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Microbiome Associated with Severe Caries in Canadian First Nations Children


It was a great pleasure for me to host Dr. Bob Schroth, Assistant Professor in the Department of Oral Biology in the Faculty of Dentistry; and the Department of Pediatrics & Child Health in the Faculty of Medicine at the University of Manitoba. He joined me from Winnipeg to speak about an article he recently published on the higher degree of severe early childhood caries that young indigenous children suffer from. 

The title of the article is: Microbiome Associated with Severe Caries in Canadian First Nations Children, published in the Journal of Dental Research (2017).

I hope you enjoy the interview. Please share your feedback, suggestions, and questions through oasisdiscussions@cda-adc.ca

Until next time!

Chiraz Guessaier, CDA Oasis Manager


  • Young Indigenous children in North America suffer from a higher degree of severe early childhood caries (S-ECC) than the general population, leading to speculation that the etiology and characteristics of the disease may be distinct in this population.
  • To address this knowledge gap, the authors conducted the first microbiome analysis of an Indigenous population using modern molecular techniques. The authors investigated the caries-associated microbiome among Canadian First Nations children with S-ECC. Thirty First Nations children <72 mo of age with S-ECC and 20 caries-free children were recruited in Winnipeg, Canada.
  • Parents or caregivers completed a questionnaire on general and dental health, diet, and demographics. The plaque microbiome was investigated by sequencing the 16S rRNA gene. Sequences were clustered into operational taxonomic units and taxonomy assigned via the Human Oral Microbiome Database, then analyzed at the community level with alpha and beta diversity measures.
  • Compared with those who were caries free, children with S-ECC came from households with lower income; they were more likely to live in First Nations communities and were more likely to be bottle-fed; and they were weaned from the bottle at a later age. The microbial communities of the S-ECC and caries-free groups did not differ in terms of species richness or phylogenetic diversity.
  • Beta diversity analysis showed that the samples significantly clustered into groups based on caries status. Twenty-eight species-level operational taxonomic units were significantly different between the groups, including Veillonella HOT 780 and Porphyromonas HOT 284, which were 4.6- and 9-fold higher, respectively, in the S-ECC group, and Streptococcus gordonii and Streptococcus sanguinis, which were 5- and 2-fold higher, respectively, in the caries-free group. Extremely high levels of Streptococcus mutans were detected in the S-ECC group.
  • Overall, First Nations children with S-ECC have a significantly different plaque microbiome than their caries-free counterparts, with the S-ECC group containing higher levels of known cariogenic organisms.

Full Interview (16.56″)




  1. Larry Levin January 24, 2018

    Great interview and very interesting with tremendous potential.
    I wonder if Dr. Schroth feels the the same would hold true for non-indigenous children with S–ECC.
    In other words is there any part of this study that really looks at an indigenous S-ECC as opposed to any child with a similar causative background.
    My takeaway is that in a mouth with undisturbed abundant plaque, coupled with the other factors discussed, not only is the quantum increased but also the ratio of harmful bacteria.
    It seems to me that this would be true regardless of whether the child is indigenous or not.
    (We also see this in periodontal disease in deeper pockets with a change in microbiome and the proliferation of spirochetes and other harmful bacteria.)
    My concern is that it makes S-ECC sound like more of an indigenous microbiome problem, rather than microbiome problem that can affect any child with a similar background.
    Thanks again.
    Larry Levin

    1. Robert Schroth January 25, 2018

      Hello Dr. Levin,
      Thanks for the feedback and questions.
      While there have been recent studies on the microbiome of children affected with S-ECC, none of them were specific to Indigenous children. This pilot study originated from the QUEST microbiology working group. Chiraz will be profiling other research from the QUEST group in the coming weeks/months. The reality is that Indigenous children in North America, including First Nations and Inuit children in Canada, often have a higher disease burden (i.e. more aggressive decay patterns). Our intent is not to stigmatize First Nations children, but to begin to understand why the severity of S-ECC is higher. Our colleagues at UCLA, who have performed thousands of microbiome analyses on children, have never seen levels of strep mutans this high. We recognize that diets have a key role to play, but we are now realizing that the microbiome along with enamel defects may also have a critical role. Then layer on diet (often restricted by socioeconomics), access to care challenges and family finances, and this then heightens caries-risk. There is more research to be done and this is just the beginning. Future studies could look at the microbiome in different populations of Canadian children.

      Kind regards,

  2. Isabella Botha January 25, 2018

    Dear Dr Schroth,

    I work mostly in Aboriginal Communities in Northern Manitoba. Some factors that might contribute to the high caries incidence: some of these communities have no fluoride in their drinking water; the parents themselves have poor oral hygiene (many pregnant women do not show up for dental care during their pregnancies and only visit the dental clinic when they experience tooth ache after the birth of the baby.

    Lack of a reliable babysitter is usually given as a reason for not visiting a dental clinic, Socio-economic problems is a big contributing factor. Alcohol an drug abuse in the communities are the norm. Cannabis is smoked by a very high percentage of my patients. Fresh food is very expensive in these communities while pasta, chips, pop and candy are relatively inexpensive. Milk formula is very expensive. Babies and Toddlers are often given sugary drinks in their bottles in stead of milk or water. They are also put to bed with these sugary drinks.

    Most parents only bring their babies in for their first visit by the age of 24 months. By that time the teeth are already badly decayed. Many parents do not brush their babies’ teeth because of ignorance and because it is not on their priority list: Use drugs, sleep in late, neglect their children. There are parents who take good care of their children and brush their teeth regularly. These children’s teeth usually have less decay.

    All dental clinics in Northern Manitoba have a fairly big percentage of “no-shows” and we often have to double book or keep a list of short notice patients. Parents often threaten to take their children to the nursing station or dental clinic for a “needle” as punishment for bad behaviour, and fear of dental treatment is a big factor for irregular dental visits. Many people come for dental treatment only when they experience dental pain. If their teeth don’t bother them they think they don’t need to visit a dentist. Education in proper dental care is an ongoing effort.

  3. Robert Schroth January 28, 2018

    Thanks, Isabella.
    ECC is definitely impacted by the determinants of health, particularly the social determinants of health.
    This pilot study was strictly focused on the microbiome, but other studies have definitely looked at other factors, including access to care.
    There is now some exciting work beginning where researchers are partnering with First Nations and other Indigenous communities to work together to promote early childhood oral health, raise awareness of dental health among parents and communities, and implementing community developed strategies to address young children’s oral health.
    Kind regards,


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