Assessment of traumatic injuries using swept-source optical coherence tomography

Objectives: Optical coherence tomography (OCT) is a promising diagnostic method for creating cross-sectional imaging of internal biological structures by measuring backscattered light. The purpose of this in vitro study was to investigate the ability of swept-source OCT (SS-OCT) to detect traumatic injuries of teeth, especially for cracks. 

Methods: SS-OCT (OCT-2000, Santec) system with a laser center wavelength of 1310nm was used. Tooth cracks were created by subjecting 30 porcine premolars to impaction by a steel rod plunging from the occlusal tip. SS-OCT images and stereomicroscopic photographs of the surface were acquired for each sample before and after impaction. The focused light beam of SS-OCT was projected from three directions on the same plane; buccal or lingual, 45° to the mesial, and 45° to the distal for evaluation. Histological sections were prepared after impaction, and crack line length and width were evaluated with the corresponding SS-OCT image. The values were statistically analyzed using Pearson’s correlation coefficient. 

Results: In SS-OCT, cracks were clearly detected as intensified scattering signals at the same position of the corresponding microphotographs and histological sections. Among the 3 scanning angles, the longest lines were considered the corresponding values of SS-OCT and used for analysis. There were significant correlations regarding the line length and width between SS-OCT and histological sections (length: r = 0.738, p<0.001, width: r = 0.532, p<0.05) 

Conclusions: SS-OCT can clearly discriminate tooth cracks, which appear as highlighted lines due to the scattering of light. The results obtained from 3 scanning directions were well correlated with the histological sections. OCT has potential for diagnosis of traumatic injuries clinically, especially in infants and children. This work was supported by the Research Funding for Longevity Sciences (22-2) from NCGG, Japan.