Dental


of Dental Association

Contract Research (copyright

No. NOI-DE-42435. with permission holder).

of the