Exploiting Nanomaterials for Optical Coherence Tomography and Photoacoustic Imaging in Nanodentistry

Abstract

There is already a societal awareness of the growing impact of nanoscience and nanotechnology, with nanomaterials (with at least one dimension less than 100 nm) now incorporated in items as diverse as mobile phones, clothes or dentifrices. In the healthcare area, nanoparticles of biocompatible materials have already been used for cancer treatment or bioimaging enhancement. Nanotechnology in dentistry, or nanodentistry, has already found some developments in dental nanomaterials for caries management, restorative dentistry and orthodontic adhesives. In this review, we present state-of-the-art scientific development in nanodentistry with an emphasis on two imaging techniques exploiting nanomaterials: optical coherence tomography (OCT) and photoacoustic imaging (PAI). Examples will be given using OCT with nanomaterials to enhance the acquired imaging, acting as optical clearing agents for OCT. A novel application of gold nanoparticles and nanorods for imaging enhancement of incipient occlusal caries using OCT will be described. Additionally, we will highlight how the OCT technique can be properly managed to provide imaging with spatial resolution down to 10′s–100′s nm resolution. For PAI, we will describe how new nanoparticles, namely TiN, prepared by femtosecond laser ablation, can be used in nanodentistry and will show photoacoustic microscopy and tomography images for such exogenous agents.

Gold nanomaterials for oral cancer diagnosis and therapy: Advances, challenges, and prospects

“…The results showed that OCT detection with AuNPs improved resolution by 150%. However, due to absorption and scattering limitations, the penetration depth is only a few millimeters [ 105 ], so further investigation and improvements are needed for better clinical use. In recent years, a new optical technique, diffuse reflectance spectroscopy (DR), has been developed for biological imaging.…”

Looking deep inside tissue with photoacoustic molecular probes: a review

“…On the other hand, PAI can achieve deep tissue imaging at a few centimeters, but it has a lower spatial resolution than OCT. To overcome the penetration depth-resolution duality, a combination OCT+PAI system was reported. 283 For example, contrast-enhanced dual-modal OCT/PAM for evaluating retinal diseases was shown with gold nanostars. 166 Functionalized with an RGD peptide, the gold nanostars exhibited strong optical absorption in the NIR window and excellent photostability, leading to visualization of choroidal neovascularization.…”

Three-dimensional imaging and quantification of mouse ovarian follicles via optical coherence tomography

“…Without the use of contrast agents, it can non-invasively provide three-dimensional (3D) images with micrometer scale resolution, yielding millimeter-scale depth information. It has been largely adopted in the ophthalmic field for imaging retina-related disease 7,8 , but also has found applications in other fields, such as dermatology 9 , rheumatology 10 , dentistry 11 , cardiovascular medicine 12 , and in developmental biology and organoid models 13 . OCT may be employed in selecting ovary tissue with the highest density of primordial follicles for cryopreservation and/or reimplantation.…”