Response of pulp cells to dentin biomodification with acrolein and effect on the ultimate tensile strength of the dentin matrix and the resin-dentin bond

Author(s)

Lays Nobrega Gomes

• Document type: Master's Dissertation
• Press: Araraquara. 2020-05-07.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araraquara
• Defense date: 2020-02-18
• Advisor: Josimeri Hebling

Abstract

Objective: To investigate the transdentinal cytotoxicity of acrolein (ACR) on pulp cells, as well as the ultimate tensile strength (UTS) of the dentin matrix, and the strength of resin-dentin bonds after dentin collagen biomodification with this cross-linker. Methods: Dentin disks (0.4 mm thick) were cut from sound human molars and adapted in artificial pulp chambers. MDPC-23 were seeded on the pulpal side of the disks and the occlusal surface was etched with phosphoric acid for 15s. The etched dentin was treated with (n=9): deionized water (control), 0.02%, 0.01%, 0.005% ACR, 5% glutaraldehyde (GD), or 3% hydrogen peroxide. After 60s, the surface was rinsed, and the chambers were incubated for 24h. The viability of MDPC-23 cells seeded on the disk was assessed (alamarBlue) and the extracts were applied on new MDPC-23 and HDPCs (human dental pulp cells) seeded in culture plates. After 24h, the viability of the cells was investigated as well as the activity of alkaline phosphatase, presence of mineralized nodules (Alizarin red) and ALPL, DSPP, MMP2, MMP9 and IL1b gene expression (qPCR). Additional twenty-five human molars were sectioned to obtain dentin specimens (n=50) which were completely demineralized in 10% phosphoric acid for 24h. The specimens were treated for 60s with: water, 0.02%, 0.01%, 0.005% ACR or 5% GD, and then submitted to a mechanical test to determine the UBS. Finally, flat dentin surfaces prepared in 40 human molars were etched with phosphoric acid and treated for 60s with water, 0.01%, 0.005% ACR, or 5% GD, followed by rinsing. Single Bond 2 was applied, and a resin block was buildup. After 24h, the teeth were cut to produce beam specimens (0.81mm2) submitted to the microtensile test and nanoleakage analysis. Datasets were analyzed by ANOVA and Tukey tests (α=0.05). Results: Significant viability reduction was seen for MDPC-23 seeded on the dentin disks for 0.02%, 0.01% ACR, GD and hydrogen peroxide; however, except for the later, the highest reduction was 21% for GD. Conversely, for both cell lines in contact with the extracts, ACR did not interfere with cell viability, ALP activity, and the presence of mineralized nodules. IL1b was the only gene expression not affected by the treatments. Overall, the expression of a lower number of genes was affected by 0.005% ACR in comparison to the other treatments. The UBS of the dentin matrix was significantly improved after the treatment 0.02% ACR and 5% GD. However, dentin biomodification with these cross-linkers did not interfere with the immediate resin-dentin bond strength. Presence of nanoleakage in hybrid layers produced on dentin treated with ACR was comparable to dentin treated with water (control). Conclusion: The application of ACR on etched dentin was not toxic to odontoblast-like and pulp cells, however, only 0.02% ACR was able to increase the mechanical resistance of dentin matrices. Lastly, collagen biomodification using ACR did not interfere with the immediate bond strength to dentin. (AU)

• FAPESP's process: 18/14105-2 - Response of pulp cell to the application of acrolein and its effect on the mechanical stability of resin-dentin bons
• Grantee: Lays Nóbrega Gomes
• Support type: Scholarships in Brazil - Master