Properties of dental resins submitted to pH catalysed hydrolysis

Autor(es)

Cilli, Renato ^[1] ; Pereira, Jose Carlos ^[2] ; Prakki, Anuradha ^[3]

Afiliação do(s) autor(es)

^[1] Univ Fortaleza, Fac Dent, Dept Dent Mat & Operat Dent, Fortaleza, Ceara - Brazil

^[2] Univ Sao Paulo, Bauru Dent Sch, Dept Operat Dent Endodont & Dent Mat, BR-05508 Sao Paulo - Brazil

^[3] Univ Toronto, Fac Dent, Dept Clin Sci Restorat, Toronto, ON M5G 1G6 - Canada

• Tipo de documento: Artigo Científico
• Fonte: Journal of Dentistry; v. 40, n. 12, p. 1144-1150, DEC 2012.
• Citações Web of Science: 17

Resumo

Objectives: This study evaluated the surface microhardness (SM) and roughness (SR) alterations of dental resins submitted to pH catalysed degradation regimens. Methods: Thirty discs of each TPH Spectrum (Dentsply), Z100 (3M-ESPE), or an unfilled experimental bis-GMA/TEGDMA resin were fabricated, totaling 90 specimens. Each specimen was polymerized for 40 s, finished, polished, and individually stored in deionized water at 37 degrees C for 7 days. Specimens were randomly assigned to the following pH solutions: 1.0, 6.9 or 13, and for SM or SR evaluations (n = 5). Baseline Knoop-hardness of each specimen was obtained by the arithmetic mean of five random micro-indentations. For SR, mean baseline values were obtained by five random surface tracings (R-a). Specimens were then soaked in one of the following storage media at 37 degrees C: (1) 0.1 M, pH 1.0 HCl, (2) 0.1 N, pH 13.0 NaOCl, and (3) deionized water (pH 6.9). Solutions were replaced daily. Repeated SM and SR measurements were performed at the 3-, 7- and 14-day storage time intervals. For each test and resin, data were analysed by two-way ANOVA followed by Tukey's test (alpha = 0.05). Results: There was significant decrease in SM and increase in SR values of composites after storage in alkaline medium. TPH and Z100 presented similar behaviour for SM and SR after immersion in the different media, whereas unfilled resin values showed no significant change. Conclusion: Hydrolytic degradation of resin composites seems to begin with the silanized inorganic particles and therefore depend on their composition. Significance: To accelerate composite hydrolysis and produce quick in vitro microstructural damage, alkaline medium appears to be more suitable than acidic medium. Contemporary resin composite properties seem to withstand neutral and acidic oral environments tolerably well. (C) 2012 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 08/06170-7 - Estabilidade da matriz dentinária através do tratamento com diferentes agentes de ligação cruzada, e seus efeitos na promoção de adesão em dentina.
• Beneficiário: Renato Cilli
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado