What do systematic reviews say?

Fluoride concentration relative to the acceptable range (electrometric ion-selective electrode measurement; acceptable range mostly 0.6-0.8 ppmF) vs None (descriptive proportion meta-analysis)

In the Northeast Brazilian region, a pooled 79.7% of water samples had fluoride below the acceptable range; ungraded.

• External control of fluoridation in the public water supplies of Brazilian cities as a strategy against caries: a… 2021 All outcomes

  Public water supply / water treatment stations in Brazilian cities (external control of artificial fluoridation) · Region: Northeast Brazil
  Prevalence 79.7
  Studies not reported
  GRADE not reported
• External control of fluoridation in the public water supplies of Brazilian cities as a strategy against caries: a… 2021 All outcomes

  Public water supply / water treatment stations in Brazilian cities (external control of artificial fluoridation) · Region: Southeast Brazil
  Prevalence 24.6
  Studies not reported
  GRADE not reported

Intervention not reported

• External control of fluoridation in the public water supplies of Brazilian cities as a strategy against caries: a… 2021 All outcomes
  Prevalence 45.0 [26.1, 64.7]
  12 studies
  GRADE not reported

Intervention not reported

• External control of fluoridation in the public water supplies of Brazilian cities as a strategy against caries: a… 2021 All outcomes

  Region: South Brazil
  Prevalence 32.4 [7.1, 65.3]
  Studies not reported
  GRADE not reported