Community Dent. Oral Epidemiol. 1976: 4: 240-243 (Key words: dental caries; fluorides; phosphate)

Effect of topically applied acidulated phosphate fiuoride on dental caries MOHAMED ZAHRAN

Dental Research Center, Ministry oj Health, Cairo, Egypt ABSTRACT - A 4-year clinical trial was conducted to determine the effect on dental earies ineidence of the use of acidulated phosphate fluoride (APF 1.23 % ) . 1,653 Egyptian schoolchildren aged 8 years started the trial. Dental caries was assessed annually by clinical examinations. 1,027 children completed the study. After 4 years, the children in the study group showed a mean of 2.58 DME teeth and 2.68 DMF surfaces. Those in the control group showed 2.58 and 2.67, respectively. No significant reduction in the caries increment was observed at 0.05 level. The findings of this study suggest that topical application of fluoride does not decrease pit and fissure caries. . (Received jor publication 2 February, accepted 23 May 1976)

It has been documented that several fluoride-containing agents, when applied topically, effectively reduce the incidence of dental caries'-"'"'". The observation by BRUDEVOLD, SAVORY, GAVDNER, SPINELLI & SpEtRs' that enamel acquires more from a solution of fluoride acidulated with phosphoric acid than from an equivalent solution of stannous fluoride or from neutral fluoride encouraged us to undertake a clinical study designed to test the caries-reducing effect of the topical application of acidulated phosphate fluoride in a geographic area where dental caries is mostly limited to pits and fissures. A low prevalence and incidence of dental caries with slow progression is a notable characteristic of the caries development pattern in Egyptian schoolchildren. Previous studies indicate that the mean DMF at age 7 is 0.5 and at age 13, 3.2. All cavities up to that age are of the simple pit and fissure variety while the front teeth are almost immune to caries^". This pattern of dental caries experience and the encouraging results of initial investigations with professional application of acidulated phosphate fluoride prompted us to initiate the study reported here, as a further test of the efficacy of this agent in an area near Cairo, where the fluoride in the drinking water is 0.2 parts/10°.

DESIGN OF STUDY When the project was started, Badrashien, a rural area near Gairo, was chosen as the site for the study. The population studied consisted of the second-grade children attending the elemeiilary schools in the area. Twenty-four schools accommodating 1,653 children of ages ranging from 7 to 9 years were included in the program. Thirteen out of the 24 schools were chosen at random and the children in these schools made up the study group. All participants in the 24 schools received an annual examination and were included in an incremental dental care program reported earlier'". Acidulated phosphate fluoride (2 % sodium fluoride and 0.15 M phosphorie acid, pH 3.2) was applied twice a year to the children in the 13 study schools. The children in the other 11 schools received all dental services except the preventive program and acted as the control group. The solution was applied by trained hygienists under the supervision of a dentist. Before application, teeth were scaled to remove calculus and coronal surfaces of teeth were polished with a motor-driven rubber cup and fine pumice paste with glycerin. The prepared teeth were isolated with cotton rolls, and dried with compressed air to facilitate adequate drying of the interproximal tooth surfaces. The fluoride solution was applied with a cotton applicator for 3 min. All four quadrants were treated in one visit. Ghildren were instructed not to rinse the mouth, eat, or drink for at least 30 min after treatment. After calibration, two dentists carried out the dental examinations, utilizing plain mouth mirrors, standard probes, and direct sunlight. Each year, every child who remained in the study was reexamined. To avoid ex-

Effect of acidulated phosphate fluoride 241 Table 1. Initial age, number of erupted permanent teeth, a n d past caries experience of continuous participants for experimental and control groups

Group Study Control

No. of children

Mean age, years

579 448

8.4 8.3

Erupted DMFT, teeth, mean mean 1.14 1.07

8.1 8.0

DMFS, mean 1.25 1.20

aminer bias, new forms were used for all reexaminations. T w o mobile dental buses were used to carry out the program with the ehildren at their schools.

RESULTS

• ..

Xhe findings are based on a final study population of 1,027 children. At the end of the study, 579 children in the experimental group and 448 children in the control group had presented for every examTable 2. Tooth and surface increment during the study period Mean increments

Base line Study Control

DMF teeth

DMF surfaees

1.14 1.07

1.25 1,20

1st reexamination Study Control % difference

0.33(0.06)* 0.33(0.04)* 0.32(0.03)* 0.23(0.07)* 3.0 7.5

0.83

2nd reexamination Study Control % difference

0.32(0.04)* 0.34(0.03)* 0.38(0.06)* 0.40(0.08)* 17.5 18.6

1.59

3rd reexamination Study Control % difference 4th reexamination Study Control % difference

.

Table 3. Caries increment after 4 years for the experimental and control groups

Group

0.37(0.06)* 0.36(0.07)* 0.40(0.03)* 0.42(0.06)* 16.5 8.1

0.53

0.42(0.08)* 0.40(0.07)* 0.41(0.05)* 0.42(0.04)* 2.3 5.0

0.65

* Standard error of the mean. *» t = 1.96 at 0.05 level of significance.

ination and treatment. All findings reported below pertain to these subjects, who were present at the initial and all follow-up examinations. This number reflects an attrition of approximately 37 % of the 1,653 children who were present for the baseline examination. This child attrition rate over the 4year test period is well within the acceptable range of participant loss for a long-term clinical trial of this nature. An analysis of the baseline characteristics of the 1,027 children who completed the study showed a well-balanced population with no significant differences in age, number of erupted teeth, or past caries experience as shown in Table I. Data relevant to caries increments at the end of each year of the study are summarized in Table 2. This Table shows the incretiiental scores for the DMF teeth and surfaces of the children completing the 4-year study. The incremental seores combine findings for teeth present at the time of baseline examination and for teeth erupting during the study. Although after 3 years there is a slight and statistically nonsignificant decrease in incremental DMF teeth and surface scores of 18.6 and 17.5 % respectively, 1 year later, the corresponding percentage difference was very slight and statistically nonsignificant and in favor of the control group. Table 3 shows the mean DMF teeth and surfaces at the beginning of the study and at the end of 4 years, for both the experimetital and the control groups. It is clear that at the end of the study and after nine applications of APF, children of the experimental group experienced DMF scores for teeth and surfaces very similar to those of the controls.

5th Base- exami- Increment, line nation. mean mean mean

Difference,

t

/o

DMF teeth Study Control

1.14 1.07

2.58 2.58

1.44(0.08)* 1.51(0.09)*

4.5

0.75**

DMF surfaces Study Control

1.25 1.20

2.68 2.67

1.42(0.07)* 1.47(0.08)*

3.0

0.63**

* Standard error of the mean. ** not significant at 0.05 level.

242

ZAHRAN

All the observed differences during the study period were inconsequential and could easily have occurred by chance.

reported that the occlusal surface of children's teeth receives less protection from water fluoridation than the smooth surfaces, which is in agreement with the present study. Similar findings are published for posteruptive exposure to topically applied fluoride DISCUSSION solutions and dentifrices'* ""*''^°~"''^ This may explain the disappointing results of the topical appliFindings from this study of the topical application of acidulated phosphate fluoride solution are dis- cation of APF in reducing caries increment in Egyptian schoolchildren. appointing. The data fail to show decay-preventing effect on newly erupted teeth of a 1.33 % acidulated phosphate fluoride solution applied nine times at 6-month intervals over a period of 4 years. PreREFERENCES vious studies have shown that professional applica1. BACKER-DIRKS, B.: The relation between the fluoridation of APF reduced caries increment by about 30— tion of water and dental caries experience. Int. Dent. 40 %, and according to HOROWITZ" acidulated J. 1967: 17: 582-605. 2. BRANSBY, E . R . , FORREST, J. R. & MANSBRtDGE, J. N.: phosphate fluoride is the agent of choice for proDental effects of fluoridation of water. Froe. Nutr. Soc. fessional application. When planning our preventive 1963: 22: 84-91. program, it was hypothesized that biannual topical 3. BRUDEVOLD, F., SAVORY, A., GAVDNER, D . E . , SPINELLI, application of APF for long periods, 4 years, would M. & SPEIRS, R . : A study of acidulated fluoride solureduce effectively the caries increment among the tions. I. In vitro effects on enamel. Arch. Orat Biol. 1963: 8.- 167-177. primary schoolchildren in Egypt. This assumption 4. DEPAOLA, F . F . : A review of clinieal trials utilizing was based on the published results of clinical tests acidulated phosphate fluoride topical agents. / . Am. which agreed on the following points regarding topColl. Dent. 1968: 23: 22. ical fluoride application"'. : 5. ELIZABETH, A. F.: The effect of fluoride dentifrices on the caries incidence of individual tooth surfaces. Aust. /. The use of fluorides in topical applications, apDettt. J. 1971: 12: 187-190. plied by recommended procedures, is beneficial in 6. FRANKL, S. N , , FLELSCH, S. & DIODATI, R . R . : The reducing the caries increment in caries-susceptible topical anticariogenic effect of daily rinsing with an individuals in fluoridated and nonfluoridated areas. acidulated phosphate fluoride solution. / . Am. Dent. 2. The anticaries effect of any fluoride preparaAssoc. 1972: ^5: 882-886. 7. HOROWITZ, H . S,: Effect on dental caries of topically tion is improved the more frequent the application. applied acidulated phosphate fluoride: results after two 3. The prolonged effect of topical fluoride appliyears. / . Am, Dent, Assoc, 1969: 7^: 568-572. cation generally is not seen beyond 2-3 years. 8. HOROWITZ, H . S.: The current status of topical fluoride Findings of our study stand in contrast to the in preventive dentistry. In NEWBRUN, E . (ed.): Etuoabove results. The children in our experimental ride and dental caries, Charles C Thomas, Springfield, III. 1972, p. 34. group after nine applications, did not fare better 9. HOROWITZ, H , S,: Caries prevention and various fluothan children in the control group who did not use ride preparations, Israel J, Dent, Med, 1974: 23: 9 1 the fluoride topically. 96. There is, however, an important variable in our 10. HOROWITZ, H . S., KAN, M . C , W . & DOYLE, J,: Restudy, namely the peculiar pattern of dental caries tained anticaries protection from topically applied among the Egyptian children, which is of the pit acidulated phosphate-fluoride. Ann. Meet. Int. Assoc. Dent. Res. 1970: Abstr. No. 607. and fissure variety. In other studies, data are gen11. HOROWITZ, H . S. & THOMPSON, M , B . : Evaluation of erally reported for pooled surfaces. Although our a stannous fluoride dentifrice for use in dental health study examined all surfaces of all teeth, the caries programs. / . Am, Dent, A.ssoc, 1967: 74: 979-986. experience was confined to the occlusal and the 12. KOCH, G.: Effect of sodium fluoride in dentifrice and buccal and palatal pits and fissures. Pits and fismouth wash on incidence of dental caries in school children. Odontol, Revy 1967: 18: 77-125. sures benefit the least from fluorides, and BACKER13. MARTHALER, T . M . : Confidence limits of clinical carDIRKS' has found that fluoridated water consumed ies. Tests with fluoride administration. Caries Res. after tooth eruption results in fewer lesions on the 1971: 5; 343. free smooth surfaces as well as on the proximal sur14. PAMIJER, J . H . , BRUDEVOLD, F . & HUNT, E, E . : A study faces of teeth. BRANSBY, FORREST & MANSBRIDGE^ of acidulated fluoride solutions. HI. The cariostatie ef-

Effect of acidulated phosphate fluoride 243 feet of repeated topical sodium fluoride applications. Arch. Oral Biol. 1963: 8; 188-195. 1 5 . STOOKY, G . K . & RATZ, S.: Chairside procedures for

using fluoride for preventing dental caries. Dent. Ctiti, North Am. 1972: 16: 681. 1 6 . WACHTEL, L . W . : Topical fluoride controversy symposium. / . Am. Soc. Prev. Dent. 1973: 3; 51-57. 1 7 . WELLOCK, W . D . & BRUDEVOLD, F . : A study of acidu-

lated fluoride solutions. IL The caries inhibiting effect of single annual topical application. Arch. Orat Biol. 1963: 8.- 1979-1982.

Address: Department oj Preventive Dentistry Faculty oj Detitistry y .;, University of Alexandria Egypt

18. WELLOCK, W . D . , MAniLi\ND, A.

& BRUDEVOLD, F . :

Caries increments, tooth diseoloration, and state of oral hygiene in children given annual applications of acid phosphate fluoride and stannous fluoride. Arch. Oral Biol. 1965: 10: 453-460. 19. ZAIIRAN, M , : Dental health of primary school children in Egypt: An incremental care program. Egypt. Dent. J. 1973: 19: 265-276. 20. ZAHRAN, M . : The pattern of dental caries in Egyptian school children: a longitudinal study. Egypt. Detit. J. . 1974: 20: 13-26. . ...

Effect of topically applied acidulated phosphate fluoride on dental caries.

Community Dent. Oral Epidemiol. 1976: 4: 240-243 (Key words: dental caries; fluorides; phosphate) Effect of topically applied acidulated phosphate fi...
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