Multispectral SWIR images of the pulp-chamber of posterior teeth in vitro

Abstract

Intraoral imaging of teeth with SWIR light provides increased contrast of dental caries and restorative materials compared to visible inspection and digital radiography. The objective of this study was to investigate the SWIR optical properties of the dental pulp-chamber floor, walls and canal orifices. We imaged in vitro extracted human posterior teeth at 1300-nm and 1500-1700-nm in reflectance and transillumination and compared the tissues properties with visible light images and quantitative light fluorescence. Transillumination of posterior teeth at both 1300-nm and 1500-1700-nm yielded significantly higher contrast between the pulp-chamber floor and walls than all other methods tested.

Keywords: SWIR imaging; detection; endodontics; reflectance; root canal; transillumination.

Fig. 1.

Reflectance and transillumination images of a mandibular molar, (A) visible reflectance before sample preparation, (B) visible reflectance, (C) QLF reflectance, (D) BP1300-nm reflectance, (E) BP-1300-nm reflectance, (F) LP1500-nm reflectance, (G) visible transillumination color, (H) visible transillumination greyscale, (I) BP1300-nm transillumination, and (J) LP1500-nm transillumination.

Fig. 2.

Contrast values for each modality and spectral region between the pulp-chamber floor and walls. SWIR wavelengths outperformed visible light producing greater contrast of pulp chamber anatomy.

Fig. 3.

Reflectance and transillumination images of a mandibular second molar, (A) visible reflectance before sample preparation, (B) visible reflectance, (C) QLF reflectance, (D) BP1300-nm reflectance, (E) BP-1300-nm reflectance, (F) LP1500-nm reflectance, (G) visible transillumination color, (H) visible transillumination greyscale, (I) BP1300-nm transillumination, and (J) LP1500-nm transillumination.