Micrometer-Scale Biomechanical Characterization of Oral Mucosa Using Spatial Phase-Gradient Tracking Optical Coherence Elastography.

We present a custom-built, high-speed optical coherence elastography (OCE) system for non-invasive, quantitative assessment of oral tissue biomechanics. The system integrates low-frequency (10 Hz) air-driven elastic wave excitation with phase-resolved optical coherence tomography (OCT) for micrometer-scale elasticity mapping. A pilot study on human buccal mucosa (four healthy, four cancerous, one leukoplakia) revealed distinct biomechanical contrasts. Healthy tissues exhibited regular elastic wave propagation (≈2.5 μm displacement; 2.72 ± 0.27 Pa modulus), while cancerous samples showed restricted displacement (≈1 μm; 9.51 ± 0.95 Pa), indicating increased stiffness. The elastograms also visualized keratin layer thickening, rete peg elongation, and mild inflammatory infiltration. The leukoplakia specimen demonstrated intermediate stiffness (5.47 ± 0.55 Pa), suggestive of early biomechanical alteration. The integration of air-pressure excitation with phase-resolved OCT enables a non-contact, repeatable, and sensitive elastographic method capable of detecting subtle mechanical changes, highlighting the system's potential for early oral cancer diagnosis and soft tissue biomechanical characterization.