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Mechanical stability and proteolytic activity of the resin-dentin bond produced using the cross-linked dry technique

Grant number: 17/03927-9
Support type:Scholarships in Brazil - Master
Effective date (Start): June 01, 2017
Effective date (End): March 31, 2019
Field of knowledge:Health Sciences - Dentistry - Dental Materials
Cooperation agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
Principal Investigator:Josimeri Hebling Costa
Grantee:Mariana Citta
Home Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

Water has an antagonistic role in the process of adhesion to dentin. While the presence of water is important during the earliest phases to keep the interfibrillar spaces for the infiltration of adhesive monomers, it negatively restricts the infiltration of hydrophobic monomers, promotes phase separation and interferes with solvent evaporation. Moreover, water is a key element in collagen breakdown by dentin proteases such as matrix metalloproteinases (MMP) and cysteine cathepsins. Therefore, the aim of this study will be to evaluate the stability and proteolytic activity of resin-dentin bonds produced by the application of adhesive systems with different hydrophilicity on a cross-linker-biomodified and dehydrated dentin. One hundred and twenty-eight human molars will be collected and cut to obtain flat dentin surfaces. The teeth will be initially divided into four groups (n=32) according to the cross-linker agent: 5% proanthocyanidin (PA); 5% glutaraldehyde (GD); Gluma Desensitizer (GL); and distilled water (control). The solutions will be applied for 60 seconds on the phosphoric acid etched dentin followed by rinsing with distilled water. After, each group will be randomly subdivided as a function of the dentin hydration condition. In half of the teeth (n=16) the dentin will be kept moist by blot drying the excess water with absorbent paper. In the remaining 16 teeth, etched dentin will be dehydrated by 30 seconds with air blasts. Once concluded the treatment of the dentin, groups will be again subdivided in two equal groups of 8 teeth. Two experimental adhesive systems will be prepared in such way that it will be possible to know their solubility parameters. One adhesive will be more hydrophobic while the other more hydrophilic. Both adhesives will be applied in two consecutive layers with solvent evaporation being performed for each layer separately. Then, they will be photo-activated for 20 seconds. Composite resin cylinders will be built up by applying three 1 mm-thick increments, each one photo-activated for 20 seconds. Twenty-four hours after the adhesive procedures and storage at 37 oC, immersed in distilled water, the teeth will be cut to produce specimens (0,81 mm2 of cross-sectional area) for the microtensile test. Specimens cut from the same tooth will be randomly divided into 2 sets. Each set of specimens will be tested immediately or 12 months after aging in saliva-like solution. Sixty-four additional teeth will be divided and prepared as described previously. These teeth will be cut into 0.5 mm-thick slices for silver nitrate nanoleakage and in situ zymography analyses, also immediately after the production of the resin-dentin bond or after 12 months of aging. Statistical tests will be selected based on the factors of the study ("cross-linker", "dentin hydration condition" and "aging period") and on the response variable "bond strength". The tests will be repeated for each adhesive system to identify the repetition of phenomena. It will also be considered data distribution and groups homoscedasticity. All statistical inferences will be taken at the 5% level of significance. Nanoleakage and proteolytic activity will be analyzed descriptively. (AU)

Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
CITTA, Mariana. Estabilidade mecânica e atividade proteolítica de interfaces produzidas com a técnica de adesão seca à dentina biomodificada. 2019. 70 f. Master's Dissertation - Universidade Estadual Paulista "Júlio de Mesquita Filho" Faculdade de Odontologia (Campus de Araraquara)..

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