Use of dimethyl sulfoxide (DMSO) to optimize adhesive interface: analysis of its effectiveness on the mechanical and biological properties in dentin bonding

• Ano de defesa: 2021
• Autor(a) principal: Zabeu, Giovanna Speranza
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Adesivos dentinários; Camada híbrida; Dentin; Dentin bonding agents; Dentina; Enzyme inhibitors; Hybrid layer; Inibidores enzimáticos
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/25/25148/tde-07022022-113825/

The vulnerability of the bonding interface occurs because of the degradation of hybrid layer due to the presence of water and proteolytic enzymes, which interferes on the longevity of bonding restorations. Therefore, this work investigated the mechanism of the solvent dimethylsulfoxide (DMSO) on mechanical and biological properties of this interface, through the degree of conversion, microtensile bond strength, gelatin and in situ zymography. In this purpose, the work was divided in two parts: the first evaluated the mechanical properties (degree of conversion and microtensile bond strength) and the second tested the biological properties (gelatin and in situ zymography). The experimental design of the study involved three factors: dentin bonding systems (DBS) in five levels (Adper Scotchbond Multipurpose [MP], Adper Single Bond 2 [SB], Clearfil SE Bond [CSE], Adper Single Bond Universal [SU] - conventional modes [ER] and self-etching [SE]), dentin pretreatment in two levels (control water [C], DMSO [D] in different concentrations, depending on the test performed) and time in three levels (initial 24hours, 6 months and 30 months). In article 1, the degree of conversion of the DBSs associated with different concentrations of DMSO (0%, 1%, 2%, 5% and 10%) was evaluated by the Fourier Transformed Infrared Spectroscopy (FTIR), beyond the bond strength on dentin pretreated passively with 1% DMSO for 30 seconds, by microtensile test, followed by fracture mode analysis. The results showed that DMSO increased the stability of the DBSs after 30 months. For MP, SB and SU under ER and SE modes, DMSO treatment increased bond strength values in the initial period, while for CSE, values were maintained. After 30 months, SU for both modes and MP had a reduction of the bond strength values, even they still were higher compared to the control group. In article 2, the comparison of the enzymatic activity of DBSs associated with DMSO was made by gelatin and in situ zymographies. In gelatin zymography, the activity of purified MMP-2 and MMP-9 enzymes pre-incubated with different concentrations of DMSO (0%, 0.5%, 1%, 2%, 5% and 10%) were evaluated in order to verify whether DMSO has a direct effect on the inhibition of proteolytic enzymes. Then, in situ zymography was performed using dentin pretreated passively with 1% DMSO and 2% CHX for 30 seconds. The tooth-resin slices were evaluated using laser confocal scanning microscopy and the images were quantified at Image J software. Gelatin zymography showed no enzyme inhibition, regardless DMSO concentration. For in situ zymography, pretreatments did not affect initial conditions. After 6 months, there was an increase in activity for MP and SB, using both solutions and only DMSO, respectively. CSE and SU-SE showed a stabilized gelatinolytic pattern independent of the factors. For SU-ER, both pretreatments showed similar lower fluorescence compared to control. The 30-month evaluation indicates the susceptibility to degradation for the etch-and-rinse systems. The results of this study suggest that after 30 months, DMSO can be promissory depending on the ingredientes and mode of action of the dentin bonding systems. Its effect may be mostly related to its interaction with hydrolytic degradation, rather than potential on inhibition attributed to the enzymes.