The effect on human dental caries of weekly oral rinsing with a sodium fluoride mouthwash: A final report

Arch oralBid. Vol. 16,pp. 609616, 1971. Pergamon Press. Printed in Great Britain.

THE EFFECT ON HUMAN DENTAL CARIES OF WEEKLY ORAL RINSING WITH A SODIUM FLUORIDE MOUTHWASH : A FINAL REPORT

H. S. HOROWITZ Epidemiology Branch, Dental Health Center, San Francisco, Calif. 94118, U.S.A. W. E. CREIGHTON Health Services Research Center, Kaiser Foundation U.S.A.

Statistics Unit, Epidemiology

Hospitals, Portland, Oregon,

B. J. MCCLENDON Branch, Dental Health Center, San Francisco, Calif. 94118, U.S.A.

Snmmary-A 20-month study was conducted in a non-fluoridated community to determine the caries-inhibitory effect of rinsing weekly during the school year for 1 min with 10 ml of a O-2 per cent neutral sodium fluoride solution. Subjects beginning the study were 493 white and Negro children in Grade 1 and 381 in Grade 5; each grade was equally divided into comparable test and control groups. The control groups rinsed with a placebo solution. Classroom teachers dispensed the solutions and supervised rinsing. After 20 months, 133 childrenrinsing with fluoride in Grade 1 developed 25 per cent fewer new DMm and 16 per cent fewer new DMFS than 123 controls; after 12 months, their reductions had been 34 and 30 per cent, respectively. In Grade 5,98 children who nsed the fluoride mouthrinse had 52 per cent fewer new DMfl and 44 per cent fewer new DMFS than 110 controls after 20 months. After 12 months, the 5th Grade test group had had 34 per cent fewer new DMFT and 28 per cent fewer new DMFS than controls. only the differences in Grade 5 after 20 months were statistically significant @ < 0.05). Occlusal and buccolingual surfaces received protection in Grade 1, but there were no benefits to mesiodistal surfaces. In Grade 5, all types of surfaces were protected.

INTRODUCTION

AN effort to develop effective caries-preventive procedures that are practical for widespread use in dental health programmes, various methods for the self-application of topical fluorides have been studied. Different investigators have evaluated procedures employing supervised toothbrushing (BERGGRENand WELANDER,1964; BULLENet al., 1966; CONCHIEet al., 1969), oral rinsing (TORELL and SIBERG,1962; TORELLand ERICSSON,1965; SHANNON,1966) and gel-filled mouth-pieces (ENGLANDER et al., 1967). Results have generally been encouraging. 609 A.O.B. 161~D

IN

H. S. HOROWITZ, W. E. CREI~HKIN ANDB. J. MCCLENWN

610

Of the methods investigated, a mouthrinsing procedure has the following advantages in school programmes: 1. 2. 3. 4. 5.

Little time is involved for the treatments. The technique of application is easy to learn. Few treatment materials are required. Non-dental personnel with minimal training can easily supervise the procedure. Frequent treatments can be administered easily with minimal interruption of a school’s academic programme.

A programme of weekly fluoride mouthrinsing was initiated by the Oregon State Board of Health and the Portland Public School system in the fall of 1967. Participating in the programme were children in Portland’s Head Start Programme and in Grades l-8 who attended any of nine public elementary schools serving the city’s most disadvantaged neighbourhoods. One of the principal purposes of the programme was to determine the feasibility of the mouthrinsing programme; if successful, it was planned that the programme would serve as a prototype for other programmes in the State. The administrators of the programme decided to use a O-2 per cent sodium fluoride solution and to have the children rinse weekly. The concentration of fluoride was selected on the basis of favourable results (21 per cent fewer DMF surfaces than controls) obtained by TORRELLand ERICXON(1965) with a mouthwash of the same concentration used by school children once every 2 weeks. The frequency of using the mouthwash was increased to once a week in Portland in hopes of obtaining better results than had been achieved in the Swedish study. MATERIALS AND METHOD Participants in the 20-month evaluation of the programme were children who had written parental consent in Grades 1 and 5 of the nine schools. The evaluation was made on permanent teeth. Children in Grade 1 would provide data on the effect of the procedure on first permanent molars. Children in Grade 5 were selected because most of them would erupt premolars and second molars during the study, and because they could be followed conveniently in elementary school during the study. Two U.S. Public Health Service dentists, using the DMF tooth and surface index, made the examinations. Each dentist examined about half the children in each grade. The children, while seated, were examined with a plane dental mirror, explorer and artificial light ; compressed air was available when needed. No radiographs were taken. The base line record cards in each grade were tabulated and, according to dental age (number of erupted permanent teeth), sex and previous caries experience of the children, they were assigned randomly to one of the two following study groups: Group A-To rinse in school once every month with a placebo solution containing sodium chloride. Group B-To rinse in school once a week with a 0.2 per cent sodium fluoride solution, containing approximately 0.1 per cent fluoride ion. The schedule of monthly rinsing for children in Group A was a compromise. Although it was believed to be important that they not identify themselves as controls, which would be the case if they did not rinse at all, there was a strong feeling that time and effort shouId not be invested in a procedure that would not be beneficial (weekly mouthrinsing with sodium chloride). A monthly mouthrinsing for the controls seemed to be a reasonable compromise. Because the examiners for this study had no part in administering treatments, a double-blind method could be maintained strictly. The Portland Council of Churches provided volunteers to mix the solutions in laboratories of

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WEEKLYORALRINSINGWITHASODIUMFLUORIDEhtOUTHWAsH

the Oregan State Board of Health. The solutions were delivered by staff of the State’s Dental Health Section to the schools in l-gal polyethylene bottles fitted with spring-loaded, 10 ml pumps. The only other supplies needed were napkins and small paper cups. After receiving initial instruction and training, the teachers dispensed and supervised the mouthrinsing on a continuing basis. The mouthrinsing was done by all classrooms in any given school on the same day of the week, but the days and time varied among schools. The staggered schedule enabled dental personnel of the Board of Health to visit all schools occasionally to assist in standardizing and to evaluate the regimen. The children in each classroom were given approximately 10 ml of solution in a paper cup on rinsing days and, together, they rinsed vigorously for 1 min. The rinsing was timed. After rinsing, each child expectorated into his cup, stuffed an absorbent napkin into the cup to soak up the solution and then the liquid-free cup containing the saturated napkin was disposed of in a large plastic bag. Base-line dental examinations were made in late September 1967. All children remaining in the study were re-examined one year later, and again in May 1969. No rinsing took place during the summer of 1968. RESULTS

Table 1 shows that 493 children in Grade 1 and 381 children in Grade 5 were examined on the base-line survey. After 12 months, the numbers of children remaining had dropped to 315 and 242 in Grades 1 and 5, respectively. After 20 months, only TABLE~.AVERAGENUMBEROFBASELINE GROUPANDGIUDEFORCHILDREN

DMF TEETHANDSURFACESACCORDINGTOSTUDY EXAMINEDINITL4L.LYANDFORTHosEPRESENTAFl'ER

12 and 20 MONTHs--Portland Grade 1 Study group

Children examined initially No. of children Mean DMFT Mean DMFS Children present after 12 months No. of children Mean DMFT Mean DMFS Children present after 20 months No. of children Mean DMFT Mean DMFS

Grade 5 Study group

A*

B

A*

B

246 0.65 O-83

247 0.65 0.79

190 3.44 6.36

191 3.58 6.85

164 0.69 0.87

151 0.62 0.76

114 3.53 6.78

128 3.80 7.55

135 0.75 0.97

129 0.73 0.90

112 3.44 6.48

117 3.59 6.97

*Control group.

264 children remained in Grade 1 and 229 in Grade 5. The large loss of participants reflects the transiency of the schools’ neighbourhoods. Few, if any, children left the project because of their or their parents’ dissatisfaction with it. Table 1 also shows average base-line DMF tooth and surface scores according to study group and grade for children examined initially and for those present after 12 and 20 months. Although the loss of subjects was large, the initial balance of groups

H. S. HOROWITZ,W. E. CREIGHTONAND B. J. M&LENDON

612

according to past caries experience was not altered greatly. Other data not presented show that the study groups remained well balanced by race, sex and number of erupted teeth. Even though the groups remained well balanced during the course of the study, because so many children were lost from the study, results after 12 and 20 months will be presented only for those children who were present for all examinations. Table 2 presents these findings for 256 children in Grade 1. MEAN INCREMENTAL DMF TOOTH AND SURFACE SCORES AFTER 12 AND 20 MONTHS FOR CHILDREN IN GRADE 1 PRESENT FOR ALL EXAMINATIONS, ACCORDING TO GROUP-PORTLAND

TABLE2. Nm

Teeth Study group

No. of children

After 12 months A 123 B 133 After 20 months A 123 B 133 Figures in parentheses

Mean DMFT increment

Surfaces

Difference (%)

P

Mean DMFS increment

Difference (%) P

0.53 (0.08) 0.35 (0.08)

3;o

0.12

0.98 (0.14) 0.69 (0.14)

29.6

074

0.72 (0.09) 0.54 (0.10)

25.0

0.17

1.29 (0.17) 1.08 (0.17)

16-3

020

are standard errors of the means.

After 12 months, children in Grade 1 who rinsed weekly with the O-2 per cent sodium fluoride solution developed 34 per cent fewer DMF teeth and 30 per cent fewer DMF surfaces than children in the control group. After 20 months, the percentage differences had dropped to 25 and 16 per cent, respectively. The differences in means between test and control group were not significant at a level of O-05 either after 12 or 20 months. Because Table 2 presents findings for the same children after both 12 and 20 months, one can use the data to compute the increment during the interval between 12 and 20 months. There was no evidence of cariostasis in the experimental group in the time interval between 12 and 20 months; increments of DMF teeth were identical, O- 19, in test and control groups and the test group actually developed slightly more DMF surfaces during this period than the controls ; 0 - 39 and 0 - 31, respectively. Table 3 presents findings for children in Grade 5 after 12 and 20 months. Findings after 12 months showed that children in the test group developed 34 per cent fewer DMF teeth and 28 per cent fewer DMF surfaces than controls. These percentage differences are very close to those found among first-graders after 12 months. In Grade 5, however, the benefits increased after the second school year of mouthrinsing; after 20 months, children in Group B had developed 52 per cent fewer DMF teeth and 44 per cent fewer DMF surfaces than controls. The differences between test and control groups in mean increments on both DMF teeth and surfaces after 20 months were significant at less than O-01. The calculation of caries-increment during the

A

WREKLYORALRINSINGWITH

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SODIUMFLUORIDEMOUTHWASH

TABLE 3. NET MEANINCREMENTAL DMF TOOTHAND SURFACESCORES AFTER 12 AND 20 MONTHSFOR CHILDREN IN GRADE

ALL

5 PRESENT FOR

EXAMINATIONS,ACCQRDINGTOGROUP-PORTLAND

Teeth Study group

No. of children

After 12 months A 110 B 98 After 20 months A 110 B 98 Figures in parentheses

Surfaces

Mean DMFT increment

Difference (%)

P

Mean DMFS increment

Difference (%)

0.85 (0.18) 0.56 (0.15)

34.1

O&

1.46 (0.27) 1.05 (0.24)

28.1

0;7

1.63 (0.25) 0.79 (0.17)

51.5


2.92 (040) l-65 (0.28)

43.5

KO.01

P

are standard errors of the means.

interval between 12 and 20 months shows that the children in the test group developed an average of O-23 DMF teeth, 71 per cent fewer than the O-78 DMF teeth among the controls. For the same interval, children in Group B developed an average of O-60 DMF surfaces, 59 per cent fewer than the 146 DMF surfaces among the controls. Table 4 shows findings on DMF surfaces after 20 months, according to status of tooth eruption on the base line. Groups A and B were well balanced in both Grades 1 and 5 on the numbers of teeth present on the base line and those that erupted after 1

TABLE~.MRANDMFSURFACEINCREMENIS~R~~MONTH~FORCHILDRBNINGRADES ACCORDINGTGSTATUSOPTGOTHERUPTIONONTHEBASEIINE-~RTLWD

Grade 1 A B Grade 5 A B

No.

Mean Difference DMFS (%) increment

5

Teeth erupting during study

Teeth present on base line Study Group

AND

p

No.

Mean Difference DMFS (%) increment

P

5.8 5.5

1.03 0.93

9.7

026

5.4 5*5

0.26 0.15

42;

0.20

19.9 19.3

2.38 1.48

37-8

0.04

5.4 5.0

0.54 0.16

70.4

0%

the study began. The findings indicate that the protection was relatively greater in both grades on teeth that erupted after the study began than on teeth present in the mouth at the time of the base-line examinations. In Grade 1, the reduction on erupting teeth was 42 per cent compared with only 10 per cent on teeth present on the base line.

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H. S. HOROWITZ,W. E. CREIGHTONAND B. J. MCCLENDON

Grade 5

FIG. 1. Mean DMF surface increments

after 20 months according to grade, study group and type of surface--Portland.

For Wth graders, the respective reductions were 70 and 38 per cent. The differences in means between test and control groups in Grade 5 were significant at 0.04 for both categories of teeth. Depicted graphically in Fig. 1 are mean DMF surface increments after 20 months according to type of surface; that is, occlusal, buccolingual and mesiodistal. Children who used the fluoride mouthrinse in Grade 1 received slight protection on occlusal and buccolingual surfaces but developed slightly more carious mesiodistal surfaces than controls. Children in the test group in Grade 5, however, received protection on all categories of surfaces. DISCUSSION

No definite reasons can be given for benefits apparently improving with time in Grade 5 but decreasing with time in Grade 1. Perhaps the inconsistent fmdings are related to the fact that so few permanent teeth were in situ (between 5 and 6) among children in Grade 1 when the study was initiated. Also, knowledge of age-specific

WEEKLY

ORAL

RINSING

WITH

A SODIUM

FLUORIDE

MOUTHWASH

615

patterns of dental caries attack dictates that most decay in children in Grade 1 occurred on first molars. This tooth may have responded less than other teeth to the mouthrinsing with a sodium fluoride solution because of its high susceptability to decay. Personnel associated with this investigation were impressed by the ease with which large numbers of children could be treated easily with minimal interference with the schools’ academic programmes. The weekly rinsing required, on average, only a few minutes per week to accomplish in each classroom. The mouthrinsing programme as done in the present study was very economical. Supervisory dental personnel were already employed by the Oregon State Board of Health. Volunteers prepared the solutions and, of course, the teachers and other school personnel associated with the programme volunteered their services. The cost and extent of supplies and materials were minimal. Supplies consisted initially of a large dispensing bottle with a calibrated pump and a waste container for each classroom. Needed weekly for each child were a paper cup, paper napkin and 10 ml of solution. The cost of supplies and materials for the weekly treatments has been estimated at 31 cents per child, per year. In conclusion, the investigators are encouraged by the results of this study and believe that mouthrinsing with fluoride solutions in school is an effective, feasible dental public health preventive procedure. Additional studies must be done, however, to determine optimal concentrations of solutions and optimal, practical frequencies of application. Acknowledgements-The authors wish to thank Dr. DAVID M. WITTER, JEANNE Fox and CHERYLSMITHof the Dental Health Section, Oregon State Board of Health and Messrs. WILL FLETCHERand HAROLD KLEINER of Portland, Oregon’s Public Schools for their cooperation and assistance during this study,

R&um&Une etude de 20 mois a BtBr&aliskedam une cite non fluor&, pour determiner I’action d’inhibition de la carie d’un bain de bouche hebdomadaire, applique pendant une minute, avec 10 ml dune solution de fluorure de sodium neutre a 0,2% chez les enfants des ecoles, sous la supervision de leurs maitres. Les tleves sont des enfants des classes 1 et 5, &pares en groupes experimental et temoin. Le groupe temoin rince avec une solution placebo. A la fin de Etude, les enfants des classes 1 et 5, utilisant le bain de bouche fluore, presentent respectivement moins de 16 % et 44 % de surfaces carieuses par rapport aux temoins. Settle la difference observee chez les enfants des classes 5 est significative. Zusammeufassung4.n einer nichtfluoridierten Gemeinde wurde ein 20-MonateVersuch durchgeftihrt, urn die karieshemmende Wirkung einer wiichentlichen Spiihmg mit lOm1 einer 0,2 %neutralen NatriumfluoridlGsung zu bestimmen; diese Sptilung wurde in der Schule eine Minute lang unter Aufsicht des Lehrers durchgefiihrt. An diesem Versuch nahmen Kinder der Klassen 1 und 5 teil, die in vergleichbare Versuchs- und Kontrollgruppen verteilt wurden. Die Kontrollen sptilten rnit einer Placebo-Losung. Beim AbschluD des Versuchs hatten die Kinder in den Klassen 1 und 5, die mit Fluorid gesptilt hatten, 16% bzw. 44% weniger karitise Obertlachen als die entsprechenden Kontrollen. Statistisch signifikant war nur der Unterschied bei der Klasse 5.

616

H. S. Ho~owrrz. W. E. CREIGHT~NAND B. J. MCCLENDON REFERENCES

BERGGREN, H. and WELANJXR,E. 1964. The caries-inhibiting effect of sodium, ferric and zirconium fluoride. Acta o&t. Scand. 22,401-413. BULLEN,D. C. F., McCOMBIE,F. and HOLE,L. W. 1966. Two-year effect of supervised toothbrushing with an acidulated fluoride-phosphate solution. J. Can. dent. Ass. 32,89-93.

J. M., McCor+rma,F. and HOLE,L. W. 1969. Three years of supervised toothbrushing with a fluoride-phosphate solution. J. Publ. Hlth Dent. 29, 11-18. ENGL,ANDER, H. R., KEYES,P. H., Gmrwrcrrr, M. and SULTZ,H. A. 1967. Clinical anticaries effect of repeated topical sodium fluoride application by mouthpieces. J. Am. dent. Ass. 75, 638-644. SHANNON,I. L. 1966. Effect of whole saliva in performance of O-1 per cent stannous fluoride mouthwash. USAF Sch. Aerospace Med. Pub., July. TORELL,P. and ERI~N, Y. 1965. Two-year clinical tests with different methods of local cariespreventive fluorine application in Swedish school children. Acta o&t. Scand. 23,287-322. TOIULL,P. and S~BERG, A. 1962. Mouthwash with sodium fluoride and potassium fluoride. Odont. Reey 13,62-72. CONCHE,