The relationship between childhood body weight and dental caries experience: an umbrella systematic review protocol
Carson et al. Systematic Reviews
The relationship between childhood body weight and dental caries experience: an umbrella systematic review protocol
Susan J. Carson 0 1
Lamis Abuhaloob 1
Derek Richards 0 1 2
Mark P. Hector 1
Ruth Freeman 0 1
0 Dental Public Health , NHS Tayside, Dundee, Scotland
1 Dental Health Services Research Unit, School of Dentistry, University of Dundee , Park Place, Dundee DD1 4HR, Scotland
2 Dental Public Health , NHS Forth Valley, Stirling, Scotland
Background: Obesity and dental caries are global public health problems which can impact in childhood and throughout the life course. In simple terms, childhood dental caries and body weight are linked via the common risk factor of diet. An association between dental caries and obesity has been described in a number of studies and reviews. However, similarly, a relationship has also been noted between low body weight and caries experience in children. This protocol will provide the framework for an umbrella review to address the following question: Does the available evidence support a relationship between dental caries experience and body weight in the child population? Methods: This review protocol outlines the process to carry out an umbrella systematic review which will synthesise previous reviews of childhood dental caries experience and body weight. An umbrella review methodology will be used to examine the methodological and reporting quality of existing reviews. Discussion: The final umbrella review aims to aggregate the available evidence in order to provide a summary for policymakers and to inform healthcare interventions. Systematic review registration: PROSPERO CRD42016047304
Dental public health; Child oral health; Dental caries; Body weight and umbrella systematic review
An increase in the number of individuals who are
overweight or obese is proving to be one of the most
challenging public health problems of the modern era [
Research suggests that there is a positive relationship
between childhood obesity and obesity in adulthood
]. Dental caries (decay) in children is consistently
found to be one of the most common non-communicable
diseases worldwide [
]. The Global Burden of Disease
(GBD) 2010 Study found untreated dental caries in
permanent teeth to be the most prevalent oral condition
globally with around 35% of the population affected [
consumption of excess free sugar has been implicated in
the development of a number of non-communicable and
chronic conditions such as obesity, type 2 diabetes and
dental caries [
]. In simple terms, dental caries and body
weight are linked via the shared risk factor of diet [
free sugars are a common risk factor for both dental caries
and body weight, what then is the relationship between
dental caries and body weight?
An association between these two conditions have been
reported in a number of individual studies; however, the
results and methodologies are mixed and provide
contradictory evidence [
]. The relationship between dental caries
and body weight in children and adolescents has been
looked at in three systematic reviews [
reviews suggested that a relationship could exist, but that it is
far from simplistic. The Hooley et al. review also found
evidence which suggests that a converse, dental caries and low
body weight relationship may exist [
]. In 2015, Public
Health England released an evidence summary entitled
“The relationship between dental caries and obesity in
]. This made use of published literature and
routine public health monitoring data to review and
summarise what is known about the relationship between
dental caries and obesity in individuals and populations.
The review also found that much of the available evidence
was in relation to the obesity and caries relationship in
childhood. The results of this evidence summary describe
four systematic reviews, the three detailed previously
] and an additional paper by Kantovitz et al
]. Again, an equivocal relationship between dental
caries and body weight was found. The authors made
use of the recently available ROBIS tool which found
several of the reviews to be at high risk of bias [
This wealth of varying quality and contradictory
evidence suggests the need for an umbrella review to bring
together the accessible evidence to permit an
understanding of the relationship between dental caries and
body weight in children in order to inform policy and
potential healthcare intervention. It is expected that this
work will be significant in defining the degree of
adequacy in the methodological quality and reporting of
systematic reviews of observational studies which look at
the association between body weight and childhood
The aim of this umbrella review is to summarise what is
already known about the relationship between body
weight and childhood dental caries experience in order
to make recommendations for policy and to inform
healthcare interventions which adopt the Common Risk
Factor Approach (CRFA) [
What is the relationship between dental caries
experience and body weight in children?
This protocol has regarded for the Preferred Reporting
Items for Systematic review and Meta-Analysis Protocols
(PRISMA-P) checklist [
] and is registered with the
PROSPERO database for systematic reviews [
completed PRISMA-P checklist for the protocol is attached as
an additional file (see Additional file 1). The protocol has
been revised by the authors; all updates and amendments
can be found within the PROSPERO record.
In 2007, Moher et al. reported that “whilst systematic
reviews are now produced in large numbers, the quality
of their reporting is inconsistent” [
]. Given that a
number of systematic reviews have been published on
this topic, we will adopt a review of reviews or umbrella
review method as described in Grand and Booth’s
typology of reviews [
]. Umbrella review is the term
applied to systematic reviews that draw together evidence
from a series of other systematic reviews and meta-analyses
]. They are a means of reporting evidence other than
that derived from randomised controlled trials and have
been proposed as a way to provide a clear picture of a
broad healthcare topic area [
]. The review will have
regarded for the umbrella review methodology as outlined
by Aromataris et al. in 2015 [
This umbrella systematic review will specifically look
at the quality of systematic reviews which have
previously been carried out. It will appraise both the
methodological and reporting characteristics of multiple
reviews making use two available quality assessment
tools: AMSTAR and PRISMA [
]. In 2014, Pieper
et al. tested the use of AMSTAR tool in appraising
systematic reviews of non-randomised studies . They
found the tool to be reliable with only items 6 to 9
requiring further discussion between the reviewers. It was
felt that this mainly arose due to the lack of standards
for non-randomised studies when compared with
randomised control trials, rather than an inherent problem
with the questions themselves [
]. This review will
focus on a quality assessment of the methodology and
reporting of the reviews themselves, rather than the
Types of participants
Participants will be children defined as those under
18 years of age.
Phenomena of interest
The phenomena of interest in terms of the
relationship with dental caries experience are body weight.
Body weight as measured by weight, BMI, waist
circumference or any other recognised methods will be
Outcomes for the primary, mixed and secondary
dentition will be considered for inclusion. Any measure of
dental caries including, but not limited to, DMFT
(Decayed, Missing and Filled Teeth), DMFS (Decayed,
Missing and Filled Surfaces), and caries incidence will be
No limitations will be made in relation to cultural factors
such as geographic location, specific racial or gender-based
Types of studies
Studies will be systematic reviews or meta-analyses of
observational studies in humans. Systematic reviews or
meta-analyses which include cross-sectional, case series,
case-control, cohort studies, or aetiology studies using
data from an existing database will be included. All
systematic reviews which look at the association between
dental caries and body weight in children in the same
individuals and populations will be considered.
A summary of the main study inclusion and exclusion
criteria are provided in Table 1.
Only full articles available in English will be reviewed. A
list of possibly relevant titles in other languages will be
provided as an appendix. As the availability and
methodology of systematic reviews has increased since 1990
], it has been decided a priori to limit the search to
systematic reviews from 1990 onwards.
The following electronic databases will be searched:
MEDLINE, CINAHL, EMBASE, PsycINFO and Scopus.
Additional systematic review databases, the JBI Database
of Systematic Reviews and Implementation Reports, the
Cochrane Register of Systematic Reviews and
PROSPERO will also be searched. Manual screening of the
reference lists of retrieved articles will also be carried out.
A search for both black and unpublished grey literature
will include databases which contain published reports
from government and non-government organisations as
well as additional material which have otherwise not
been published [
]. The Open Grey system for
information on grey literature, the Agency for Healthcare
Research and Quality database and the National Health
and Medical Research Council database and Google
Scholar will be used to aid in this search. The search
process will be tailored to the specific host site.
We will conduct a search of electronic databases using
MeSH terms and selected free-text terms (including
those retrieved from published reviews which can be
found in Table 2) as well as terms for systematic reviews
and meta-analyses (Table 3). A search strategy has been
drafted in collaboration with a Medical Librarian and
has been trialled in MEDLINE; Additional file 2 shows
this in more detail. This included planned limits so that
the search could be repeated.
The initial search will be carried out by the lead reviewer.
Screening of titles and abstracts will be carried out
independently by two reviewers. Any disagreement will be
resolved by discussion and, if necessary, by a third reviewer. If
a decision on inclusion cannot to be made based on the
title or abstract, the full text will be considered and any
reasons for exclusion which are based on this will be provided.
Data extraction and management
Data from published reviews to be included will be
abstracted into Endnote X7. Duplicates of individual
systematic reviews will be deleted. A data extraction form
has been designed to reflect the reporting standards for
umbrella systematic reviews as outlined in the JBI
methodology. Two reviewers will independently review the
data, and any unresolved discrepancies will be settled
through discussion with the review group. This tool is
formed of the existing AMSTAR tool with additional
reporting items from the PRISMA tool included [
As this tool contains items derived from existing
guidelines, it is believed the validity of the tool should be
]. The article flow and number of
included studies will be described in a PRISMA flow
diagram in the final report [
Assessment of methodological quality
The AMSTAR [
] checklist will be used to assess the
methodological quality of systematic reviews and
metaanalyses that are eligible for inclusion. The
methodological quality assessment will be carried out by two of
the review team independently. Any unresolved
discrepancies will be resolved through discussion and consensus
agreement within the review group. The methodological
quality of each retrieved review will be graded as good,
fair or poor using the guidance criteria within the
AMSTAR tool [
Types of study
Period of study
Types of participants
phenomena of interest
Systematic reviews and meta-analyses
Any systematic review from 1990 to 2017
Children as defined by < 18 years
Dental caries experience (as measured
by any means)
Body weight as measured by BMI, or
Full articles in English
All other types of study
Systematic review prior to 1990
Studies where children are not the population of interest
Studies where dental caries is not the outcome of interest,
i.e. other dental problems
Studies which do not look at body weight in relation to
dental caries experience
Relevant articles in languages other than English
Assessment of reporting bias
A risk of bias assessment is included within the AMSTAR
]. If more than 10 studies with the same outcome
measure are available for review, a funnel plot will be used
to explore the potential of publication bias. Selective
reporting within systematic reviews or of review findings will be
recorded. This will be assessed through the comparison of
actual reported outcomes with those stated within the
The PRISMA checklist will be used to assess the
reporting quality of systematic reviews and meta-analyses that
are eligible for inclusion [
]. The findings and
conclusions from existing reviews will be presented in narrative
form including tables and figures to aid in data
presentation where appropriate. The limitations of each review
will be reported and will include any confounders and
potential moderating or mediating factors. It is
anticipated that statistical pooling will not be possible due to
variations in the outcome measure reporting. No
subgroup analyses are planned; however, these will be
presented as provided by the authors if appropriate. The
whole umbrella review will be reported according to
Preferred Reporting Items for Systematic reviews and
Meta-Analyses (PRISMA) guidelines [
This review protocol outlines the process to carry out an
umbrella systematic review which will look at existing
reviews on childhood dental caries and body weight in
order to compare and contrast their findings. The
overall aim is to synthesise the available evidence in order to
provide an updated summary for policymakers and to
better inform healthcare interventions which make use
of the CRFA.
Additional file 1: PRISMA-P checklist for protocol CRD42016047304
(version 2.1). PRISMA-P (Preferred Reporting Items for Systematic review and
Meta-Analyses Protocols) 2015 checklist: recommended items to address in
a systematic review protocol. (PDF 278 kb)
Additional file 2: Search strategy—MEDLINE (Ovid). Search strategy
trialled in MEDLINE using EBSCO (search date: 06.10.16). (PDF 187 kb)
AMSTAR: A measurement tool to assess the methodological quality of
systematic reviews; CRFA: Common Risk Factor Approach; DMFS: Decayed,
Missing and Filled (tooth) Surfaces; DMFT: Decayed, Missing and Filled Teeth;
GBD: Global Burden of Disease; MeSH: Medical Subject Headings;
PRISMA: Preferred Reporting Items for Systematic review and Meta-Analyses;
PRISMA-P: Preferred Reporting Items for Systematic review and Meta-Analysis
We thank Andy Jackson, Medical Librarian at the University of Dundee, for
his advice in developing the search strategy.
This study is being completed as part of a PhD by research (SJC) at the
University of Dundee; there was no funding source for this review protocol.
Availability of data and materials
SJC led the design of the protocol, search strategy, drafting and revision of
the manuscript. RF was involved in the conception and design of the
protocol and drafting and revisions to the manuscript. MPH was involved in
the design of the protocol and drafting and revising of the manuscript. LA
and DR were involved in the drafting and revising of the manuscript. All
authors read and approved the final manuscript.
Ethics approval and consent to participate
Consent for publication
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
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