Abstract
This study aimed to determine the feasibility of using optical coherence elastography to measure internal displacements during the curing phase of a light-activated, resin-based composite material. Displacement vectors were spatially mapped over time within a commercial dental composite. Measurements revealed that the orientation of cure-induced displacement vectors varied spatially in a complex manner; however, each vector showed a systematic evolution with time. Precision of individual displacements was estimated to be ∼1 ∼1 to 2 μm 2 μm , enabling submicrometer time-varying displacements to be detected.
Highlights
Light-activated, resin-based composites (RBCs) are widely used in both industry[1] and medicine.[2]
Displacement precision was greater laterally compared to axially. This is because the lateral pixel spacing (6.9 μm) was ∼ð6.9 μm − 9.1 μmÞ∕9.1 μm 1⁄4 24% smaller than the lateral point spread function (PSF) full width half maxima (FWHM) (9.1 μm), compared to the axial pixel spacing (9.5 μm) that was ð9.5 μm − 7.8 μmÞ∕7.8 μm 1⁄4 21% larger than the corresponding axial PSF FWHM (7.8 μm)
Lateral sampling density can be controlled experimentally, for this work it was preferred to maximize the scan width relative to the number of A-scans permitted by the specific optical coherence tomography (OCT) implementation
Summary
Light-activated, resin-based composites (RBCs) are widely used in both industry[1] and medicine.[2] In dentistry, they have largely replaced mercury-based dental.[3]. Light cure RBCs are typically composed of a monomer (i.e., bisGMA, UDMA, TEGDMA), a filler material (silica and various bioglasses), and a photoinitiator system (Camphorquinone/ dimethylaminoethyl methacrylate).[1,2] Illumination of the RBC with light, corresponding to the photoinitiator absorption wavelength initiates polymerization and consequent hardening of the resin into a solid material. Varying degrees of polymerization[10] are expected to result in a spatially varying elastic modulus.[11]
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