Staging of non-cavitated fissure caries (NCFC) enables timely detection and reversal of NCFC. Objective: The objective of study was to assess the performance of OCT in determining stages of NCFC using OCT backscatter intensity profile (A-scan). Methods: 90 investigation sites (ISs) from 46 extracted human premolars with NCFC were initially scored using ICDAS code 1 and 2. 3-dimensional scans of 3mm in x-y-z axis were performed using a Swept-source OCT. The ISs were sectioned and imaged using Polarized Light Microscopy (PLM). Final cohort were selected on PLM image using Ekstrand (Ek) histology criteria with Ek1=30 and Ek2=60 ISs. The corresponding OCT B-scan was selected based on fissure anatomy and processed using bespoke software developed in MATLABTM. Mean A-scan was generated from 50 A-scans at each ISs and an overall mean A-scan for each Ek code was computed. Total Area-under-the-curve (AUCT) between physical depths of 0-150μm subsurface was computed for each Ek code.
Kruskal Wallis analysis followed by post hoc Dunnet T3 test showed that AUCT of Ek1 was significantly different from Ek2 (p < 0.05). The mean difference between Ek1 and Ek2 was -1.57E10 a.u. AUCT showed detection sensitivity of 0.61 and specificity of 0.73 at a cut-off value of 7.031E+10 a.u with area under receiver operating characteristic curve (ROC) of 0.66 (p < 0.05). Conclusion: OCT has potential to differentiate NCFC using A-scans.