Early childhood caries: modifiable risk factors


Early childhood caries is a significant global health problem and is increasing rapidly in low- and middle-income countries. The main risk factors is exposure to sugar but there are a factors that can potentially mitigate this risk such as dietary patterns, oral hygiene practices and exposure to fluoride.

The aim of this review was to assess the evidence pertaining to the effect of modifiable risk factors on early childhood caries (ECC). The review was commissioned by The World Health Organization (WHO).


A number of specific questions related to the main question were prioritised by a WHO expert panel. Searches were conducted in the Medline/PubMed, Embase, CINHAL, Cochrane Library, U.S. National Library and the WHO’s International Clinical Trials Registry Platform.  Relevant randomised controlled trials (RCTs) other intervention studies, and observational studies (including cohort, case-control, ecologic, and cross-sectional studies) were considered.

For each of the questions the highest level of evidence was retrieved and synthesised as appropriate. Individual study quality was assessed using the Cochrane risk of bias tool for RCTs and the ROBINS-I for nonrandomized trials and all other study designs.  GRADE was used to assess the overall body of evidence.


133 studies reported in 137 papers were included.

  • Does breastfeeding beyond 1 y increase the risk of ECC as compared with breastfeeding until <1y of age?
    • 21 studies (1 prospective cohort 1 case-control, 19 cross-sectional).
    • No significant difference in caries severity at 5 years of age with breast feeding up to 1 year [Moderate certainty evidence].
    • No significant increase in ECC. [Low certainty evidence].
  • Does breastfeeding beyond 1y increase the risk of ECC as compared with cow’s (or similar) milk consumption as the main milk source from 1y of age?
    • No studies identified.
  • Does breastfeeding beyond 2yrs increase the risk of ECC as compared with breastfeeding until <2 y of age?
    • 8 studies; 2 cohort studies, 1 case-control study, and 5 cross-sectional studies.
    • Low certainty evidence of an increased risk of caries risk when breastfeeding beyond 2 years.
  • Does breastfeeding beyond 2yrs increase the risk of ECC as compared with cow’s (or similar) milk consumption as main milk source from 2yrs of age?
    • No studies identified.
  • Does consumption of liquids that contain free sugars from an infant feeding bottle increase the risk of ECC?
    • 31 studies, 3 cohort studies, 2 case-control studies, and 25 cross-sectional studies.
    • Significant increased risk of severe ECC with use of bottles containing fruit juices or soft drinks at 12 months of age (RR = 1.41; 95%CI, 1.08 to 1.86) [Low certainty evidence].
  • Does consumption of complementary drinks that contain free sugars increase the risk of ECC?
    • 8 studies (6 cohorts, 2 cross-sectional)
    • Available data suggesting an increased risk of ECC from consumption of sugars-containing drinks is of very low certainty.
  • Does consumption of complementary foods to which free sugars have been added increase the risk of ECC?
    • 1 cohort study showed a relative risk of severe ECC of 1.43 (95% CI, 1.08 to 1.89) with consumption of items with a high density of added sugars versus no consumption [low certainty evidence].
  • Does oral hygiene provided by a parent/carer reduce the risk of ECC?
    • 21 studies, 2 cohort studies, 1 quasi-experimental study, and 17 cross- sectional)
    • Evidence suggests little effect of oral hygiene provided by a parent or caregiver on ECC risk [Very low certainty evidence].
  • Is oral health education for caregivers’ effective for preventing ECC?
    • 14 studies 6 RCTs, 2 cohort studies, and 6 quasi- experimental studies
    • A random effect meta-analysis of 3 RCTs found: –
      • Children of caregivers who received oral health education had a reduced risk of ECC as compared with those of caregivers who had never received oral health education; odds ratio = 0.39 (95%CI; 0.19 to 0.79) [Moderate certainty evidence].
      • A non-significant trend to a lower mean (SD) dmft; standardized mean difference= –0.15 (95%CI; –0.34 to 0.05) [Moderate certainty evidence].
    • Does an optimum concentration of fluoride in water reduce the risk of ECC?
    • 32 studies, 13 cohort studies, 15 cross- sectional studies, and 4 ecologic studies.
      • Pooled data (4 studies) showed evidence of a significant protective moderate-sized effect of exposure to fluoridated water (mean difference between fluoridated and non-fluoridated, –1.25 (95%CI; –2.14 to –0.36) [Moderate certainty evidence].
    • Does consumption of fluoridated milk reduce the risk of ECC?
      • 3 studies, 1 quasi- experimental and 2 cross-sectional studies.
      • Low certainty evidence of a protective effect from fluoridated milk.
    • Does salt fluoridation reduce the risk of ECC?
      • 4 studies 1 RCT, 1 cohort study, and 2 quasi-experimental studies.
      • Data from the RCT showed a lower level of cavitation in the test group. The percentage free of caries into dentine was 25.0% in the test group and 16.8% in the control but this was not significant RR= 0.88(95%CI; 0.79 -1.01) [Moderate certainty evidence].


The authors concluded: –

The best available evidence indicates that breastfeeding up to 2 y of age does not increase ECC risk. Providing access to fluoridated water and educating caregivers are justified approaches to ECC prevention. Limiting sugars in bottles and complementary foods should be part of this education.


The authors have used a good methodological approach for this review and have identified evidence to address 10 of the 12 questions that have been posed. However, a number of systematic reviews have already been published which have addressed the same of very similar questions in the recent past. For example reviews of breastfeeding, water, milk and salt fluoridation (see other references). So, while this publication has involved a significant amout of work and helpfully summarises the evidence on the twelve questions addressed it also highlights a duplication of effort that has become all to common in dental systematic reviews.  In addition when these these multiple reviews also continue to highlight important biases in the quality of the primary research that need to be addressed this  should indicate a pressing need for a much greater focus on improving dentistry primary research base to address the evidence gaps that  reviews continue to higlight.


Primary Paper

Moynihan P, Tanner LM, Holmes RD, Hillier-Brown F, Mashayekhi A, Kelly SAM, Craig D. Systematic Review of Evidence Pertaining to Factors That Modify Risk of Early Childhood Caries. JDR Clin Trans Res. 2019 Jul;4(3):202-216. doi:10.1177/2380084418824262. Epub 2019 Feb 14. PubMed PMID: 30931717.

Review protocol on PROSPERO

Other references

Dental Elf – 25th Sept 2017

Breastfeeding and caries: New review supports earlier findings

Dental Elf – Early Childhood caries blogs


Dental Elf – 7th Sep 2017

Fluoridated milk: low quality evidence of benefit

Dental Elf – 12h May 2017

Breast feeding duration and caries risk

Dental Elf – 19th Jun 2015

Water fluoridation effective at reducing caries

Dental Elf – 7th Sep 2015

Fluoridated milk: low quality evidence of benefit




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