Project:
Visualization of Pulpal Structures by SWIR in Endodontic Access Preparation

Abstract:
The aim of the research project was to evaluate the use of shortwave-infrared radiation (SWIR) for navigation during stepwise access preparation. Nine teeth (3 anteriors, 3 premolars and 3 molars) were explanted en bloc with intact periodontium including alveolar bone and mucosa from the upper or lower jaw of human body donors. Because of body donors advanced age samples include clinically realistic and relevant features such as pulp obliterations, caries and restorations. A stepwise preparation was used to observe optical changes on the cavity floor with increasing preparation depth. At baseline (T0) and at preparation depths of 5 mm (T1), 7 mm (T2), and 9 mm (T3), white light pictures, radiographs, SWIR transillumination (SWIRT) and SWIR reflection (SWIRR) images were taken. At T2, µCT images of the samples were acquired and anatomically segmented into 3D-tooth models including enamel, dentin, pulp and bone. Radiomic feature analysis was performed on pulpal and parapulpal areas in SWIRT images at T2. 

Ziel des Forschungsprojekts war es, die Verwendung von Nahinfrarotem Licht zur Navigation beim schrittweisen endodontischen Zugang zu bewerten. Neun ZŠhne (3 FrontzŠhne, 3 PrŠmolaren und 3 Molaren) wurden en bloc mit intaktem Zahnhalteapparat einschlie§lich Alveolarknochen und Schleimhaut aus dem Ober- oder Unterkiefer menschlicher Kšrperspender explantiert. Aufgrund des fortgeschrittenen Alters der Kšrperspender enthielten die Proben klinisch realistische und relevante Merkmale wie PulpaverfŠrbungen, Karies und Restaurationen. Es wurde eine schrittweise PrŠparation durchgefźhrt, um optische VerŠnderungen am KavitŠtenboden mit zunehmender PrŠparationstiefe zu beobachten. Zu Beginn (T0) und bei PrŠparationstiefen von 5 mm (T1), 7 mm (T2) und 9 mm (T3) wurden Wei§lichtbilder, Ršntgenbilder, Transilluminations- und Reflexionsbilder aufgenommen. Zum Zeitpunkt T2 wurden µCT-Bilder der Proben aufgenommen und anatomisch in 3D-Zahnmodelle mit Schmelz, Dentin, Pulpa und Knochen segmentiert. Die radiomische Merkmalsanalyse wurde fźr pulpŠre und parapulpŠre Bereiche in Transilluminations-Bildern bei T2 durchgefźhrt.

Keywords:
Optical Imaging, X-Ray Microtomography, 3-D Imaging, Segmentation, Radiomics

Methods and Data acquisition:
White light images were taken with a single-lens reflex camera (Nikon, Tokyo, Japan) with a lens (AF-S 18-105mm, f/3.5-5.6, Nikon) and a ring flash (EM-140 DG, Sigma, Kawasaki, Japan).
Two-dimensional radiographs were taken using the parallel technique with a Heliodent DS dental X-ray unit (60 kV, 7 mA, 0.06 s exposure; Sirona, Bensheim, Germany) and a charge-coupled sensor "Intra-Oral II" (sensor size 30.93 * 40.96 * 7.0 mm; Sirona). The images were acquired with the Sirona SIDEXIS XG software (V2.63 2016; Sirona).
Near-infrared reflection images were acquired with a LED emitting light at 1550 nm wavelength (M1550L3, Thorlabs) and an InGaAs camera (WiDy Sens 320 V-ST, resolution 320 x 256, New Imaging Technologies, VerriŹres-le-Buisson, France) with a 50-mm objective (LM50HC-SW, KOWA, Nagoya, Japan) in occlusal view on the specimens.
Near-infrared transillumination images were acquired with a LED that emits light at 1300 nm wavelength (BYF1000LS02/ M1300F1, Thorlabs, Newton, NJ, USA) and an InGaAs camera (WiDy Sens 320 V-ST, resolution 320 x 256, New Imaging Technologies, VerriŹres-le-Buisson, France) with a 50-mm objective (LM50HC-SW, KOWA, Nagoya, Japan) in occlusal view on the specimens.
For µCT images, specimens were scanned in three dimensions using a fully shielded cone-beam µCT40 table-top scanner (Scanco Medical, Bassersdorf, Switzerland). The scanner was operated at 70 kV and 114 µA with a field of view of 16.5 mm. The scan resolution was 512 * 512 points with a voxel size of 0.032 mm.
3D models of µCTs were created by manual segmentation of enamel, dentin and pulp in 3D-Slicer (http://www.slicer.org, v5.6.1).

Data index:
Labeling of files based on Index (anterior, premolar and molar), sample-number, toothtype, timepoint, imagetype, tooth surface and file type: 
"[Toothtype]_[SampleNumber]_[Tooth]_[Timepoint]_[ImageType]_[ToothSurface].[Filetype]".

Data formats:
jpeg, tiff, nef, pdf, nrrd