Assessment of Demineralization Inhibition Effects of Dentin Desensitizers Using Swept-Source Optical Coherence Tomography.

Kumiko Matsuzaki,Yasushi Shimada,Kozo Yamaji,Junji Tagami,Masahiro Yoshiyama,Alireza Sadr,Yasuo Shinno,Serina Ono,Naoko Ohara,Yasunori Sumi

doi:10.3390/ma14081876

Abstract

The purpose of this study was to evaluate the mechanism of action and the inhibiting effects of two types of desensitizers against dentin demineralization using pre-demineralized hypersensitivity tooth model in vitro. In this study, we confirmed that a hypersensitivity tooth model from our preliminary experiment could be prepared by immersing dentin discs in an acetic acid-based solution with pH 5.0 for three days. Dentin discs with three days of demineralization were prepared and applied by one of the desensitizers containing calcium fluoro-alumino-silicate glass (Nanoseal, NS) or fluoro-zinc-silicate glass (Caredyne Shield, CS), followed by an additional three days of demineralization. Dentin discs for three days of demineralization (de3) and six days of demineralization (de6) without the desensitizers were also prepared. The dentin discs after the experimental protocol were scanned using swept-source optical coherence tomography (SS-OCT) to image the cross-sectional (2D) view of the samples and evaluate the SS-OCT signal. The signal intensity profiles of SS-OCT from the region of interest of 300, 500, and 700 µm in depth were obtained to calculate the integrated signal intensity and signal attenuation coefficient. The morphological differences and remaining chemical elements of the dentin discs were also analyzed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. SS-OCT images of CS and NS groups showed no obvious differences between the groups. However, SS-OCT signal profiles for both the CS and NS groups showed smaller attenuation coefficients and larger integrated signal intensities than those of the de6 group. Reactional deposits of the desensitizers even after the additional three days of demineralization were observed on the dentin surface in NS group, whereas remnants containing Zn were detected within the dentinal tubules in CS group. Consequently, both CS and NS groups showed inhibition effects against the additional three days of demineralization in this study. Our findings demonstrate that SS-OCT signal analysis can be used to monitor the dentin demineralization and inhibition effects of desensitizers against dentin demineralization in vitro.

Highlights

Dentin hypersensitivity (DH) is a dental condition characterized by localized sharp pain arising in response to external stimuli, typically thermal, tactile, evaporative, osmotic, or chemical stress, without any other dental defects or disease [1,2,3,4,5,6]
On the rereconstructed gray-scale image, the dentin surface after six days of demineralization constructed gray-scale image, the dentin surface after six days of demineralization apappeared clearly distinct from the sound dentin with increased brightness
The images peared clearly distinct from the sound dentin with increased brightness

Summary

Introduction

Dentin hypersensitivity (DH) is a dental condition characterized by localized sharp pain arising in response to external stimuli, typically thermal, tactile, evaporative, osmotic, or chemical stress, without any other dental defects or disease [1,2,3,4,5,6]. Erosion has been considered the main etiological factor for DH, because it is capable of opening and enlarging the dentinal tubules to allow for fluid to flow through the tubules [9,10,11]. One of the main strategies for DH treatment involves depolarization of the nerve or occlusion of the dentinal tubules [12]. Several desensitizers have been introduced for treatment of DH to occlude dentinal tubules and reduce dentin permeability.

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