Comparisons of the diagnostic accuracies of optical coherence tomography, micro-computed tomography, and histology in periodontal disease: an ex vivo study

Abstract

Purpose: Optical coherence tomography (OCT) is a noninvasive diagnostic technique that may be useful for both qualitative and quantitative analyses of the periodontium. Micro-computed tomography (micro-CT) is another noninvasive imaging technique capable of providing submicron spatial resolution. The purpose of this study was to present periodontal images obtained using ex vivo dental OCT and to compare OCT images with micro-CT images and histologic sections.

Methods: Images of ex vivo canine periodontal structures were obtained using OCT. Biologic depth measurements made using OCT were compared to measurements made on histologic sections prepared from the same sites. Visual comparisons were made among OCT, micro-CT, and histologic sections to evaluate whether anatomical details were accurately revealed by OCT.

Results: The periodontal tissue contour, gingival sulcus, and the presence of supragingival and subgingival calculus could be visualized using OCT. OCT was able to depict the surface topography of the dentogingival complex with higher resolution than micro-CT, but the imaging depth was typically limited to 1.2-1.5 mm. Biologic depth measurements made using OCT were a mean of 0.51 mm shallower than the histologic measurements.

Conclusions: Dental OCT as used in this study was able to generate high-resolution, cross-sectional images of the superficial portions of periodontal structures. Improvements in imaging depth and the development of an intraoral sensor are likely to make OCT a useful technique for periodontal applications.

Keywords: Diagnosis; Histology; Optical coherence tomography; Periodontal diseases.

Figure 1

Schematic diagram of the prototype OCT system based on a swept source that generates light with a center wavelength of 1,310 nm. OCT, optical coherence tomography.

Figure 2

Captured image of the canine tooth model on the software interface of the ex vivo OCT system. The graphs represent the amplitude of light backscattered from the tissue; the x- and y-axes represent the scanning range and depth, respectively. OCT, optical coherence tomography; T, tooth; GM, gingival margin; FG, free gingiva; SB, sulcus base.

Figure 3

OCT imaging of the canine dentogingival complex. (A) Supragingival calculus (arrow) is clearly visualized on the tooth surface. (B) Subgingival calculus (arrow) can also be seen below the gingival margin with a signal intensity similar to that of supragingival calculus. OCT, optical coherence tomography.

Figure 4

A tooth surface anomaly appears as increased signal intensity relative to adjacent surfaces, and is also evident in the amplitude graph (arrow).

Figure 5

Comparison of (A) OCT, (B) micro-CT, and (C) histology at the buccal furcation region of the second premolar of a canine specimen. The surface topography is more accurately revealed by OCT than by micro-CT. (A) The epithelial thickness appears as a brighter green coloration at the superficial surface of the gingiva, in comparison to the darker blue area corresponding to the loose connective tissue directly underneath. (B) Visualization of gingival soft tissue in a micro-CT image, but with less visual acuity than in the OCT image. Alveolar bone including the bone marrow space can be observed. (C) Histologic section showing the rete pegs of the epithelium lining the gingiva with adjacent loose connective tissue. Alveolar bone can be seen below the furcation with its marrow space. (H&E, ×10). OCT, optical coherence tomography; micro-CT, micro-computed tomography; H&E, hematoxylin and eosin; DEJ, dentinoenamel junction; CT, connective tissue; Epi, epithelium; AB, alveolar bone; BM, bone marrow; RP, rete pegs.

Figure 6

A Bland-Altman plot showing the differences in biologic depth measurements between OCT and histology. OCT, optical coherence tomography; SD, standard deviation.

Figure 7

Micro-CT images of the canine dentogingival complex in the (A) coronal and (B) sagittal planes. Three-dimensional reconstructed images are shown in the (C) distal, (D) buccal, and (E) occlusal planes. Micro-CT, micro-computed tomography.