High-Frequency Optical Coherence Elastography for Gingival Tissue Characterization: Variability in Stiffness and Response to Physiological Conditions.

Accurate measurement of gingiva's biomechanical properties in vivo has been an active field of research but remained an unmet challenge. Currently, there are no noninvasive tools that can accurately quantify tensile and shear moduli, which govern gingival health, with sufficiently high accuracy. This study presents the application of high-frequency optical coherence elastography (OCE) for characterizing gingival tissue in both porcine models and human subjects. Dynamic mechanical analysis, histology studies, and strain analysis are performed to support the OCE result. Our findings demonstrate substantial differences in tissue stiffness between supra-dental and inter-dental gingiva, validated by dynamic mechanical analysis and OCE. We confirmed the viscoelastic, nearly linear, and transverse-isotropic properties of gingiva in situ, establishing the reliability of OCE measurements. Further, we investigated the effects of tissue hydration, collagen degradation, and dehydration on gingival stiffness. These conditions showed a decrease and increase in stiffness, respectively. While preliminary, our study suggests OCE's potential in periodontal diagnosis and oral tissue engineering, offering real-time, millimeter-scale resolution assessments of tissue stiffness, crucial for clinical applications and biomaterial optimization in reconstructive surgeries.