Advanced imaging of dentin microstructure

Abstract

This study aimed to demonstrate the feasibility of using optical coherence tomography (OCT) for locating the sectioning site of a specimen before characterizing the ultrastructural features of dentin surfaces as well as the inner wall of the dentinal tubules (DT) using a field emission scanning electron microscope (FESEM). Eight sound human molar teeth were extracted, examined via crosspolarization optical coherence tomography (CP-OCT), embedded, and hemisectioned using a lowspeed diamond sawing machine. Next, each sectioned surface was further trimmed, polished, and examined under a confocal laser scanning microscope (CLSM) to locate the target area on the superficial dentin. Subsequently, each section was gold-coated and examined using FESEM. Backscattered reflection from the dentin layer was less than that from the enamel under CP-OCT. Distinct reflections from certain enamel and dentin microstructures were observed before sectioning the specimens. Areas with enamel cracks and dentin defects were identified and avoided during sectioning. At the micron level, the CLSM images exhibited a homogenous distribution of the DT orifices. Low magnification FESEM images showed intertubular dentin as a loosely condensed globular layer with shallow grooves in between, whereas peritubular dentin exhibited more organized condensation of apatite crystals surrounding the DT orifices. High magnification of the DT revealed a cross-linking layer of mineralized collagen network extending in the peri-intratubular lumen, with scattered globules of matrix vesicles. CP-OCT enabled the realization of rapid initial scanning and image acquisition with high contrast at the micron scale before profound insights into dentin ultrastructures at the nano scale were provided by FESEM. The variations in structural densities of the dental tissues significantly affected the image contrast and helped identify underlying structures.

Sample Preparation of Atherosclerotic Plaque for SAXS/WAXS Experimentation

“…It was concluded that another method of fixation and sample preparation was required that would allow both thicker samples and the hydroxyapatite to remain within the CEA sections. Previously, teeth have been sectioned by embedding the tooth in epoxy resin and sectioning using a low-speed cutting machine under a water coolant . Hydroxyapatite is the main mineral in the enamel of teeth, and as it is also found in atherosclerotic plaques, this suggests this method would be suitable for sectioning of the plaques.…”

“…Previously, teeth have been sectioned by embedding the tooth in epoxy resin and sectioning using a low-speed cutting machine under a water coolant. 31 Hydroxyapatite is the main mineral in the enamel of teeth, 32 and as it is also found in atherosclerotic plaques, this suggests this method would be suitable for sectioning of the plaques. Samples were fixed in glutaraldehyde and embedded in epoxy resin.…”

Effect of cigarettes smoke on bonded polymeric restorations: OCT study

“…It was also suggested that an increase in temperature may lead to a release of the resin monomer [ 41 ]. Another study concluded that CS did not affect the surface roughness of composite restorations; however, it influenced the surface gloss and increased the staining possibilities due to the interaction between CS and composite filler content [ 10 ].…”

“…Tars contain pigmented compounds and metal ions, such as lead and cadmium [ 8 ]. Dentin is a heterogeneous, wet, and organic substrate compared to enamel, making bonding to this substrate more challenging [ 10 , 11 ]. Proper adhesion mandates intimate contact with the tooth surface when bonding restorative materials to dental substrates.…”

Non-Destructive In Vitro Evaluation of an Internal Adaptation of Recent Pulp-Capping Materials in Permanent Teeth Using OCT and Micro-CT

“…This technique has many merits, including non-invasiveness, visibility of hard and soft tissues, and lack of radiation with excellent spatial resolution [ 26 , 27 ]. OCT allows for real-time imaging of tissue sections without the need for biopsy, histological procedures, or X-rays, in a non-contact and non-invasive manner [ 28 , 29 , 30 , 31 ]. The benefits mentioned have been verified in a prior investigation that established the capability of MCT and OCT to identify, without causing damage, the sealing ability of the pulp-capping agents in primary teeth.…”