LAUSR

BACKGROUND Our objective was to develop and test a combined Raman microspectroscopy (RMS) and micro-optical coherence tomography (μOCT) approach for chairside quantification of gingival collagen, DNA, epithelium and connective tissue. We hypothesized that a high-resolution RMS/μOCT can characterize healthy and inflamed periodontal tissues for diagnosis and disease activity monitoring. METHODS A prototype instrument was developed, tested ex-vivo on gingival specimens and optimized for in-vivo intraoral use. The primary outcome measures were the ratios of oral epithelium to connective tissue thickness (OE:CT) and the amount of DNA to collagen type I (DNA/Col), and the thickness of sulcular epithelium (SE). For ex-vivo testing, 8 subjects with healthy periodontal tissues or with stage II-IV periodontitis were included in the study and underwent crown-lengthening or periodontal surgical procedures respectively. Gingival biopsies were scanned by RMS/μOCT and histometric analyses were performed. The proof-of-concept study included OE/CT, DNA/Col and SE assessed in 6 volunteers with or without signs of gingival inflammation (n = 3/group). RESULTS The spatially co-registered RMS spectra revealed opposing changes in the collagen and DNA peaks of inflamed compared to healthy tissues (p<0.05). Combined RMS/μOCT analysis showed that OE/CT, DNA/Col, and SE are significantly different between healthy and inflamed sites (p<0.05). Histological assessments confirmed the differences detected by RMS/μOCT. Qualitative analysis of DNA/Col ratios indicated Col I content as the main distinguishing feature for health and DNA content for periodontitis. CONCLUSION Results suggest that combined RMS/μOCT chairside imaging may distinguish between healthy and diseased sites by evaluating marginal periodontal morphological and biochemical features. This article is protected by copyright. All rights reserved.