SYSTEMIC AND TOPICAL EFFECTS ARE EXPLORED DAVID GREMBOWSKI, PH.D.; LOUIS FISET, D.D.S.; AGNES SPADAFORA, R.D.H.
© a te r fluoridation is a m ajor U.S. public h ealth program . About 54 percent of all Am er icans drink fluoridated w ater to reduce dental caries.1 Epidem i ologic studies published since 1980 indicate th a t fluoridation reduces caries by 20 percent to 40 percent in children.2 Relatively little evidence exists, however, about fluoridation’s effect on adult dental health. In th e ir 1951 study of two U.S. com m unities, Russell and Elvove reported th a t 2.5 ppm fluoride (parts of fluoride per million p arts of w ater, by weight) reduced th e num ber of decayed, m issing and filled teeth by 56 percent among adults aged 20 to 44.3 A decade later, E nglander and Wallace estim ated th a t dental caries was 40 percent to 50 percent lower in A urora (1.2 ppm F) th an in Rockford, 111. (0.1 ppm F).4 Because the optim al fluoride concentration in public w ater supplies norm ally ranges between 0.7 and 1.2 ppm F in the contiguous U nited States,5 the fluoridation benefits in the first study m ay be greater th an expected in an optim ally fluori dated community. A B ritish study in 1971 found 42 percent lower DMFT in adults in a fluoridated com m unity.6 Fluoridation’s cu rren t effects in m ost developed countries is
ABSTRACT
Oral a sse ssm e n ts co n d u cted to m ea su re c a rie s e x p e r ie n c e in a d u lts r e v e a l th a t, o n average, e a c h y e a r o f ex p o su re to flu o rid a te d w a ter r ed u c ed D FS by 0.29 su rfa ces. F lu o r i d a tio n a p p ea rs to h a v e b oth pre- a n d poste ru p tiv e b e n e fits. likely lower th a n in earlier decades because caries rates have declined. D ental caries has declined about 37 percent in U.S. children since the early 1970s.7 Although fluoridation is thought to be a m ajor cause of the decline, caries reductions as high as 60 percent in non fluoridated com m unities have also been reported.89 Most often cited for th is decline are the w idespread use of fluoride toothpastes, supplem ents, m outhrinses and topical fluoride applications in dental offices.10 Average DMFT scores among U.S. adults ages 18 to 34 years old in 1960-62 and 1971-74 show a sim ilar decline.11 W hen percent D/DFT scores (num ber of decayed tee th divided by the num ber of filled and decayed tee th x 100) in the 1971-74
H ealth and N utrition E xam ination Survey are compared w ith scores from the 1985-86 N ational In stitu te of D ental R esearch oral h ealth survey of employed adults, there is a 40 percent decline.12 The caries decline in fluoridated and non fluoridated areas could reduce the m agnitude of the expected, negative relationship between fluoridation and dental caries in adults. F luoridation’s benefits m ay be the resu lt of its pre-eruptive and post-eruptive effects.5,9 Preeruptive, or system ic, effects of fluoridation occur as fluoride is incorporated into developing enam el of perm anent teeth before perm anent dentition erupts.1013 Post-eruptive, or topical, effects occur as fluoride in drinking w ater is incorpor ated into growing crystals— either on the tooth surface (enam el m aturation) or in the subsurface (rem ineralization of previously dem ineralized enam el).,0'14’15 Much controversy exists over w hether fluoridation’s effects are m ainly system ic or topical.10 One reason for the debate is the lack of inform ation about the tim ing of fluoridation’s benefits. No study h as exam ined the effects of drinking fluoridated w ater during childhood on dental caries in adulthood. In this study, we estim ated JADA, Vol. 123, February 1992
49
th e effect of w ater fluoridation on coronal caries in adults aged 20 to 34. We also describe fluoridated w ater’s systemic and topical effects.
exposure. W ashington state employees were selected because dental claims were available to esti m ate fluoridation effects on dental dem and in later analyses. Sites were chosen to satisfy sam ple size require m ents and to obtain an equal num ber of subjects in fluori dated and non-fluoridated comm unities. Over h alf of all state employees lived in Olympia, Seattle or the Pullman/Moscow area, providing an adequate population. Olympia, the state capital, had non-fluoridated w ater. Pullm an, the location of
METHODS
The study’s population con sisted of 10,628 W ashington state employees and spousedependents aged 20 to 34 (August 1989) who lived in one of th re e sites: Olympia, Seattle and Pullman/Moscow (Idaho). The age range was chosen for th ree reasons: ™ Although caries has declined am ong 20- to 34-year-olds, caries in older age groups has TABLE 1
REDUCTION IN CORONAL DISEASE FOR EACH YEAR OF EXPOSURE Ï0 FLUORIDATED WATER DERENDENT VARIABLE
YFE COEFFICIENT (P < 0.0001)
95% CONFIDENCE INTERVAL
DFS DMFS
-0.29
(-0.39, -0.19)
-0.35
(-0.46, -0.24)
DFT DMFT
-0.08
(-0.12, -0.05)
-0.09
(-0.13, -0.06)
changed little.11 By lim iting the study to th is age group, we could observe a more homo geneous p a tte rn of caries. ■■ Insurance has positive effects on oral h ealth among people younger th a n age 35.16 Because state employees and dependents have dental insurance, lim iting the study to adults younger th a n 35 controls for variation in response effects as a resu lt of insurance. ™ A dults in this age range probably have more accurate recall of th eir residence histories th a n adults in older age groups, which should produce a more valid and reliable m easure of fluoridation 50
JADA, Vol. 123, February 1992
W ashington State University, fluoridated its w ater supply in 1956, while its neighbor, Moscow, Idaho, had naturally fluoridated w ater. Seattle fluoridated its w ater supply in 1970. A stratified random sample (n = 3,826) was performed to obtain an equal num ber of subjects in fluoridated and nonfluoridated sites. Computerassisted telephone interviews were performed by the Social and Economic Sciences Research C enter a t W ashington S tate U niversity to obtain residence histories, personal characteristics and other data. We achieved a response ra te of
85.5 percent (n = 1,875). At the end of the interview, each subject was invited to participate in a free oral assessm ent a t a convenient site in th e community, and was offered a $5 incentive to encourage participation. About 56.9 percent (n = 1,066) of the telephone respondents formed the d a ta base for this analysis. People who participated in the oral assessm ent were divided evenly betw een fluoridated and non-fluoridated sites. Partici p an ts and non-participants had sim ilar perceived oral health statu s, family incomes, house hold sizes, length of insurance coverage and percentages of fem ales. However, participants tended to be younger, better educated, w hite and live in the Pullman/Moscow area. O ral assessm ents were perform ed by five dental hygienists following protocols used in NIDR’s 1985-86 N ational Survey of Adult D ental H ealth.12 The hygienists participated in a one-week tra in in g and calibration program conducted by an NIDR stan d ard exam iner two weeks before oral assessm ents. The m ean num eric difference betw een the standard exam iner and each hygienist was less th a n 1 DMFS; reliability coefficients exceeded .98. Re calibration of exam iners in the field was not conducted because assessm ents were completed in four m onths. MEASURES
We considered the following m easures in our analyses: ™ D ental disease. Four indexes of coronal disease were calcu lated: DMFS, DFS, DMFT and DFT.12 Root caries was not m easured because of its low
TABLE 2
L — 1 — 1
L — 1 — 1
AVERAGE NUMBER OF DECAYED AN IFIL EED BY PERIOD OF FLUEIRIDATED EXPOSU REI NLIFE
c c
occurrence in th is age group and in th e U.S. employed population.1112 All indexes were based on 28 teeth (third m olars excluded). ■■ Fluoridation exposure. We m easured fluoridation effects by y ears of fluoridation exposure (YFE)—th e num ber of years someone consumed natu rally or artificially fluoridated w ater in his or h er lifetime. YFE was calculated from subjects’ residence histories and the 1985 “Fluoridation C ensus.”1 We calculated years of fluoridation exposure for specific age ranges in a lifetime to estim ate th e systemic and topical effects of fluoridated w ater. YFE was calculated for four age ranges: 0 to 5, 6 to 14, 15 to 19 and 20 to 34. Fluoridation’s systemic effect w as captured by fluoridation exposure before age 14. The distribution and validity of the YFE m easure in a children’s population were exam ined elsew here.17 The reliability and validity of YFE were assessed in this study by obtaining residence histories for a random sample of 52 respondents one year after the initial interview. YFE scores were sim ilar (r = 0.88) for the two periods. ■" Control m easures. Because several factors m ay affect an individual’s oral health, the following control variables also were collected in the telephone interview : other sources of fluoride, use of antibiotics, oral self-care, p ast use of dental services and personal charac teristics.161819 The source of fluoride group examined w hether: someone brushes twice a day (a m easure of fluoride from toothpaste); takes fluoride supplem ents; uses
AVERAGE5 DFSf
NO. OF ADULTS
No exposure in lifetime
27.9
226
Post-eruptive exposure pattern s Ages 15-34 only
22.2
266
Pre-eruptive exposure p attern s Ages 0-5 only or ages 0-14 only
20.0
40
Exposed m ost of life
15.7
63
PERIOD OF FLUORIDATION EXPOSURE IN LIFETIME*
* Each p attern consists of adults who w ere exposed to fluoridated w ater for a m ajority of years in one or more of the following periods: ages 0-5, 6-14, 15-19 and ages 20 and older. t ANO VA P
© a te r fluoridation is a m ajor U.S. public h ealth program . About 54 percent of all Am er icans drink fluoridated w ater to reduce dental caries.1 Epidem i ologic studies published since 1980 indicate th a t fluoridation reduces caries by 20 percent to 40 percent in children.2 Relatively little evidence exists, however, about fluoridation’s effect on adult dental health. In th e ir 1951 study of two U.S. com m unities, Russell and Elvove reported th a t 2.5 ppm fluoride (parts of fluoride per million p arts of w ater, by weight) reduced th e num ber of decayed, m issing and filled teeth by 56 percent among adults aged 20 to 44.3 A decade later, E nglander and Wallace estim ated th a t dental caries was 40 percent to 50 percent lower in A urora (1.2 ppm F) th an in Rockford, 111. (0.1 ppm F).4 Because the optim al fluoride concentration in public w ater supplies norm ally ranges between 0.7 and 1.2 ppm F in the contiguous U nited States,5 the fluoridation benefits in the first study m ay be greater th an expected in an optim ally fluori dated community. A B ritish study in 1971 found 42 percent lower DMFT in adults in a fluoridated com m unity.6 Fluoridation’s cu rren t effects in m ost developed countries is
ABSTRACT
Oral a sse ssm e n ts co n d u cted to m ea su re c a rie s e x p e r ie n c e in a d u lts r e v e a l th a t, o n average, e a c h y e a r o f ex p o su re to flu o rid a te d w a ter r ed u c ed D FS by 0.29 su rfa ces. F lu o r i d a tio n a p p ea rs to h a v e b oth pre- a n d poste ru p tiv e b e n e fits. likely lower th a n in earlier decades because caries rates have declined. D ental caries has declined about 37 percent in U.S. children since the early 1970s.7 Although fluoridation is thought to be a m ajor cause of the decline, caries reductions as high as 60 percent in non fluoridated com m unities have also been reported.89 Most often cited for th is decline are the w idespread use of fluoride toothpastes, supplem ents, m outhrinses and topical fluoride applications in dental offices.10 Average DMFT scores among U.S. adults ages 18 to 34 years old in 1960-62 and 1971-74 show a sim ilar decline.11 W hen percent D/DFT scores (num ber of decayed tee th divided by the num ber of filled and decayed tee th x 100) in the 1971-74
H ealth and N utrition E xam ination Survey are compared w ith scores from the 1985-86 N ational In stitu te of D ental R esearch oral h ealth survey of employed adults, there is a 40 percent decline.12 The caries decline in fluoridated and non fluoridated areas could reduce the m agnitude of the expected, negative relationship between fluoridation and dental caries in adults. F luoridation’s benefits m ay be the resu lt of its pre-eruptive and post-eruptive effects.5,9 Preeruptive, or system ic, effects of fluoridation occur as fluoride is incorporated into developing enam el of perm anent teeth before perm anent dentition erupts.1013 Post-eruptive, or topical, effects occur as fluoride in drinking w ater is incorpor ated into growing crystals— either on the tooth surface (enam el m aturation) or in the subsurface (rem ineralization of previously dem ineralized enam el).,0'14’15 Much controversy exists over w hether fluoridation’s effects are m ainly system ic or topical.10 One reason for the debate is the lack of inform ation about the tim ing of fluoridation’s benefits. No study h as exam ined the effects of drinking fluoridated w ater during childhood on dental caries in adulthood. In this study, we estim ated JADA, Vol. 123, February 1992
49
th e effect of w ater fluoridation on coronal caries in adults aged 20 to 34. We also describe fluoridated w ater’s systemic and topical effects.
exposure. W ashington state employees were selected because dental claims were available to esti m ate fluoridation effects on dental dem and in later analyses. Sites were chosen to satisfy sam ple size require m ents and to obtain an equal num ber of subjects in fluori dated and non-fluoridated comm unities. Over h alf of all state employees lived in Olympia, Seattle or the Pullman/Moscow area, providing an adequate population. Olympia, the state capital, had non-fluoridated w ater. Pullm an, the location of
METHODS
The study’s population con sisted of 10,628 W ashington state employees and spousedependents aged 20 to 34 (August 1989) who lived in one of th re e sites: Olympia, Seattle and Pullman/Moscow (Idaho). The age range was chosen for th ree reasons: ™ Although caries has declined am ong 20- to 34-year-olds, caries in older age groups has TABLE 1
REDUCTION IN CORONAL DISEASE FOR EACH YEAR OF EXPOSURE Ï0 FLUORIDATED WATER DERENDENT VARIABLE
YFE COEFFICIENT (P < 0.0001)
95% CONFIDENCE INTERVAL
DFS DMFS
-0.29
(-0.39, -0.19)
-0.35
(-0.46, -0.24)
DFT DMFT
-0.08
(-0.12, -0.05)
-0.09
(-0.13, -0.06)
changed little.11 By lim iting the study to th is age group, we could observe a more homo geneous p a tte rn of caries. ■■ Insurance has positive effects on oral h ealth among people younger th a n age 35.16 Because state employees and dependents have dental insurance, lim iting the study to adults younger th a n 35 controls for variation in response effects as a resu lt of insurance. ™ A dults in this age range probably have more accurate recall of th eir residence histories th a n adults in older age groups, which should produce a more valid and reliable m easure of fluoridation 50
JADA, Vol. 123, February 1992
W ashington State University, fluoridated its w ater supply in 1956, while its neighbor, Moscow, Idaho, had naturally fluoridated w ater. Seattle fluoridated its w ater supply in 1970. A stratified random sample (n = 3,826) was performed to obtain an equal num ber of subjects in fluoridated and nonfluoridated sites. Computerassisted telephone interviews were performed by the Social and Economic Sciences Research C enter a t W ashington S tate U niversity to obtain residence histories, personal characteristics and other data. We achieved a response ra te of
85.5 percent (n = 1,875). At the end of the interview, each subject was invited to participate in a free oral assessm ent a t a convenient site in th e community, and was offered a $5 incentive to encourage participation. About 56.9 percent (n = 1,066) of the telephone respondents formed the d a ta base for this analysis. People who participated in the oral assessm ent were divided evenly betw een fluoridated and non-fluoridated sites. Partici p an ts and non-participants had sim ilar perceived oral health statu s, family incomes, house hold sizes, length of insurance coverage and percentages of fem ales. However, participants tended to be younger, better educated, w hite and live in the Pullman/Moscow area. O ral assessm ents were perform ed by five dental hygienists following protocols used in NIDR’s 1985-86 N ational Survey of Adult D ental H ealth.12 The hygienists participated in a one-week tra in in g and calibration program conducted by an NIDR stan d ard exam iner two weeks before oral assessm ents. The m ean num eric difference betw een the standard exam iner and each hygienist was less th a n 1 DMFS; reliability coefficients exceeded .98. Re calibration of exam iners in the field was not conducted because assessm ents were completed in four m onths. MEASURES
We considered the following m easures in our analyses: ™ D ental disease. Four indexes of coronal disease were calcu lated: DMFS, DFS, DMFT and DFT.12 Root caries was not m easured because of its low
TABLE 2
L — 1 — 1
L — 1 — 1
AVERAGE NUMBER OF DECAYED AN IFIL EED BY PERIOD OF FLUEIRIDATED EXPOSU REI NLIFE
c c
occurrence in th is age group and in th e U.S. employed population.1112 All indexes were based on 28 teeth (third m olars excluded). ■■ Fluoridation exposure. We m easured fluoridation effects by y ears of fluoridation exposure (YFE)—th e num ber of years someone consumed natu rally or artificially fluoridated w ater in his or h er lifetime. YFE was calculated from subjects’ residence histories and the 1985 “Fluoridation C ensus.”1 We calculated years of fluoridation exposure for specific age ranges in a lifetime to estim ate th e systemic and topical effects of fluoridated w ater. YFE was calculated for four age ranges: 0 to 5, 6 to 14, 15 to 19 and 20 to 34. Fluoridation’s systemic effect w as captured by fluoridation exposure before age 14. The distribution and validity of the YFE m easure in a children’s population were exam ined elsew here.17 The reliability and validity of YFE were assessed in this study by obtaining residence histories for a random sample of 52 respondents one year after the initial interview. YFE scores were sim ilar (r = 0.88) for the two periods. ■" Control m easures. Because several factors m ay affect an individual’s oral health, the following control variables also were collected in the telephone interview : other sources of fluoride, use of antibiotics, oral self-care, p ast use of dental services and personal charac teristics.161819 The source of fluoride group examined w hether: someone brushes twice a day (a m easure of fluoride from toothpaste); takes fluoride supplem ents; uses
AVERAGE5 DFSf
NO. OF ADULTS
No exposure in lifetime
27.9
226
Post-eruptive exposure pattern s Ages 15-34 only
22.2
266
Pre-eruptive exposure p attern s Ages 0-5 only or ages 0-14 only
20.0
40
Exposed m ost of life
15.7
63
PERIOD OF FLUORIDATION EXPOSURE IN LIFETIME*
* Each p attern consists of adults who w ere exposed to fluoridated w ater for a m ajority of years in one or more of the following periods: ages 0-5, 6-14, 15-19 and ages 20 and older. t ANO VA P
