The many gingival fibres that connect the tooth to the gingiva, the tissue region that surrounds our teeth, allow healthy teeth to firmly rest in the gums.

Fibroblasts, which are cells that help connective tissue form, are found in the gingiva. Researchers from Tohoku University have shown that gingival stiffness impacts the characteristics of gingival fibroblasts, which in turn affects the likelihood of inflammation and how challenging it is to generate gingival fibres.

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Their findings were published in the journal Scientific Reports on January 24, 2023. “We discovered that soft gingiva results in inflammation and hinders the development of gingival fibers,” says Associate Professor Masahiro Yamada from Tohoku University’s Graduate School of Dentistry.

It has long been known that individuals with thick or stiff gingiva are less susceptible to gingival recessions. This is where the gingiva begins to recede and expose a tooth’s root. Many factors can lead to gingival recession, such as gum disease, over-brushing, and chewing tobacco. But this is the first time that gingival stiffness has been attributed to biological reactions.

Although fibroblasts play an important role in the maintenance, repair and healing of the gingiva, they also produce various inflammatory and tissue-degrading biomolecules which degrade the gingival fibers. In addition, fibroblasts are associated with immune responses to pathogens.

Yamada, along with his colleague Professor Hiroshi Egusa, also from the Tohoku University’s Graduate School of Dentistry, created an artificial culture environment that simulated soft or hard gingiva and cultured human gingival fibroblasts on them. They discovered that hard gingiva-simulated stiffness activated an intracellular anti-inflammatory system in the gingival fibroblasts that prevented inflammation. Yet, soft gingiva-simulated stiffness suppressed the fibroblastic anti-inflammatory system. This increased the likelihood of inflammation and resulted in less collagen synthesis.

“Our research is the first to demonstrate the biological mechanisms at play in regard to a patient’s gingival properties,” added Yamada. “The results are expected to accelerate the development of advanced biomaterials to control local inflammation or microdevices that simulate the microenvironment of inflammatory conditions.”