DF=More Caries

Dental Fluorosis = Increase in Caries
©1996 - 2020 PFPC

   There are many studies found in the international literature documenting  that an increase in dental fluorosis leads to an increase in tooth decay (caries) - the very thing it (fluoride) is proclaimed to prevent.

   While at one point it was believed that very mild and mild DF were associated with a decrease in caries in younger children, new evidence shows that these same degrees of DF actually cause an increase in both caries occurrence AND intensity as the child gets older.

A short list of 50 studies is provided below, arranged in alphabetical order.


Almerich-Silla JM, Montiel-Company JM, Ruiz-Miravet A - "Caries and dental fluorosis in a western Saharan population of refugee children" Eur J Oral Sci 116(6):512-7 (2008)

    Caries prevalence/severity rises with increasing dental fluorosis
     Table 2    Tables 3&4

Azpeitia-Valadez Mde L, Rodríguez-Frausto M, Sánchez-Hernández MA - "Prevalence of dental fluorosis in children between 6 to 15 years old" Rev Med Inst Mex Seguro Soc 46(1):67-72 (2008)

    "Dental fluorosis is a defect in the formation of the enamel by high fluoride concentrations during tooth development. It produces hypomineralization of the enamel by increasing the porosity, thus exposing the tooth to decay....The severity was mild and very mild in 90 % of cases. Tooth decay appeared in 55 % of children with fluorosis and in 43 % of children without fluorosis....The prevalence of dental fluorosis is rapidly increasing. Tooth decay affected more often children with fluorosis."

Awadia AK, Birkeland JM, Haugejorden O, Bjorvatn K - "Caries experience and caries predictors - a study of Tanzanian children consuming drinking water with different fluoride concentrations" Clin Oral Investig. 6(2):98-103 (2002)

    "Logistic regression analyses indicated that subjects in the high-F and urban Arusha municipality were at a significantly higher risk of dental caries than children in the low-F areas."


Bajaj M, Blah BC, Goyal M, Jain M, Joshi A, Ko HH, Kumar A, Lal A, Mohan ER, Nandi D, Sharma Z, Singh H, Wanyee S - "Prevalence of dental problems in school children - a study in a rural community in Haryana" Indian Journal of Community Medicine 14 (3): 106-09 (1989)

    While only 54.4% of those without fluorosis had caries, 80% of those with fluorosis had caries.


Birkeland JM, Ibrahim YE, Ghandour IA, Haugejorden O - "Severity of dental caries among 12-year-old Sudanese children with different fluoride exposure" Clin Oral Investig 9(1):46-51 (2005)

    "Children . . . drinking water with 1.0-2.0 mg fluoride/L (median = 1.8), had significantly higher caries prevalence (21% versus 8%) than in a 0.4 mg fluoride area."


Bohdal M, Gibbs NE, Simmons WK - "Nutrition survey and campaign against malnutrition in Kenya" Report to the Ministry of Health of Kenya on the WH0/FA0/UNICEF Assisted 86 Project(1968)

Budipramana ES, Hapsoro A, Irmawati ES, Kuntari S - "Dental fluorosis and caries prevalence in the fluorosis endemic area of Asembagus, Indonesia"  Int J Paediatr Dent 12(6):415-22 (2002)

    "In this study, DT (Decayed Permanent Teeth) increased with an increase in the fluoride content."


Carlsson A - "Current problems relating to the pharmacology and toxicology of fluorides" Lakartidningen 75: 1388-1392 (1978)

    "More severe degrees of enamel fluorosis are associated with an abnormally high incidence of caries... There is thus no doubt that a high degree of enamel fluorosis causes an increased tendency to caries."


Chen WS, Zhu Ling - "Surveys on fluorosis and dental caries of youngsters in high fluoride areas of Tongshan County" Stomatology 17(7):20 (2007)

    Prevalence of dental caries in fluorosis students was significantly higher than that in non-fluorosis students (12 to 15 year old

Chibole O - "Dental caries among children in high fluoride regions of Kenya" J R Soc Health 108(1):32-3 (1988)

    "When the non-fluorosis group was compared to the fluorosis group, there was a significant difference in caries experience; the fluorosis group having higher DMFT and dft... It appears that with increased severity of fluorosis there is increased susceptibility for dental caries."


Cortes DF, Ellwood RP, O'Mullane DM, Bastos JR - "Drinking water fluoride levels, dental fluorosis, and caries experience in Brazil" J Public Health Dent 56(4):226-8 (1996)

    "The children in the high-fluoride area who had dental fluorosis at or above a TF score of 3 had higher levels of dental caries than those with milder degrees of fluorosis present. This finding suggests that if fluoride intake is too high, severe enamel hypomineralization may result in increased caries risk."


Costa Sde M, Abreu MH, Vargas AM, Vasconcelos M, Ferreira e Ferreira E, Castilho LS - "Dental caries and endemic dental fluorosis in rural communities, Minas Gerais, Brazil"  Rev Bras Epidemiol 16(4):1021-8 (2013)

    "In the two younger groups, the DMFT and its decay component were higher in the group with more severe fluorosis (p < 0.001). This association was not found among adolescents and adults (p > 0.05). The association was found between the conditions more severe fluorosis and caries in individuals under 12 years."

Cunha-Cruz J, Nadanovsky P - "Dental fluorosis increases caries risk" Journal of Evidence Based Dental Practice 5:170-171 (2005)

    "The reviewed study suggests an increased risk of caries among children with fluorosis. The results are reinforced by the observed dose-response relationship: the higher the fluorosis, the higher the caries prevalence. However this was not a linear relationship; the threshold at which fluorosis appears to start increasing the risk of caries was at TF score 3."


Dobaradaran S, Ranjbar Vakil abadi D, Mahvi H, Kazemi Vakil Abadi T - "The Effect of Fluoride Drinking Water Content and Elevation above Sea on Child Dental Caries in Borazjan Villages" ISMJ 13(2):102-107 (2010)

Driscoll WS, Horowitz HS, Meyers RJ, Heifetz SB, Kingman A, Zimmerman ER - "Prevalence of dental caries and dental fluorosis in areas with negligible, optimal, and above-optimal fluoride concentrations in drinking water" J Am Dent Assoc 113(3):370 (1986)

    "Children with severe fluorosis have a significantly higher caries experience than do children with lesser degrees of fluososis."


de Lourdes Azpeitia-Valadez M, Sa¡nchez-Herna¡ndez MA, Rodriguez-Frausto M - "Risk factors for dental fluorosis in children between 6 and 15 years old" Rev Med Inst Mex Seguro Soc 47(3):265-70 (2009) 

Ekanayake L, Van Der Hoek W - "Dental caries and developmental defects of enamel in relation to fluoride levels in drinking water in an arid area of Sri Lanka" Caries Research 36: 398-404 (2002)

    "Both the caries prevalence and the mean caries experience were significantly higher in children with diffuse opacities (dental
    fluorosis) than in those without..."


Elias-Boneta AR, Psoter W, Elias-Viera AE, Jimenez P, Toro C - "Relationship between dental caries experience (DMFS) and dental fluorosis in 12-year-old Puerto Ricans" Community Dent Health 23(4):244-50 (2006)

    "....individual level fluorosis scores when dichotomized as 0-2 as the referent level to level 3-4 demonstrated a statistical significant higher DMFS with the higher fluorosis level."


Ermiş RB, Koray F, Akdeniz BG - "Dental caries and fluorosis in low- and
high-fluoride areas in Turkey" Quintessence Int 34(5):354-60 (2003) Table 4    Table 5

    Higher DMF in higher fluoride areas (HFA) than low fluoride area. Rise in DMFT with increase in DF

Forsman B - "Dental fluorosis and caries in high-fluoride districts in Sweden" Community Dent Oral Epidemiol 2(3):132-48 (1974) 

    "The highest DMFS values could be related to fluorosis Grade 3 and 4..."

Garcia-Perrez A, Irigoyen-Camacho ME, Borges-Yanez A - "Fluorosis and Dental Caries in Mexican Schoolchildren Residing in Areas with Different Water Fluoride Concentrations and Receiving Fluoridated Salt" Caries Res 47(4):299-308 (2013)

    "Fluorosis at moderate and severe levels was associated with a higher prevalence of dental caries."  

García-Pérez A, Pérez-Pérez NG, Flores-Rojas AI, Barrera-Ortega CC, González-Aragón Pineda AE, Villanueva Gutiérrez T - "Marginalization and fluorosis its relationship with dental caries in rural children in Mexico: A cross-sectional study" Community Dent Health 37(3):216-222 (2020)

Grobler SR, van Wyk CW, Kotze D - "Relationship between enamel fluoride levels, degree of fluorosis and caries experience in communities with a nearly optimal and a high fluoride level in the drinking water" Caries Research 20 (3):284-8 (1986)

    "Very interestingly and in agreement with Retief et al. [1979a] and Schamschula et al. [1979], a significant (p < 0.02) positive association was found between the caries experience (DMFS) and the enamel fluoride level of children from the high fluoride area (3.70)."


Grobler SR, Louw AJ, van Kotze TJ - "Dental fluorosis and caries experience in relation to three different drinking water fluoride levels in South Africa" Int J Paediatr Dent 11(5):372-9 (2001)

    "Significantly (P < 0.01) more children had decayed teeth in the high F area than in the other two areas. The results suggest a positive association between high F levels in the drinking water and dental caries."


Hoffman N, Schlittler RH, Sousa M, Cypriano S - "Prevalence of enamel defects and the relationship to dental caries in deciduous and permanent dentition in Indaiatuba, Sao Paulo, Brazil" Cad. Saode Publica 23(2):435-444 (2007)

    "A positive association between dental caries and enamel defects (hypoplasia, demarcated opacity and dental fluorosis) was observed for schoolchildren aged 5...The results of this study indicated that children had increased odds of dental caries when enamel defect was present, both in deciduous and permanent dentition...”

Huang KQ, Gao XQ, Li CS, Jian MX, Ren F, Wang K, Li XG, Xi HJ - "Investigation and analysis of brick-tea type dental fluorosis and dental caries among Tibetant students in Tibet Naqu" Chin J Prac Stoma 1(1):24-26 (2008)

    "The incidence of dental caries was positively correlated to the quantity of dental fluorosis (χ2MH=12.060,P0.01;OR=1.954,P0.01). There was significant linear correlation(χ2=12.715,P0.01);caries prevalence rate is in upgrade trend with aggravation of dental fluorosis (χ2=14.846,P0.01).

    With the severity of dental fluorosis, caries prevalence is rising.

    Reducing the incidence of dental fluorosis should become an important measure to prevent dental caries."


Ibrahim YE, Bjorvatn K, Birkeland JM - "Caries and dental fluorosis in a 0.25 and a 2.5 ppm fluoride area in the Sudan" Int J Paediatr Dent 7(3):161-6 (1997)

    "Analyses based on children in the 2.5 ppm area alone, showed significantly higher DMFT (Decayed, Missing, and Filled Teeth) by increased severity of dental fluorosis."


Kececi AD, Kaya BU, Guldas E, Saritekin E, Sener E - "Evaluation of den fluorosis in relation to DMFT rates in a fluorotic rural area of Turkey" Fluoride 47(2):119-132 (2014)

    "The DMFT value was significantly higher (6.59) in individuals with dental fluorosis than in those without dental fluorosis (3.18)."

Khandare AL, Validandi V, Viswanathan G, Shankar Rao G, Balakrishna N - "Role of Carbonic Anhydrase and Triiodothyronine in Dental Caries Affected Children in Fluorosis Endemic Areas" Adv Dent & Oral Health (2018)

    Caries increases with DF: Table

Kukleva MP, Kondeva VK, Isheva AV, Rimalovska SI - "Comparative study of dental caries and dental fluorosis in populations of different dental fluorosis prevalence"  Folia Med (Plovdiv) 51(3):45-52 (2009)

Liu DM,Yang GS, Guo LY, Guo L, Zhu LL - "Prevalence of dental caries and fluorosis in high-fluoride areas" J of Hebei University (3)(2003)

    Positive correlation between the prevalence of dental caries and dental fluorosis index; increase of DF intensity with age (10 to 14 year-olds); second molar more affected with caries than 1st.

Makhanu M, Opinya G, Mutave RJ - "Dental fluorosis, caries experience and snack intake of 13-15 year olds in Kenya" East Afr Med J 86(3):120-4 (2009) 

TFI 0 = DMFT of 1.30 +/- 1.03
TFI 1-4 = DMFT of 1.53 +/- 1.005
TFI 5-9 - DMFT of 1.85 +/- 1.24

    "One hundred and five individuals were found to have had a TFI score of zero with  a corresponding decayed missing and filled teeth (DMFT) for dental caries of 1.30-1.03 and 88 (52%) individuals had mild to moderate severity of dental fluorosis (TF scores 1-4) and had a corresponding mean DMFT of 1.53 +/- 1.005 for dental caries. Furthermore, 82 (48.2%) adolescents had severe degrees of dental fluorosis of TFI scores 5-9 and had a corresponding DMTF value of 1.85 +/- 1.24 for dental caries. When the prevalence of dental caries was compared among individuals with TFI scores zero (non-fluorosed teeth) with those who had fluorosed first permanent molars the Chi square test showed that there was a high statistical significance with a p-value of 0.001 (P = 0.005)."

Manji F, Kapila S - "Fluorides and fluorosis in Kenya. Part III: Fluorides, fluorosis and dental caries" Odontostomatol Trop 9(3):135-9 (1986)

    "The WHO/FAO/UNICEF study (Bohdal, Gibbs and Simmons 1968) in which some 19,000 individuals were examined, a strong positive relationship between the presence of fluorosis and the occurence of dental caries were reported, though the degree of severity of fluorosis was found not to be associated with the incidence of caries."


Mann J, Mahmoud W, Ernest M, Sgan-Cohen H, Shoshan N, Gedalia I - "Fluorosis and dental caries in 6-8-year-old children in a 5 ppm fluoride area" Community Dent Oral Epidemiol 18(2):77-9 (1990)

    "The decay rate in the permanent dentition gradually increased with increasing fluorosis severity..."


Mann J, Tibi M, Sgan-Cohen HD - "Fluorosis and caries prevalence in a community drinking above-optimal fluoridated water" Community Dent Oral Epidemiol 15(5):293-5 (1987)

    "A statistically significant positive association was found between caries prevalence and fluorosis; the more caries experienced, the more severe the fluorosis level. Boys experienced significantly higher fluorosis levels than girls."


Molina-Frechero N, Pierdant-Rodríguez AI, Oropeza-Oropeza A, Bologna-Molina R - "Fluorosis and dental caries: an assessment of risk factors in Mexican children" Rev Invest Clin. 2012  64(1):67-73 (2012)
(11 year old children)

    “Children with fluorosis of moderate to severe levels had a higher proportion of caries, which is due to advancing demineralisation and greater inclination for lesions.”

Nanayakkara D, et al. - "Dental fluorosis and caries incidence in rural children residing in a high fluoride area in the dry zone of Sri Lanka" Ceylon J Med Sci 42:13-17 (1999)

    "The prevalence of caries increased as the degree of fluorosis increased. The mean DMFT was 0.43 in children showing no fluorosis but increased up to 1.65 in children showing a fluorosis score of 3."

                                         Table 2


Olsson B - "Dental findings in high-fluoride areas in Ethiopia" Community Dent Oral Epidemiol 7(1):51-6 (1979)

    "Teeth with moderate and severe fluorosis more frequently had dental caries than teeth with no or very mild and mild fluorosis.... Gingivitis was seen in 97% of the children..."


Pontigo-Loyola AP, Medina-Solis CE, Borges-Yañez SA, Patiño-Marín N, Islas-Márquez A, Maupome G - "Prevalence and severity of dental caries in adolescents aged 12 and 15 living in communities with various fluoride concentrations" J Public Health Dent 67(1):8-13 (2007)

    "Finally, an association of severity of dental fluorosis and caries severity was observed. While fluorosis was very common, it was often mild or very mild...The results showed that children with dental fluorosis have higher severity of caries (DMFT ≥ 4)."

    "When we compared high-severity caries group (DMFT ≥ 4 as cutoff point), we observed higher caries severity in children with fluorosis (9.6 percent in very mild/mild, and 10.6 percent in moderate/severe) than children without fluorosis (7.8 percent). Additionally, compared only DMFT=0 versus DMFT ≥ 4 similar results were observed; prevalence of DMFT ≥ 4 in fluorosis-free children was 13.5, while 15.5 and 17.1 was observed in children with very mild/mild and moderate/severe fluorosis."


Ramezani GH, Valaei N, Eikani H- "Prevalence of DMFT and fluorosis in the students of Dayer city (Iran)" J Indian Soc Pedod Prev Dent 22(2):49-53 (2004)

Rise in DMFT with increasing rate of dental fluorosis.

Retief DH, Bradley EL, Barbakow FH, Friedman M, Van der Merwe EHM, Bischoff JI - "Relationships among fluoride concentration in enamel, degree of fluorosis and caries incidence in a community residing in a high fluoride area" Journal of Oral Pathology 8:224-236 (1979)

Sharma P, Bhardwaj AK, Singh M, et al. - "Does fluorosis affect the intelligence profile of children? A cross sectional analysis of school children of district Una, Himachal Pradesh, India" International Journal of Community Medicine and Public Health 5(3):1047 (2018)

    “Risk of dental caries and DAI were more prevalent in areas with high fluoride level in water." (>0.5 ppm)


Shekar C, Cheluvaiah MB, Namile D - "Prevalence of dental caries and dental fluorosis among 12 and 15 years old school children in relation to fluoride concentration in drinking water in an endemic fluoride belt of Andhra Pradesh" Indian J Public Health 56(2):122-8 (2012)

Tuli A, Rehani U, Aggrawal A - "Caries experience evidenced in children having dental fluorosis" International Journal of Clinical Pediatric Dentistry 2(2): 25 (2009) 

    "The DMFT increased as the severity of fluorosis increased from grade 1 to grade 2". (Dean Index: “questionable” to “mild”)


Varela-González G, García-Pérez A, Huizar-Alvarez R, Irigoyen-Camacho M, Espinoza-Jaramillo M - "Fluorosis and Dental Caries in the Hydrogeological Environments of Southeastern Communities in the State of Morelos, Mexico" Journal of Environmental Protection 4(9):994-1001 (2013)
doi: 10.4236/jep.2013.49115.
(DF severity increases with age/More DF and more caries found together w/increasing F- in water)

Table 1


Wang B, Fan Q, Zhe PP, Wang W, Chu W, Ji JJ - "Surveys on Fluorosis and Dental Caries of Middle Aged People in High Fluoride Areas of Zhaotong
County, Yunnan" Journal of Kunming Medical University 31(6) (2010)  

    Moderate and severe fluorosis cause more caries and caries severity. More caries in DF than non-fluorosis adults.


Wondwossen F, Astrom AN, Bjorvatn K, Bardsen A - "The relationship between dental caries and dental fluorosis in areas with moderate- and high-fluoride drinking water in Ethiopia" Community Dent Oral Epidemiol 32(5):337-44 (2004)

    "Independent of the fluoride concentration in drinking water, caries prevalence increased consistently with increasing severity of dental fluorosis in the second molars, first molars, premolars and canines."


Wozniak K - "Developmental abnormalities of mineralization in populations with varying exposure to fluorine compounds"  Ann Acad Med Stetin 46:305-15 (2000)

  • "Children with developmental defects of dental enamel had a significantly higher incidence of caries and elevated mean DMF, as compared to children without any abnormalities of mineralization."

Zhang R, Cheng L, Zhang T, Xu T, Li M, Yin W, Jiang Q, Yang Y, Hu T- "Brick tea consumption is a risk factor for dental caries and dental fluorosis among 12-year-old Tibetan children in Ganzi" Environ Geochem Health 41(3):1405-1417 (2019)

    "Mother's regular consumption of brick tea was a risk factor for both dental fluorosis and dental caries among children. Reducing mother's brick tea consumption during pregnancy and lactation may improve oral health status of their children."



Teotia SPS, Teotia M - "Dental Caries: A Disorder of High Fluoride and Low Dietary Calcium Interactions (30 Years of Personal Experience)" Fluoride 27: 59-66 (1994)

    "Our findings indicate that dental caries was caused by high fluoride and low dietary calcium intakes, separately and through their interactions. Dental caries was most severe and complex in calcium-deficient children exposed to high intakes of endemic fluoride in drinking water."


In Vitro:

Waidyasekera PG, Nikaido T, Weerasinghe DD, Wettasinghe KA, Tagami J - "Caries susceptibility of human fluorosed enamel and dentine" J Dent 35
(4):343-9 (2007)

    "...mild and moderately fluorosed dentine was significantly caries susceptible in vitro."

Waidyasekera K, Nikaido T, Weerasinghe D, Watanabe A, Ichinose S,
Tay F, Tagami J - "Why does fluorosed dentine show a higher susceptibility for caries: an  ultra-morphological explanation" J Med Dent Sci 57(1):17-23 (2010)

Luo LY, Wang Y, Li H, Zheng H, Gao SJ - "Study on remineralization of human fluorosed teeth in vitro" West China Journal of Stomatology 
(01):33 (2009)

  • "...major demineralization was under the surface of the enamel, which was similar to the early natural enamel caries.”

See also:

Cheono D, Johansen E - "Caries in rats receiving systemically administrated fluoride during tooth development"/ JADR Meeting 1971 Abstract No 783,
p. 248

NOTE: The statement that fluoride reduces caries by being incorporated into the enamel, thus "making the tooth stronger", is entirely wrong.

The fluoride content of the enamel is increased with increasing severity of fluorosis (Richards et al, 1989).  

The more severe the fluorosis - the more caries can be expected.

Richards A, Fejerskov O, Baelum V - "Enamel fluoride in relation to severity of human dental fluorosis" Adv Dent Res 3(2):147-53 (1989)


Other recent studies involving topical applications:

Cunha-Cruz J - "Teacher-supervised toothbrushing with fluoride has little effect on dental caries prevention" J Evid Based Dent Pract 5(4):202-4 (2005)

Bretz W - "No benefit from regular 6-month fluoride gel applications in low-risk caries individuals" J Evid Based Dent Pract 6(2):183-4 (2006)

Kececi AD, Kaya BU, Guldas E, Saritekin E, Sener E - "Evaluation of dental fluorosis in relation to DMFT rates in a fluorotic rural area of Turkey" Fluoride 47(2):119-132 (2014)


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