Income Inequalities and Dental Caries in 12-Year-Olds: An Ecological Comparison Between a High- and a Lower-Middle-Income Country
, Wayne Richards 1, Jamal Ameen 1, Anne-Marie Coll 1 and Teresa Filipponi 1Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsComment 1: lines 84-85: A reference supporting this statement should be included.
Comment 2: Lines 272 and 273 should also be included in the Materials and Methods section, specifically under the subsection Outcome Variables for Wales. (Line 123)
Comment 3: limitations should be addressed either as the final paragraph of the discussion or in a separate section.
Comment 4: The conclusions should be presented as a separate section.
Comment 5: It has not been specified whether the study received any form of funding, after author contributions section.
Funding: All sources of funding of the study should be disclosed.
Comment 5: In the text, reference numbers should be placed in square brackets [ ], and placed before the punctuation; for example [1], [1–3] or [1,3]. For embedded citations in the text with pagination, use both parentheses and brackets to indicate the reference number and page numbers; for example [5] (p. 10). or [6] (pp. 101–105).
Comment 6: It is mandatory to adapt the references to the journal’s publication guidelines.
https://www.mdpi.com/authors/references
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors of the paper «Income Inequalities in Dental Caries and Dental Care Levels Among 12-Year-Old Children; An Ecological Study in a High-Income Country and a Lower Middle-Income Country» assessed the association of income with dental caries experience and dental care levels among 12-year-old children in Sri Lanka (lower-middle-income) vs. Wales (high-income). They found the evidence of income-related disparities in dental caries in both countries.
The article is well-written, the language is understandable and correct; there are only several minor comments to be addressed.
Introduction
It seems to be too many references (I.e., first paragraph ref. No 2 repeated after each sentence; reference no. 6 in lines 54-59).
lines 54-55. «Systematic reviews have reported evidence for socio-economic inequalities in dental caries» it is supposed that such phrase would have more than one reference. Otherwise, it would be better to write «a systematic review».
The methodology is sound and well-described. For SPSS, please, add manufacturer, country, etc.
Discussion is thorough and detailed enough. It is recommended to discuss the differences between the measures for Sri-Lanka and Wales (Welsh Index of Multiple Deprivation vs. income, and the Gini coefficient).
The conclusion is supported by the results.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Authors,
Thank you for the opportunity to review your manuscript. The topic is relevant and timely, and the comparative approach between two countries with different economic backgrounds provides valuable insights. Below you will find detailed feedback intended to help improve the clarity, methodological transparency, and overall impact of your work.
- Relevance and originality
The topic is relevant from a public health perspective and presents an interesting comparison between two very different economic contexts (Sri Lanka and Wales).
The originality lies in linking income, income inequality, and dental caries experience in the same age group. However, the paper is largely descriptive and correlational, without developing the analysis toward deeper mechanistic or causal implications.
It would be useful to argue more clearly why the comparison between these two countries (and not others) is relevant for the generalization of conclusions.
- Title and abstract
The title reflects the content but could be reformulated for clarity, e.g.: “Income Inequalities and Dental Caries in 12-Year-Olds: An Ecological Comparison Between a High- and a Lower-Middle-Income Country”.
In the abstract:
Clearly state that the design is ecological and what limitations it implies, to avoid causal interpretation.
Include the mean DMFT values for each country.
- Introduction
The introduction is detailed but relatively long; some passages (e.g., global statistics) could be condensed.
Although recent literature is cited, a clearer discussion of the gaps in previous research that justify this study would be useful.
- Methods
Explain more clearly why data from different years were used (2014 for WIMD vs. 2015/2016 for oral health data) and how this could affect results.
Highlight the lack of an absolute income measure for Wales as an important limitation.
Present earlier in this section the methodological differences in caries recording (DMFT vs. D3MFT), not only in the limitations.
Indicate the sample size for each district/unitary authority.
- Results
Tables are dense; reformat for readability.
Add confidence intervals directly into the tables, not only in the footnotes.
Define clearly what thresholds are used for terms such as “positive” or “moderate” correlations.
- Discussion
Clearly mark statements that are hypotheses (e.g., sugar consumption) and separate them from actual results.
Emphasize more strongly the risk of ecological fallacy and the fact that individual-level conclusions cannot be drawn.
Discuss more explicitly how methodological differences in measuring caries and income could affect comparability.
Add a more structured section on the practical implications for public health policy.
- Other observations
Some in-text references are inconsistently formatted (e.g., [6] without a space).
Check consistency of monetary units and conversions.
Give descriptive titles to figures (e.g., “Relationship between income measures and DMFT in Sri Lanka”).
Consider adding a simple comparative graph between the two countries, not only separate tables.
- Conclusion
Reformulate the conclusion to clearly reflect the ecological nature of the study and its methodological limitations.
Avoid wording that suggests causality; focus on observed associations and recommendations for future research.
Shorten the conclusion slightly and retain only the key messages.
- References
Standardize reference formatting (spacing, punctuation, style).
Ensure consistency in citation style (articles, reports, links, DOI).
Best regards,
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Authors,
Thank you for your thorough revision of the manuscript. I have carefully reviewed the updated version, and I can confirm that the requested modifications have been addressed appropriately. In my opinion, the manuscript now meets the necessary scientific standards and is ready for publication.
Best regards,
