Browsing by Author "Hass, V."

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    Collagen cross-linkers on dentin bonding: Stability of the adhesive interfaces, degree of conversion of the adhesive, cytotoxicity and in situ MMP inhibition
    (2016) Hass, V.; Luque Martínez, Íssis Virginia; Gutierrez, M. F.; Moreira, C. G.; Gotti, V. B.; Feitosa, V. P.; Koller, G.; Otuki, M. F.; Loguercio, A. D.; Reis, A.
    Objective. To investigate the effect of collagen cross-links on the stability of adhesive properties, the degree of conversion within the hybrid layer, cytotoxicity and the inhibition potential of the MMPs' activity. Methods. The dentin surfaces of human molars were acid-etched and treated with primers containing: 6.5 wt% proanthocyanidin, UVA-activated 0.1 wt% riboflavin, 5 wt% glutaraldehyde and distilled water for 60s. Following, dentin was bonded with Adper Single Bond Plus and Tetric N-Bond; and restored with resin composite. The samples were sectioned into resin-dentin "sticks" and tested for microtensile bond strength (mu TBS) after immediate (IM) and 18-month (18 M) periods. Bonded sticks at each period were used to evaluate nanoleakage and the degree of conversion (DC) under micro-Raman spectroscopy. The enzimatic activity (P1L10 cross-linkers, P1L22 MMPs' activities) in the hybrid layer was evaluated under confocal microscopy. The culture cell (NIH 3T3 fibroblast cell line) and MTT assay were performed to transdentinal cytotoxicity evaluation. Data from all tests were submitted to appropriate statistical analysis (alpha = 0.05). Results. All cross-linking primers reduced the degradation of mu TBS compared with the control group after 18 M (p > 0.05). The DC was not affected (p > 0.213). The NL increased after 18 M for all experimental groups, except for proanthocyanidin with Single Bond Plus (p > 0.05). All of the cross-link agents reduced the MMPs' activity, although this inhibition was more pronounced by PA. The cytotoxicity assay revealed reduced cell viability only for glutaraldehyde (p < 0.001). Significance. Cross-linking primers used in clinically relevant minimized the time degradation of the mu TBS without jeopardizing the adhesive polymerization, as well as reduced the collagenolytic activity of MMPs. Glutaraldeyde reduced cell viability significantly and should be avoided for clinical use. (C) 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
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    Degradation of dentin-bonded interfaces treated with collagen cross-linking agents in a cariogenic oral environment: An in situ study
    (2016) Hass, V.; de Paula, A. M.; Parreiras, S.; Gutierrez, M. F.; Luque Martínez, Íssis Virginia; Matos, T. D.; Bandeca, M. C.; Loguercio, A. D.; Yao, X. M.; Wang, Y.; Reis, A.
    Objectives: To evaluate the effect of treatment using collagen cross-linking agents as primer on resin-dentin bond interfaces subjected to cariogenic oral environment (COE). Methods: Each of forty human teeth had two cavities (4 x 4 x 1.5 mm) prepared within enamel margins. These cavities were acid-etched and treated by the primers containing one of the following treatment agents (6.5% proanthocyanidins, 0.1% riboflavin-UVA activated light, 5% glutaraldehyde or distilled water as a control group). After that the cavities were bonded and restored with resin composite. One restoration for each tooth was tested immediately (IM) and another was included in an intra-oral palatal device that was placed in each mouth of ten adult volunteers for 14 days in COE. After 14 days, the teeth were removed and each restoration was sectioned to obtain a slice for Knoop microhardness (KHN) and resin-dentin bonded sticks for microtensile bond strength (mu TBS) and nanoleakage (NL) evaluation. Data were evaluated by two-way ANOVA and Tukey's tests (alpha = 0.05). Results: After 14 days in a COE, the KHN was reduced for all groups, except for the glutaraldehyde group; however, the proanthocyanidins group retained the highest KHN in IM and after COE (p < 0.05). The mu TBS was not reduced after COE for the proanthocyanidins and glutaraldehyde groups, however only the proanthocyanidins treatment did not increase the NL after COE (p > 0.05). Conclusion: The in situ study model seems to be a suitable short-term methodology to investigate the degradation of the bonding interfaces under a more realistic condition. Under COE, the proanthocyanidins and glutaraldehyde treatments produced stable interfaces that are worth further clinical investigation. (C) 2016 Elsevier Ltd. All rights reserved.
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    Five-year Effects of Chlorhexidine on the In Vitro Durability of Resin/Dentin Interfaces
    (2016) Loguercio, A. D.; Hass, V.; Gutierrez, M. F.; Luque Martínez, Íssis Virginia; Szezs, A.; Stanislawczuk, R.; Bandeca, M. C.
    Purpose: To evaluate the effect of an acid containing 2% chlorhexidine (Ac/CHX) or a 2% CHX aqueous solution (Aq/CHX) on the immediate and 5-year bonding properties of resin/dentin interfaces produced by two adhesives. The presence of CHX in these interfaces was also evaluated under micro-Raman spectroscopy. Materials and Methods: Forty-two molars were ground to expose a flat dentin surface. In the control group, the surfaces were etched with conventional phosphoric acid, and Prime&Bond NT (PB) and Adper Single Bond 2 (SB) were applied. In Ac/CHX, an acid containing 2% CHX was applied after adhesive application. In the Aq/CHX group, an aqueous solution of 2% CHX was applied for 60 s after etching. After placing the restoration, specimens were prepared and tested using the microtensile bond strength test (mu TBS, 0.5 mm/min) immediately or after 5 years. For nanoleakage (NL), specimens at each period were immersed in silver nitrate solution and examined by EDX-SEM. In addition, specimens at each period underwent examination for CHX using micro-Raman spectroscopy. Data were submitted to appropriate statistical analysis (alpha = 0.05). Results: After 5 years, NL was more pronounced in the control than in the Ac/CHX or Aq/CHX (p < 0.001). Significant reductions in the mu TBS were observed for all groups; however, they were more pronounced for the control (p < 0.001). CHX was still present in the hybrid layers Ac/CHX or Aq/CHX groups after 5 years. Conclusion: The use of a 2% chlorhexidine-containing acid or the application of an aqueous CHX primer may increase the long-term stability of resin/dentin interfaces.