PREreview of Cytokine profile of saliva in adults with focal enamel demineralization after orthodontic treatment

Summary of main findings and contribution

This preprint reports a small observational study measuring salivary cytokines (IL‑1β, IL‑6, IL‑8, IL‑4, IL‑10) in adults after long-term fixed orthodontic treatment. The authors report lower IL‑8 and IL‑4 in the FED groups and emphasize a higher IL‑6 (and altered IL‑6/IL‑4 and IL‑6/IL‑10 ratios) in the decompensated-caries subgroup, interpreting these as immune dysregulation relevant to FED pathogenesis.​

Major issues

• Core design confounding (FED vs caries vs orthodontic exposure): The study question is framed around FED after orthodontic treatment, but the groups are essentially stratified by caries intensity, and the comparison group is “practically healthy” without caries (and not clearly matched on orthodontic exposure), making it hard to attribute cytokine differences specifically to FED rather than to caries status and/or other differences between recruited populations.​

• Inconsistencies/ambiguity in group definitions and sample counts: The abstract states 26 patients divided into three groups including “patients without caries,” yet the Methods state 26 orthodontic-treated participants, FED diagnosed in 24, with two FED subgroups (n=10, n=14) plus a separate comparison group (n=10), which is internally confusing and affects interpretability of results and denominators.​

Minor issues

• Summary statistics vs nonparametric testing: The paper reports means ± (SD/SE) while using Mann–Whitney tests; the authors can consider reporting medians and IQR and provide effect sizes with confidence intervals for group differences.​​

Evidence appraisal

Overall strength of evidence is limited for claims about “key roles” of IL‑6/IL‑4 in FED pathogenesis, because the design is cross-sectional, small (FED subgroups n=10 and n=14), and strongly confounded by caries status and likely other unmeasured factors. Although the results are consistent with between-group differences in some cytokines/ratios in this specific sample, but causal or mechanistic inferences about FED are not well supported without better controls and more rigorous statistical control for multiplicity and confounding.​​

Recommendations for improvement

• Clarify the scientific contrast: Redesign or reframe analyses to cleanly separate effects of (a) FED presence/severity, (b) orthodontic exposure, and (c) caries intensity; at minimum add a bracket-treated group without FED and/or match controls on orthodontic history.​

• Strengthen reporting to STROBE: Add setting/recruitment dates, participant flow (screened/eligible/included/analyzed), missing-data counts per variable, and clearly prespecified objectives and primary endpoints.​​

• Add confounder measurement: Collect/report oral hygiene indices, dietary sugar frequency, gingival/periodontal inflammation measures, smoking status, medication use, and time since debonding.

Competing interests

The author declares that they have no competing interests.

Use of Artificial Intelligence (AI)

The author declares that they did not use generative AI to come up with new ideas for their review.