Near-infrared endoscopic imaging of deep artificial interproximal lesions in extracted teeth

摘要

Near-infrared (NIR) dental imaging using scanning fiber endoscope (SFE) is being developed with advantages ofminiature size (1.6mm), flexible shaft, video frame rate (7Hz), and expandable field of view (60 degrees). Using 1310,1460, and 1550 nm laser diodes, the multispectral NIR SFE provides high contrast of lesion with transparency of stainedand non-calcified plaque. However, capabilities of scanned NIR imaging remain unknown. Artificial interproximallesions are created in extracted human posterior teeth by preparing a cavitation on the mesial or distal surface and thenthe cavitated artificial lesions were filled with hydroxyapatite powder and sealed with cyanoacrylate resin. Lesions areprepared at different occlusal-gingival depths from marginal ridges, lesion drilling depths and lesion size. Endoscopicreflectance images were acquired and compared to micro-CT scans and 1310 nm OCT images of the lesions to evaluateperformance of the nirSFE. Results show that NIR SFE can image deep lesions under sound enamel with thickness of≤4mm. All three wavelengths can detect deep lesions through the occlusal enamel which are not visible by naked-eye.1460 nm has the highest contrast between lesion and sound enamel while 1310nm more clearly shows the contrastbetween enamel and dentin. Our nirSFE system can detect artificial interproximal lesions less than 4 mm below theocclusal surface, distinguish different drilling depth both in enamel and in dentin layer. Furthermore, the nirSFE realtimeimaging and video functionality renders better lesion contrast and helps distinguish specular reflection and lesionsignal. In conclusion, the NIR SFE has the potential to measure volume of these lesions due to the many viewing anglesachievable by the miniature and flexible probe tip.