Histological and whole-genome sequencing analysis of coronally advanced flap with connective tissue graft for the treatment of gingival recession—A case study

Background

Oral tissue morphogenesis is innately determined and genetically controlled by underlying connective tissue. The connective tissue graft (CTG) harvested from palatal donor sites originally retains “regional specificity” and is considered to be responsible for epithelial keratinization.

Methods

This case study presents histological and genomic outcomes of coronally advanced flap (CAF) with CTG for the management of marginal tissue recession (MTR). The tissue samples harvested at 12-month postoperative period, during the debulking procedure of the treated site were subjected to Masson's trichrome staining (MTS) and whole-genome sequencing (WGS).

Results

Clinically, the mean root coverage as compared to baseline at 6 months (90%), 12 months (95%), and 24 months (95%) postoperatively was achieved. Overbulking of treated site was evident even after 12 months. Nevertheless, clinically discernible alterations in epithelial keratinization were not present. Although MTS revealed areas of non-keratinization and para-keratinization, WGS revealed a significant expression of keratinization genes, neural crest, and positional marker genes.

Conclusions

CAF with CTG is still considered the “gold standard” in treatment of MTR. The keratinization of overlying epithelium at sites hitherto where non-keratinized mucosa is advanced over CTG may not be complete even after 12 months. It is evident from the analysis of the reported case that clinically such sites may appear non-keratinized despite the expression of genes for keratinization. The complex interplay between genomic and phenotypic expressions serves as a foundation of biological concepts. Nevertheless, it is imperative to acknowledge that the phenotype of an organism is not solely determined by genetic expression and is often influenced by a complex interaction between genetic background and environmental factors.

Key Summary

The connective tissue serves as a medium for transmitting the genetic code and exerting an influence on the properties of the overlying epithelial tissue.

• Concrete evidence implies connective tissue plays a significant role in influencing the keratinization process of the overlying epithelium.
• Epithelial keratinization following a coronally advanced flap with connective tissue graft is also governed by environmental factors in addition to inherent potential within the graft.
• Differences in gene expression profiles may vary from individuals, teeth and among sites.