In vivo birefringence mapping of human gingiva using polarization-sensitive OCT

Optical Coherence Tomography (OCT) has emerged as a valuable tool for noninvasive, non-radiative, high-resolution imaging of gingival tissue, enabling structural assessment relevant to early diagnosis of periodontal disease. However, conventional intensity-based OCT provides limited contrast for birefringent components such as collagen, which play a central role in gingival integrity and disease progression. To address this limitation, Polarization-sensitive OCT (PS-OCT) extends OCT by resolving polarization states, enabling direct visualization and quantification of tissue birefringence. We present a custom-developed PS-OCT system operating at a 1310 nm center wavelength, with a 100nm bandwidth and 200 kHz A-line rate, designed for in vivo gingival imaging. The system captures co-registered intensity and polarizationresolved volumetric datasets from the interdental papilla region. To enhance the visualization of collagen microstructure, we applied streamline rendering of optic axis orientation, revealing distinct spatial patterns that delineate anatomical zones within the gingiva. In addition, quantitative analysis of phase retardation provided depth-resolved birefringence metrics that further characterize collagen integrity. These results demonstrate that PS-OCT, combined with birefringence mapping and quantitative retardation analysis, enables noninvasive, in vivo assessment of gingival collagen architecture. This technique offers promising potential for early detection and monitoring of periodontal disease. Future work will focus on expanding the imaging cohort and conducting broader clinical validation to establish the diagnostic utility of birefringence-based biomarkers in oral health.