Effects of aging on DNA hydroxymethylation and methylation in human dental follicles.

OBJECTIVE: Despite the high frequency of impacted teeth and increased frequency of lesions in dental follicles (DF) with aging, DF age-changes remain unclear. We compared the global methylation and hydroxymethylation profiles in DF in relation to age. DESIGN: DF associated with impacted lower third molars were obtained from 59 individuals. Global DNA methylation (5mC content) and hydroxymethylation (5hmC) were evaluated by ELISA. We tested the correlation between 5mC and 5hmC content, and the correlation of each with patients' age. The differences in age, 5mC, and 5hmC in DF from men/women, and location (left/right mandible) was tested. RESULTS: The mean age of the 59 individuals was 19.56 ±â€¯3.92, ranging from 13 to 31 years, and most were women (n = 39). 5hmC content and age up to 19 years were inversely correlated (Spearman's correlation coefficient=-0.552, p = 0.0003, n = 38). There was no relationship between 5hmC and 5mC content. There was no difference in the medians of age (p = 0.25), 5hmC (p = 0.33) and 5mC (p = 0.86) between men/women, nor in the medians of age (p = 0.39), 5hmC (p = 0.99) and 5mC (p = 0.22) between the left/right side of the tooth extraction. CONCLUSION: An inverse correlation between 5hmC and age was established, with no correlation between 5mC and 5hmC content in DF. The biological meaning of such a decrease of global DNA hydroxymethylation with age in DF remains to be clarified.

Assessing pathogenic mutations in dental follicles as an attempt to identify early events in odontogenic tumours tumourigenesis.

OBJECTIVE: Driver oncogenic mutations have been reported in several benign neoplasms. While ameloblastomas show BRAF p.V600E mutations, adenomatoid odontogenic tumours harbour either KRAS p.G12R or p.G12 V. The lack of understanding of the core molecular changes involved in tumour initiation and progression represents a critical barrier to developing new strategies for cancer detection and prevention. Considering the fact that ameloblastoma and adenomatoid odontogenic tumours can originate from dental follicles, we hypothesized that the BRAF and KRAS mutations might be early events in odontogenic tumours tumourigenesis. We aimed to assess BRAF and KRAS mutations in dental follicles associated with asymptomatic impacted teeth. DESIGN: Forty-eight dental follicles containing odontogenic epithelial remnants were included in the study. As ameloblastomas most often occur in the posterior mandible and adenomatoid odontogenic tumours have a predilection for the anterior jaws, we assessed by allele-specific qPCR the presence of BRAF p.V600E in 32 dental follicles associated with impacted 3rd mandibular molar teeth and KRAS p.G12 V and KRAS p.G12R mutations in 16 dental follicle specimens obtained from around impacted anterior teeth. Sanger sequencing was used as an additional method. RESULTS: None of the dental follicle cases tested positive for the mutations. CONCLUSION: In conclusion, we tried to detect the early genetic events associated with odontogenic tumours development in dental follicles, but we were unable to showcase that BRAF p.V600E and KRAS p.G12R or p.G12 V mutations are the early genetic events associated with odontogenic tumours development.