A GREAT niass of evidence has accumulated on the benefits, safety and practicability

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1 Addition to Milk and Its Effect on Dental Caries in School L. L. RUSOFF, PH.D.,* B. S. KONIKOFF, D.D.S., M.S.,t J. B. FRYE, JR., PH.D., J. E. JOHNSTON, PH.D. AND W. W. FRYE, M.D., PH.D. A GREAT niass of evidence has accumulated on the benefits, safety and practicability of fluoridation of the public drinking water in the partial prevention of dental caries of children. Fluoridated water at optimal levels of. to.2 ppm. has inhibited dental caries as much as per cent, particularly when ingested during the growing period of the permanent teeth at the time of enamel calcification. This appears to be one of the most effective means of preventing dental caries. The literature on this subject up to 952 was reviewed by the National Research Council. Since then, numerous reports and studies on the benefits and safety of fluoridated water have been published in this country and abroad and the results have been summarized in a few publications.25 It is estimated that about half the people in the United States do not live in areas served by community water supplies and have to rely on well water; also, unfortunately, too few community water supplies have been fluoridated.4 The necessity of finding for these areas, not a substitute, but an adjunct or alternative to the fluoridated water program was therefore apparent. It was reasoned that milk should be an obvious choice as a new vehicle for fluoride since it is the food most universally used by pregnant women, infants and children during From the Dairy Science Department and the Medical School, Louisiana State University, Baton Rouge, Louisiana and New Orleans, Louisiana. * Nutritionist, Dairy Science Department; t Project Dentist; Head, Dairy Science Department; Physiologist, Dairy Science Department; Vice-President and Dean, Medical School. This paper was presented in part at the Fifth International Congress on Nutrition, Washington, D. C., September, 96. period of tooth formation. Milk is an excellent source of the biologically-available calcium and phosphorus which, along with vitamin D, are required in the diet for strong teeth and bones.67 In 953, Light8 reported on the value of milk in increasing the fluoride, alues in the placenta. The daily amount of milk and water consumed by pregnant women who had access to fluoridated municipal water was recorded. It was found that greater consumption of fluoridated water had no effect on increasing fluoride values and that the fluoride values in the placenta paralleled the milk intake and not the fluoridated water intake. In 952, the idea of using milk as a vehicle for fluoride was considered since our municipal water supply in Baton Rouge was not fluoridated and contained only. to.2 ppm. of fluoride.9 The objectives of this study were to determine the effect on dental caries of fluoride added to milk in the school lunch program over approximately a four-year period and to determine any carry-over effect of the fluoridated milk on dental caries eighteen months after treatment was stopped. EXPERIMENTAL Almost three years were spent working out the mechanics and problems attendant to the starting of this study. Meetings were held to acquaint parents with the objectives and to acquire written permission from them for their children to participate. Scheduling details were worked out with the school principals, and other arrangements were made with city health officials and the Louisiana Sixth District Dental Society. Transportation was furnished by the East Baton Rouge Parish Public School Board. Schedule coordination was a major Downloaded from ajcn.nutrition.org at PENNSYLVANIA STATE UNIV PATERNO LIBRARY on September 8, 2 American Journal of Clinical Nutrition 94 Vol., August 962

2 Addition to Milk and Dental Caries 95 Dental Caries Incidence of First Molar Teeth at the Beginning of the Experiment (956) and After Three and One- Half Years of Fluoridated Milk Administration I No. of 956 Average % of DMF before 959 Average % of DMF after Average % Increment of DMF ( ) S * P <.. 2 problem. It required the whole hearted cooperation of all the participants before the project could be initiated. In October 955, a controlled experiment was set up initially using 7 children, ages six through nine years, in grades through 4 in two neighboring schools, approximately three miles apart. Each age gr#{248}pconsisted of approximately twenty students with almost equal sex distribution. The children attending the Louisiana State University Laboratory School were designated the treated group. They were served a half pint of fluoridated milk daily with their school lunch for approximately a four-year period. The fluoridated milk consisted of homogenized milk fortified with a minute prophylactic dose of mg. of fluoride in the form of analytical reagent sodium fluoride (2.2 mg.) per half pint. One-half cubic centimeter of solution containing mg. of fluoride ion was added daily to each half pint container of homogenized milk prior to sealing. There was no difference in taste, color or odor of the fluoridated milk when compared with the Unfluoridated milk. The parents of the treated children voluntarily permitted the Serving of fluoridated milk to their children. During the summer vacation periods the parents of the treated children were given bottles containing an aqueous solution of sodium fluoride so that 8 drops in an 8 ounce glass of milk furnished the level of mg fluoride ion daily. from the Highland Elementary School were designated the control group and were served homogenized milk without fluoride addition daily * * Familial backgrounds of both groups of children were similar in sociological, educational and financial status ; all children lived in the same area. The two groups of children were not given a special diet and no specific brushing or care of the teeth was recommended. It was particularly stressed to the parents of the treated children that no topical application of fluorides to the teeth be allowed. Dental examinations, which included visual examinations and x-ray films of the teeth of all the children, were made in March 956, six months after the initiation of the experiment, and annually thereafter through March 959 by local dentists at the East Baton Rouge City Parish Health Unit. The final dental examination was made in December 96, eighteen months after cessation of fluoridated milk administration (June 959) and twenty-one months after the 959 dental examination. All children were brought to the East Baton Rouge Health Unit in school buses. Examinations were conducted in the Dental Division in standard dental chairs with the use of mouth mirrors, fine pig-tail explorers, compressed air and artificial lights, and supersensitive bite-wing x-ray film exposed for.25 seconds. In 959 and 96, four dentists and the project dentist made examinations of the children. The same two dentists checked and charted the mouth of each child while the other two dentists took x-ray films of teeth during both examinations. When questions arose concerning dubious #{23},arious areas, the project dentist made the final decision and, for verification, made use of magnifying glasses of 2 /4 power at a focal length of 8 inches. Downloaded from ajcn.nutrition.org at PENNSYLVANIA STATE UNIV PATERNO LIBRARY on September 8, 2

3 96 Rusoff, Konikoff, Frye, Johnston and Frye 959 Dental Caries Incidence of Erupted Permanent Teeth (Second Molars, First and Second Bicuspids) After Three and One-Half Years of Administration II No. of Average No. of Average No. of DMF Teeth per Child % DMF 9 2 All * P <.5. t P < Individual charting of the teeth was made on a form similar to that recommended by the American Dental Association Committee to Standardize Checking The dental examiners had no knowledge of the group being checked. All x-ray films were developed by the project dentist using standard time and temperature in a refrigerated developing tank and a film dryer. The films were checked against individual charts by two of the examining dentists and the project dentist to assure accuracy of recorded results. Numbers were used to identify films so as to eliminate examiner bias. Statistical analyses of the data were made according to the methods of Snedecor RESULTS Data on deciduous teeth were not used since these teeth were not present at the end of the fluoridated milk feeding period. Table i presents the dental caries incidence of the first molar teeth on a per child basis at the beginning of the experiment (956), and after three and a half years of fluoridated milk administration ( 959). The average percentage increments of DMF (decayed, missing or filled) teeth at the end of this period, which were calculated as the proportion of noncarious teeth that became carious at the end of the milk feeding period, were lower in the treated group than in the control group at all ages, with the exception of the twelve year old children. The increment * t 27. values were versus 83.8 per cent, 62.2 versus 73.4 per cent, 25. versus 5.() per cent, and versus 5.92 per cent, respectively, for children at nine, ten, eleven, and twelve years of age. The over-all average for all ages (total) was versus per cent. The differences between these percentages at the various ages were tested using the t test. This standard binomial procedure was significant between the values for the nine year old children at P<.. The differences in percentage for the ten, eleven and twelve year old children were not significant. However, the difference between the over-all averages for both groups was found to be highly significant at P<.. Table ii shows the 959 dental caries incidence of the erupted permanent teeth (second molars, first and second bicuspids) for both groups of children on a per child basis. These teeth had not erupted when the experiment was initiated in 956. The cuspids are not included since no caries were found as would be expected. It can be observed that the percentages of DMF teeth per child of the treated group at the various ages were lower than those of the control group, the values being 3.69 versus. per cent, versus 2.6 per cent, 4.46 versus 8.2 per cent, and.2 versus 48. per cent, respectively, for children, ages nine Downloaded from ajcn.nutrition.org at PENNSYLVANIA STATE UNIV PATERNO LIBRARY on September 8, 2

4 Addition to Milk and Dental Caries Distribution of Number of Carious Surfaces of Erupted Permanent Teeth (Second Molars, First and Second Bicuspids) After Three and One-Half Years of Administration III No. of Total No Teeth No. of Teeth with to 3 Carious Surfaces Total No. Carious Teeth AllI through twelve years. The over-all average of DMF teeth per child for all ages for the children who had consumed fluoridated milk was 5.59 per cent as compared to 27. per cent for the control group. The difference of approximately five times as many caries in the control group over the treated group was found to be highly significant (P<.) when tested by the t test. The differences between the percentage caries rates for the various ages of children in the two groups was not significant when examined by the t test with the cxception of the twelve year old children who showed a significant difference at the 5 per cent level of probability. Table in gives the 959 distribution of the number of carious surfaces of the erupted permanent teeth for both groups of children at the various ages nine to twelve years showing the trend in favor of the treated group. The possible carry-over effect of the ingestion of fluoridated milk on the children s teeth eighteen months after cessation of fluoride administration is presented in Table v. The percentages of DMF teeth per child for both groups of children of the various ages are again lower in the treated group. The values for children at eleven years of age was 4.8 versus 4.7 per cent, the difference being significant at P<. ; the difference for the values found for the fourteen year old children, 36.9 versus 74.2 per cent was significant at P <.5. The difference in the values for the other two age levels was not significant. The over-all average for all ages of children in the treated group was 23. per cent as compared to 48.7 per cent for the control group, which was highly significantly different (P <.) when analyzed by the t test. The average percentage increments of DMF teeth per child after eighteen months cessation of fluoride administration, which was calculated as the proportion of noncarious teeth in 959 which became carious in 96, was lower for all ages in the treated group. The youngest group of eleven year old children who had ingested fluoridated milk at the earliest age of six years showed the greatest difference in percentage increment, 4.3 as compared to per cent for the children in the control group, but this difference was found to be statistically insignificant. However, the over-all increment averages of 2.5 per cent for the treated group versus the per cent value for the control group was significant at P <.5. Table v gives the 96 distribution of the number of carious surfaces of the erupted permanent teeth for both groups of children Downloaded from ajcn.nutrition.org at PENNSYLVANIA STATE UNIV PATERNO LIBRARY on September 8, 2

5 98 Rusoff, Konikoff, Frye, Johnston and Frye 96 Dental Caries Incidence of Erupted Permanent Teeth (Second Molars, First and Second Bicuspids) and Perceiitage of DMF Increment Eighteen Months after Cessation of Administration IV No. of Average No of Average No. of DMF of Teeth per Child DMF Teeth per Child Average % Increment of DMF Teeth (959-96) per Child All * P <.. t P <.5. P < All V * f Distribution of Number of Carious Surfaces of Erupted Permanent Teeth (Second Molars, First and Second Bicuspids) No. of (eleven to fourteen years of age) at the end of the five year experimental period. The trend in favor of the treated group is still evident. COMMENTS It should be pointed out that the number of children at chronological dental examinations varied because of unavailability due to illness, moving out of town and other reasons. However, the actual number of children listed in I Total No. Teeth f No. of Teeth with to 4 Carious Surfaces Total No. Carious Teeth the tables were those who participated during the entire experimental period. The average percentage increments of DMF first molar teeth for both groups of children between the initial dental examination in 956 and after three and a half years of fluoride administration, show a highly significant difference (P <.) in favor of the treated children, age nine (formerly age six, Table i). The values for the treated children (37.33 per cent) and Downloaded from ajcn.nutrition.org at PENNSYLVANIA STATE UNIV PATERNO LIBRARY on September 8, 2

6 Addition to Milk and Dental Caries 99 the control children (83.8 per cent) of this age are more striking when it is seen that the initial caries incidence in 956 prior to fluoride administration was higher for the designated fluoride group (29.63 per cent DMF teeth per child) as compared to the control group (.36 per cent DMF teeth). The values were reversed after 3 /2 years of fluoridated milk administration in 959, being 53.2 and per cent, respectively. The over-all percentage increments of DMF teeth per child for all ages show the same trend, the values being and per cent, respectively, for the treated and control groups. The difference between these values was statistically significant at the per cent level of probability. Thus, the ingestion of fluoridated milk appears to be of value in resistance to caries in very recently erupted teeth. In studies with fluoridated water, Hayes et 2 have indicated that fluoride ingestion after a period of years might reduce caries increase in permanent teeth recently erupted prior to fluoride usage. McClure and Likins 3 observed that teeth of individuals who had regularly ingested fluoridated water at a level of. to.2 ppm. (Aurora, Illinois) had 3 per cent more fluoride in the enamel and 6 per cent more fluoride in the dentin than was found in the teeth formed in persons living in places where there was little or no fluoride in the drinking water. It is possible, therefore, that in recently erupted teeth the apices of the roots are not completely calcified and thus the circulation to the pulpal blood vessels is less impeded than at a later date when the apex completely forms and closes to a small opening. With this comparatively large amount of circulation to the pulpal vessels, it is conceivable that a continuation of the fluoride ion metabolism results in a more dense dentin thereby increasing the resistance to bacterial invasion, reducing dentin solubility in bacterial acids, thereby limiting the depth and extent of carious lesions. Further study is necessary to confirm this. Also, Grainger and Coburn 4 have suggested that since the enamel of teeth has been demonstrated to be permeable from the pulpal side, fluoride ions might diffuse from the dentin side of the enamel and might be incorporated chemically into the matrix during the final stages of calcification, thus increasing resistance to caries. The 959 caries incidence of new permanent teeth (second molars, and first and second bicuspids) erupting after the initiation of the experiment is lower for the treated group at all ages as compared to the control group (Table ii). The differences in percentages of DMF teeth per child at ages nine through eleven years between both groups were not statistically significant, whereas the difference between the values for the twelve year old children was significant at the 5 per cent level of probability. The small number of children in each age class probably accounts for the nonstatistical significance. The average over-all percentage of DMF teeth per child for all ages was 5.95 per cent for the treated group and 27. per cent for the control group which is approximately 5 times more caries in the control group than in the treated group. Since the difference between these values was found to be highly significant (P <.), the ingestion of fluoridated milk prior to the eruption of teeth appears to be of definite value in reducing dental caries in young children. Careful checking of the teeth revealed no evidence of any mottling in the treated groups. It should be understood that, because of the shape of the crowns, cuspid teeth are less amenable to dental caries, and since none of the erupted permanent cuspids in either group were carious, they were not included in the table. The possible carry-over effect of fluoride administration, eighteen months after cessation of fluoride ingestion, as observed in Table iv, shows that the 96 dental caries incidence of both groups of children, at all ages, follows the same pattern as the values for the 959 data. The difference between the average over-all percentage of 96 DMF teeth (second molars and first and second biscuspids) per child for the treated group (23. per cent) and for the control group (48.7 per cent) was also highly significant at the per cent level of probability. The percentage increments of DMF teeth between the 959 and 96 values which accrued in the eighteen months after cessation of fluoride treatment and twenty-one months Downloaded from ajcn.nutrition.org at PENNSYLVANIA STATE UNIV PATERNO LIBRARY on September 8, 2

7 Rusoff, Konikoff, Frye, Johnston and Frye between dental examinations, are lower in the treated group than in the control group, the percentages being 4. 3 versus per cent,. versus 29. per cent, 2.53 versus per cent and 3.3 versus per cent, respectively, for the treated and control children, ages eleven to fourteen years (formerly six to nine years). The over-all average values are 2.5 per cent for the treated group and per cent for the control group. The difference in increment percentages of the overall values was statistically significant at P<.5 thus indicating that the percentage reduction of dental caries in the treated group was maintained during this period. The optmmal level of fluoride ion in the drinking water has been agreed upon as ppm. or mg. fluoride per The estimation that school children would consume approximately L. of water daily would set the optimal level of fluoride intake at mg. fluoride daily. One milligram of fluoride ion daily in a half pint of milk (school lunch) should supply the optimal prophylatic dose. One quart of milk is the recommended minimal daily requirement for growing children in the United States.6 When market milk is consumed in addition to the half pint of fluoridated milk, the level of fluoride, on the basis of a quart of milk, amounts to approximately ppm. fluoride. Prior to the initiation of the experiment the question arose as to whether the calcium in the milk would form an insoluble precipitate with the fluoride. Microscopic tests failed to show any sedimentation. The results obtained in the present study also reveal that the fluoride ion in fluoridated milk is biologically available since a significant reduction in dental caries was obtained. Ziegler 5 reported that the solubility of CaF2 in water at 8#{76}c.is mg. fluoride per L. and that the hydrochloric acid of the stomach increased the solubility of CaF2 twenty times as much. He also found that the feeding of fluoridated milk to pregnant women caused an increase in the fluoride level of mothers blood, of the placenta and of mothers milk. In 958, Ericsson, 6 using the radioactive fluoride isotope, F, for studies on the state of fluorine in milk, found no appreciable sedimentation of fluorine compounds up to 4.2 p.p.m. of fluorine in milk on standing for five hours. Only trace quantities of F 8 were found bound to the fat and the albuminglobulin fractions of milk. The casein contamed less than one fourth of the F 8 content in whole milk. Ericsson stated the utilization of the fluorine in milk does not seem to be so incomplete as to prevent milk from being used as a vehicle, in the first rank in areas where the drinking water cannot be fluoridated. The benefical results obtained in this study by the use of fluoridated milk in the prevention of dental caries in young children are similar to published reports on the results of fluoridated water consumption. This carefully controlled experiment was executed on a small segment of the population and is a pilot study. Public health studies with large numbers of younger children and infants using fluoridated milk during calcification of the teeth and prior to eruption, and also in school lunch programs under careful supervision, are recommended for future research. SUMMARY In a pilot study, the effect on dental caries of milk as a vehicle for fluoride administration was determined in young children in a school lunch program over approximately a four-year period. A half pint of fluoridated milk supplying mg. of fluoride ion in the form of sodium fluoride was given to young children, initial ages six to nine years in grades through 4. Two groups of children, a treated and control group, from two neighboring schools initially involving 7 children (approximately twenty per age level per group) were selected for this study. Local dentists, under the supervision of the project dentist, examined the children clinically and roentgenographically during the study. Examinations were conducted each year during the administration of fluoridated milk, and also eighteen months after cessation of fluoridated milk ingestion. At the end of three and a half years of ingestion of fluoridated milk, a significant reduction of approximately 7 per cent in caries incidence of teeth erupting since the initiation of the experiment (first and second bicuspids and Downloaded from ajcn.nutrition.org at PENNSYLVANIA STATE UNIV PATERNO LIBRARY on September 8, 2

8 Addition to Milk and Dental Caries second molars) was obtained for the treated group (sixty-five children) as compared to the control group (sixty-four children). Eighteen months after cessation of fluoride ingestion, a significant difference of approximately 5 per cent in caries rate was retained in favor of the treated group ; also, a significant reduction in caries increment for the treated group during this interval indicated a carry-over effect for the fluoridated milk. There was also an indication that fluoridated milk administration appears to be of value in reducing caries rate in newly-erupted first molars. This study again demonstrates that the ingestion of a recommended level of fluoride ion during calcification of teeth and prior to eruption is of value in increased resistance to dental caries. ACKNOWLEDGMENT We are indebted to Dr. John L. Garrett and Miss Geraldine Wall, Principals of the Louisiana State University Laboratory School and Highland Ele,nentary School, respectively, and to the East Baton Rouge School Board for their wholehearted cooperation during the years of the experiment; to Dr. David Brown, Head of the East Baton Rouge Parish Health Unit for permission to use their dental facilities; to the members of the Sixth District Dental Association who gave freely of their time in the dental inspection of the school children; and to Dr. B. R. Farthing, Louisiana Agricultural Experiment Station statistician, for counsel in the statistical analysis of the data. REFERENCES. A Survey of the Literature of Dental Caries. National Research Council Publication 225. Washington, D. C., Expert Committee on Water Fluoridation. Internat. Dent. J., 8: 78, World Health Organization. Expert Committee on Water Fluoridation. First report. Technical report series, No. 46, pp. 7, 8, 7, 2. Geneva World Health Organization, Division of Public Health, Bureau of State Services, Public Health Service Report on Fluoridation in the United States. Pub. Health Rep., 74 (6): 53, KONI.KOFF, B. S. Milk as a vehicle for NaF for the Prevention of Dental Caries in. M. S. Thesis, 96. Louisiana State University. 6. RUSOFF, L. L. The miracle of milk. J. Dairy Sc., 38: 7, SHAW, J. H. Studies on the influence of dairy products on development and maintenance of teeth. Nutrition News, February LIGHT, A. E. Fluorine intake with relation to milk and water consumption. Arch. Biochem., 47:477, SuMz, D. Baton Rouge Water Works Co., Personal Communication, Clinical Testing of Dental Caries Preventives- Report of a Conference to Develop Uniform Standards and Procedures in Clinical Studies of Dental Caries, p. 6, appendix E. Chicago, Ill American Dental Association Committee.. SNEDECOR, G. W. Statistical Methods, 5th ed. Ames, Iowa The Iowa State College Press. 2. HAYES, R. L., LITTLETON, N. W. and WHITE, C. W. Posteruptive effects of fluoridation in first permanent molars of children in Grand Rapids, Mich. Am. J. Pub. Health, 27: 92, McCLum, F. J. and LIKINS, R. C. Fluorine in human teeth studied in relation to fluorine in the drinking water. J. Dental Res., 3: 72, GRAINGER, R. M. and COBURN, C. I. Dental caries of the first molars and the age of children when first consuming naturally fluoridated water. Cana.d. J. Publ. Health, 46: 347, ZIEGLER, E. tyber die Milchfluorierung. Bull. Schweiz. Akad. med. Wissensch., 2:466, ElucssoN, Y. The state of fluorine milk and its absorption and retention with radioactive fluorine. Acta odont. Scandinav., : Downloaded from ajcn.nutrition.org at PENNSYLVANIA STATE UNIV PATERNO LIBRARY on September 8, 2