Cellular porosity in dentin exhibits complex network characteristics with spatio-temporal fluctuations

Area of Science:

• Biophysics
• Dental Research
• Network Science

Background:

• Tooth sensitivity is linked to fluid flow in dentin's porous structure.
• Odontoblast cell processes are activated by this fluid flow, according to hydrodynamic theory.
• Understanding dentin's porosity topology is key to explaining these phenomena.

Purpose of the Study:

• To investigate the topology and connectivity of dentinal porosity in a healthy human tooth.
• To model dentin porosity as a spatial graph to analyze its network characteristics.
• To assess the impact of network structure on fluid flow and mechanosensing.

Main Methods:

• Confocal fluorescence microscopy was used to visualize and model dentin porosity.
• Porosity was represented as a spatial graph, with tubules/branches as edges and connections as nodes.
• Graph metrics were analyzed to quantify network topology, connectivity, and resilience.

Main Results:

• A significant portion of crown dentin porosity (47% of nodes) is interconnected over millimetric distances from the dentin-enamel junction (DEJ).
• A sharp decrease in connectivity (83% to 43%) was observed at 300 µm from the DEJ, correlating with early tooth formation stages.
• Network resilience decreased by a factor of 2, highlighting structural changes with depth.

Conclusions:

• Dentin porosity exhibits complex network characteristics, with lateral branches playing a critical role.
• The study provides a framework for interpreting graph metrics from microscopy data.
• Accurate modeling of fluid flow in dentin's complex network is essential for understanding odontoblast mechanosensing and tooth sensitivity.