Article
3D Printed In Vitro Dentin Model to Investigate Occlusive
Agents against Tooth Sensitivity
Shiva Naseri
1,†
, Megan E. Cooke
2,†
, Derek H. Rosenzweig
2
and Maryam Tabrizian
1,
*
Citation: Naseri, S.; Cooke, M.E.;
Rosenzweig, D.H.; Tabrizian, M. 3D
Printed In Vitro Dentin Model to
Investigate Occlusive Agents against
Tooth Sensitivity. Materials 2021, 14,
7255. https://doi.org/10.3390/
ma14237255
Academic Editors: Mutlu Özcan and
Ludwig Cardon
Received: 5 October 2021
Accepted: 24 November 2021
Published: 27 November 2021
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4.0/).
1
Department of Biomedical Engineering, McGill University, Montreal, QC H3A 2B4, Canada;
shiva.naseri@mail.mcgill.ca
2
Department of Surgery, McGill University, Montreal, QC H3G 1A4, Canada;
megan.cooke@mail.mcgill.ca (M.E.C.); derek.rosenzweig@mcgill.ca (D.H.R.)
* Correspondence: maryam.tabrizian@mcgill.ca
† Shiva Naseri and Megan E. Cooke contributed equally to this work.
Abstract: Tooth sensitivity is a painful and very common problem. Often stimulated by consuming
hot, cold, sweet, or acidic foods, it is associated with exposed dentin microtubules that are open to
dental pulp. One common treatment for tooth hypersensitivity is the application of occlusive particles
to block dentin microtubules. The primary methodology currently used to test the penetration and
occlusion of particles into dentin pores relies upon dentin discs cut from extracted bovine/human
teeth. However, this method is limited due to low accessibility to the raw material. Thus, there
is a need for an
in vitro
dentin model to characterize the effectiveness of occlusive agents. Three-
dimensional printing technologies have emerged that make the printing of dentin-like structures
possible. This study sought to develop and print a biomaterial ink that mimicked the natural
composition and structure of dentin tubules. A formulation of type I collagen (Col), nanocrystalline
hydroxyapatite (HAp), and alginate (Alg) was found to be suitable for the 3D printing of scaffolds.
The performance of the 3D printed dentin model was compared to the natural dentin disk by
image analysis via scanning electron microscopy (SEM), both pre- and post-treatment with occlusive
microparticles, to evaluate the degree of dentinal tubule occlusion. The cytocompatibility of printed
scaffolds was also confirmed
in vitro
. This is a promising biomaterial system for the 3D printing of
dentin mimics.
Keywords: 3D printing; dentin; occlusive particles; tooth sensitivity
1. Introduction
Dentin contains thousands of open-ended microtubules to ensure its permeability.
This permeability is essential to support the physiology and reaction patterns of the pulp–
dentin organ. Nutrients and impulses are transported from the pulp via the odontoblast
process, while the contents of its tubules maintain the dentin as a vital tissue. When dentin
microtubules are exposed to the oral environment [
1
] through receding gums, loss of the
cementum, and smear layers and tooth wear [2], it results in hypersensitivity [3,4].
Dentin hypersensitivity is a very common dental problem characterized by short and
sharp pain. It arises in response to stimuli, typically thermal (hot or cold), evaporative,
tactile, osmotic (sweet or salty), chemical (acidic or basic), or electrical, with no effective
remedy [
5
,
6
]. Common short-term treatments include applying fluoride gels, rinses, or
varnishes that can be applied to sensitive areas of the teeth at regular intervals to help
strengthen the tooth, or tooth surface treatment with occluding agents [
7
,
8
]. A current
area of interest to reduce dentin sensitivity is decreasing tubule permeability through
occlusion [
9
]. A number of studies have shown that dentin sensitivity is reduced when the
dentinal tubules are occluded [10–12].
The current gold standard to determine the penetration and adhesion of occlusive
particles into dentin pores is to use dentin discs cut from extracted bovine/human teeth
Materials 2021, 14, 7255. https://doi.org/10.3390/ma14237255 https://www.mdpi.com/journal/materials
