Biomarkers Indicating Early Epithelial–Mesenchymal Transition Changes in Oral Epithelial Dysplasias: A Systematic Review

Background/Objectives. Oral epithelial dysplasia exhibits unpredictable behavior, prompting research to identify biomarkers that may help predict its progression to malignancy. This study aimed to ascertain the prognostic value of biomarkers indicative of the epithelial–mesenchymal transition (EMT) process using immunohistochemistry. Methods. A systematic review was conducted using PubMed data from 1978 to June 2026. Articles that employed immunohistochemistry to identify cells exhibiting epithelial–mesenchymal transition changes in oral epithelial dysplasia were included. Exclusion criteria included in vivo studies, book chapters, reviews, conference abstracts, and studies lacking population descriptions. The risk of bias was assessed using the “JBI Checklist for Critical Appraisal of Case Series”. Results. A total of 21 articles were included, analyzing 57 biomarkers: 34 epithelial, 19 mesenchymal, two cell-proliferation biomarkers, and two tumor-suppressor biomarkers. The sample sizes varied significantly between the studies. Most articles employed semiquantitative assessment, cell percentage, and immunostaining intensity, with 12 demonstrating low risk of bias. Conclusions. Studies with conclusive results and a low risk of bias suggest that E-cadherin and Vimentin are valuable biomarkers for identifying early EMT in OED. However, the lack of statistical support means that this assertion should be viewed with caution.