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Response of pulp cell to the application of acrolein and its effect on the mechanical stability of resin-dentin bons

Grant number: 18/14105-2
Support type:Scholarships in Brazil - Master
Effective date (Start): November 01, 2018
Effective date (End): February 29, 2020
Field of knowledge:Health Sciences - Dentistry - Dental Materials
Cooperation agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
Principal researcher:Josimeri Hebling Costa
Grantee:Lays Nóbrega Gomes
Home Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

The hybrid layer is the weakest link of the resin-dentin bond despite its major role in the retention of the restorative material and dentin sealing. The endurance of the hybrid layer against the hydrolytic and enzymatic degradation processes is directly dependent of the individual resistance of its components, polymer and collagen. Therefore, the aims of this study are: (1) to evaluate the cytotoxicity of acrolein on pulp cells and (2) its effect as a collagen cross-linker on the mechanical stability of the resin-dentin bond. To answer the first objective, 0.4 mm-thick dentin discs (n=54) will be obtained from sound human molars and individually fit in artificial pulp chambers (APCs). MDPC-23 odontoblast-like cells will be seeded on the pulpal surface of the discs, using DMEM. The occlusal dentin will be etched with phosphoric acid for 15 seconds, followed by rinsing and blot drying. The following solutions will be applied on the etched dentin (n=9): deionized water (negative control), 0.005% acrolein, 0.01% acrolein, 0.02% acrolein, 5% glutaraldehyde or 3% hydrogen peroxidase (positive control). After 60 seconds of contact with the dentin, the excess will be removed with absorbent paper and the APCs will be kept in an incubator for 24 hours. The cellular viability of the MDPC-23 attached to the pulpal surface of the discs will be accessed using alamarBlue, and the conditioned medium (extract) will be collected and applied on new MDPC-23 and HDPCs (human dental pulp cells) previously grown in culture plates. These cells will be analyzed as to cellular viability (alamarBlue), alkaline phosphatase activity (thymolftalein assay), mineralized matrix formation (Alizarin red), analysis of the oxidative stress, and gene expression of ALPL, DSPP, DMP1, MMP2, MMP9 e IL1b (RT-qPCR). To answer the second aim of the study, thirty flat dentin surfaces produced on sound human teeth will be assigned according to the dentin treatment (n=10): deionized water (control), acrolein (in a concentration to be selected from the biological tests), or 5% glutaraldehyde. The solutions will be applied on the phosphoric acid etched dentin, kept for 60 seconds, and rinsed with deionized water. Single Bond 2 will be applied on a moist dentin surface followed by the built-up of a composite resin block. Beam specimens with a sectional area of 0.81 mm2 will be cut from each tooth and randomly divided into 2 groups. In one group the specimens will be submitted to the microtensile test immediately after being cut. In the other group the specimens will be tested after 6 months of storage in saliva-like solution. Followed the microtensile test, the failures will be classified in adhesive, mixed, cohesive in dentin or cohesive in resin. Dataset of each response variable will be checked with regards to the adherence to the normal curve and the variation factors as to homoscedasticity. Statistical tests will be selected based on the fulfillment of these prerequisites. The level of significance of 5% will be set for all inferential statistics.

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Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
. 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. 2020. Master's Dissertation - Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araraquara Araraquara.

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