Development of optical coherence tomography incorporated image processing algorithms for the multidimensional assessment of concealed enamel micro-crack

Enamel microcracks (EMCs) are tiny fractures that occur in the outer layer of teeth, allowing some extrinsic stains and leading to an unaesthetic tooth. Additionally, the EMCs enhance the accumulation of plaque and thus EMCs could be highly suspectable zones for caries development. Therefore, the assessment of EMCs is crucial for early diagnosis and to prevent unwanted damage to teeth. In this study, a concealed EMCs detection and length-measuring algorithm, and an EMCs width-measuring algorithm were applied for optical coherence tomography (OCT) image analysis to assess the EMCs progression in both length and width. Additionally, a surface noise-removing algorithm was developed to obtain a better visualization of OCT cross-sectional and volumetric images. The developed algorithms were successfully used to detect concealed EMCs and track their progression in both length and width directions before and after the orthodontic treatment. Obtained results revealed a micro-scale progression of EMCs in both length and width directions after the orthodontic treatment, where the averaged progression of EMCs in length and width were 712.5 and 92.75 µm, respectively. Therefore, high-resolution, non-invasive OCT imaging with developed image processing algorithms can be a fruitful solution to use as a diagnostic tool to monitor the precise coordinates of concealed EMCs throughout the orthodontic treatment.