Herschel S. Horowitz

Occlusal relations in children in an optimally fluoridated community. IV. Clinical and social-psychological findings.

Abstract No Abstract Available. From the Division of Dental Health, National Institutes of Health, Public Health Service.

Ethical Considerations in Human Experimentation

During the past several years, there has been increasing interest in and concern for the ethical and moral considerations that pertain to the conduct of biomedical research in human beings. At the present time, before approving a research project, virtually all private or governmental agencies in the United States that support clinical research require written assurances from prospective investigators or institutions, that the rights and welfare of participating human subjects will be protected during all phases of the study. Research institutions have thus established committees to review proposed research in human subjects at their institutions, or utilize ad hoc committees for this purpose. Review committees must be competent to review a proposed study scientifically and to determine the acceptability of the study in terms of local law, standards of professional conduct and community practice. These committees should include a variety of professional and scientific personnel from the institution, as well as representatives from the community, such as lawyers, clergymen, or members of consumer-interest groups who may add other dimensions to the opinion of the scientific or professional members. BASIC PRINCIPLES OF ETHICS IN RESEARCH INVOLVING HUMAN SUBJECTS.-Any research that involves human subjects must be based upon scientific principles that provide a sound rationale for the research. The justification for the research should be based upon findings obtained from laboratory or animal experiments, findings from other clinical studies, or scientifically established facts. Research involving human subjects should be conducted by or be under the supervision of clinical investigators who are scientifically qualified and experienced. All study personnel should be skilled and exercise great care in carrying out the studys procedures. The principal clinical investiga-

Evaluation of Self-Administered Prophylaxis and Supervised Toothbrushing with Acidulated Phosphate Fluoride

In Sao Paulo, Brazil, 566 children, 14–17 years old, completed a 3-year study to evaluate the anticaries effect of self-applications of acidulated phosphate fluoride (APF). There were five study group

Evaluation of a Combination of Self-Administered Fluoride Procedures for Control of Dental Caries in a Non-Fluoride Area: Findings after 2 Years

In 1972, a self-administered fluoride program was initiated in Nelson County, Va., a fluoride-deficient area. Children in elementary school (grades 1–6) ingest daily an acidulated phosphate-fluoride tablet (1 mg F), rinse weekly with a 0.2% NaF solution and are provided with an F dentifrice for use at home. Baseline dental exams (DMFS) were made of 2,135 children in grades 1–12. In 1974, follow-up exams were made in grades 1–8 (ages 6–13). Baseline findings for children aged 6–13 in 1972 showed a mean prevalence of 5.42 DMFS. The corresponding score for their cohorts in 1974 was 4.60 DMFS, a difference of 15.1%. The data were also analyzed using estimates of 2-years caries increments at the baseline and from 1972 to 1974. For all 2-year age spans (6–8 through 11–13), the estimated mean increment was 33.5% lower after 2 years of the program than prior to its initiation.

Comparability of Study Groups in Clinical Trials of Caries Preventive Agents

When initiating clinical trials of dental caries preventive agents, it is essential that treated groups and controls have a similar potential for developing decay. Some investigators use randomization as a method of initially equating groups on unknown factors that affect incremental decay. Other investigators attempt to improve strict randomization by preceding it with various methods of stratification. They assume that certain factors, such as dental age (number of erupted teeth) and past caries experience, affect a childs potential for developing decay. Data from control groups of ongoing or completed studies can help determine whether various stratification procedures are an improvement on strict randomization. One hundred twenty-four control children who had participated in a four year study of topically applied fluoride (H. S. HOROWITZ ET AL, IADR Program and A bstracts of Papers, No. 601, 1970), were used to evaluate the following stratification procedure: (1) Children were ordered according to base-line DMF surfaces; (2) Within each DMF surface category, they were ordered by the number of erupted permanent teeth. At least four, but no more than seven, children whose scores placed them adjacent to each other were assigned to the same stratum so that children in each of the 24 strata were as similar as possible. Fortyfour percent of the variance in four year DMF surface increments in these children could be explained by the base-line DMF surfaces and dental age. Furthermore, the four year DMF surface increments in the 24 strata were statistically different (P < 0.001, F test). Stepwise regression was used to ascertain the relative importance of variables that might be used in predicting development of new decay.

Confidence Intervals for Percentage Reductions

A method of using information from previous studies is applied to the problem of estimating treatment effectiveness of a preventive agent in terms of percentage reduction. The Bayesian statistical method allows the use of such prior information in analyzing the results of a study.

The Halcyon of Field Studies of Dental Caries Prevention, 1960-1980

I was born at just the right time-neither 20 years too soon nor 20 years too late-to take part as a clinical trial investigator during the halcyon days of studies designed to measure the effectiveness of various caries-preventive agents and regimens. When I was hired by the US Public Health Services Division of Dental Health (actually, one of its precursors) in 1960, dental decay was still rife among Americans, particularly children. Caries was ubiquitous among school-age children and a cause of widespread affliction and pain. For example, the baseline mean caries score of all children who attended a rural consolidated school in northern Pennsylvania in 1958, which was about to embark on a program of school water fluoridation, was 13.51 decayed, extracted, or filled tooth surfaces (DMFS) (Horowitz et al., 1972). In contrast, the 1986-87 national survey of US schoolchildren showed that the DMFS had dropped to 3.07 (National Institute of Dental Research, 1989). The same surveys showed that caries in approximal tooth surfaces had declined from an average of 4.78 in 1958 to 0.37 in 1986-87. Although the 1958 Pennsylvania data are not nationally representative, the findings generally conform to those of other surveys of caries prevalence done at about the same period. Mean values are inadequate to portray the morbidity of dental decay in children about 40 years ago. During dental surveys in which I participated as an examiner during the 1960s, many children who presented themselves for examination had teeth that were riddled with untreated caries, frequently with unsightly black craters in anterior teeth. Dental care was a luxury expenditure for many of the children I examined, in both rural and urban areas. Many children had severely decayed molars with hypertrophic, necrotic pulps, which caused anguish and forced them to avoid eating or brushing their teeth on the affected sides of their mouths. Those with teeth bilaterally so affected were truly tormented. It was not unusual for me to examine high school seniors whose dentitions were beyond saving and whose parents planned to provide them with dentures as a high school graduation present.

Individual Fluoridation and Fluorides for the Individual: Procedures and Results in the Control of Dental Caries

tions sufficient to produce a cariostatic effect. There are two basic approaches to the administration of fluorides: (I) s°~~.~~e~raic~ wherebv ingested fiuoride from the circulation becomes incorporated into the enamel of the developing tooth during its formation and calcification ; (2) topical) ~vherel~y post-eruptively the enamel surface of the tooth is exposed to fluoride reaching it from the mouth.