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03-10-2011 | Article

Microbiota and diet differentiate young children with caries relapse

Abstract

Free abstract

MedWire News: The microbiota of children treated for early childhood caries (ECC) who relapse is different from that of children who experience no later progression of caries, research shows.

Children who remained free of new caries during the year after therapy tended to show a reduction in Streptococcus mutans after treatment compared with those whose caries progressed, the US investigators report.

In addition to variation in the microbiota of children who experienced progression and those who did not, the children's diet clearly influenced their likelihood of treatment success.

Anne Tanner (Forsyth Institute, Cambridge, Massachusetts, USA) and colleagues comment: "We propose that severe ECC is a complex infection, with the possibility that the microbiota and diet may have different degrees of influence in different children."

The findings are based on plaque samples taken from 85 medically healthy children, aged 2 to 6 years, of whom 53 had severe ECCs and 32 were caries free.

The children's plaque was sampled at baseline and again at six and 12 months after restorative treatment and extraction.

Children who developed new caries by the 6 or 12 month assessment were no longer followed up.

Tanner and colleagues analyzed DNA purified from the plaque samples with microarrays to 300 bacterial taxa using the Human Oral Microbe Identification Microarray (HOMIM) assay, and bacteria-specific polymerase chain reaction (PCR).

The microarray results revealed that plaque samples from severe ECC children were more likely to test positive for Slackia exigua, S. parasanguinas I and II, Prevotella melaninogenica, and Prevotella Cluster IV bacteria.

Children who showed evidence of Prevotella Cluster IV bacteria, Prevotella nigrescens, and certain Capnocytophaga taxa at baseline were significantly more likely to develop new lesions during follow-up, although the difference did not reach statistical significance.

Specific PCR analyses identified the presence of the following taxa individually as being linked with severe ECC: S. mutans, S. sobrinus, Bifidobacteriaceae, and Scardovia wiggsiae. The combined presence of S. mutans with S. sobrinus, S. mutans with Bifidobacteriaceae, and S. mutans with S. wiggsiae were also associated with severe ECC, the researchers report.

Aside from the taxa within their plaques, children with severe ECC were more likely to consume putative cariogenic foods, and eat and drink more frequently, than children free from caries at baseline.

Discussing their results, Tanner et al note that the association of S. exigua with severe ECC was "a new finding, suggesting that the species may be a risk factor for this infection."

Multivariate modeling identified two different ECC groups that the authors described as severe.

"Both severe ECC groups had poor oral hygiene and a similar level of S. mutans infection, but one group ate more cariogenic foods while the other was characterized by a multispecies complex including Bifidobacteriaceae and S. sobrinus," they write.

By Josephine McCoan