mRNA expression of DNA methylation machinery genes in periapical granuloma and their potential relationship with periapical wound healing

This study was designed to explore the relative expression of DNA methylation machinery genes in periapical granuloma and to assess longitudinal changes in gene expression within the healing group at 6 and 12 months. A total of twenty-seven patients (13 chronic apical periodontitis and 14 chronic apical abscess) underwent surgical endodontic treatment. During surgical endodontic treatment, periapical lesion tissue was collected and used for relative expression analysis of the following DNA methylation machinery genes: DNMT-1, TDG, TET-1, TET-2, and TET-3. These patients were subsequently re-appointed after 6 and 12 months for the evaluation of the periapical healing based on the established clinical and radiographic criteria. Quantitative PCR (qPCR) was employed for gene-expression analysis. Statistical analysis was performed using unpaired t-tests and a p-value < 0.05 was considered statistically significant. Post-operative healing was observed in 21 out of 27 patients (77.8%) after 12 months, whereas 6 patients (22.3%) showed no signs of healing at the end of the follow-up period. A statistically significant difference was observed in the expression of the TET-3 genes in chronic apical abscess. Moreover, TDG, TET-2, and TET-3 exhibited a positive fold change in healed chronic apical abscess samples (H + 12 M and H + 6 M) compared to non-healed (NH) samples. The significant differences in the expression of TET-3 gene, may suggest their potential role as epigenetic markers warranting further validation.