The hydrolytic stability of a pre-activated MPS silane (Monobond-S) and a 2-component 4-META/ γ-MPTS silane (Porcelain Liner M) to H 2O2-etched quartz fiber posts was investigated using a modeling approach. Composite build-ups around silanized posts were stored dry for 24 hours, stored in deionized water at 37°C for 24 hours, 1 week, 1 month or they were thermocycled. Sectioned specimens were prepared for microtensile bond testing and SEM examination; 4-META/γ-MPTS silane produced a rapid decline in bond strength after 1 week and 1 month of water storage and after thermocycling. This was not apparent in pre-activated MPS silane. SEM revealed debonding along the post-composite interfaces, which were coupled with 2-component silane. The use of a hydrophilic resin monomer (4-META) for on-demand hydrolysis of the γ-MPTS silane expedited interfacial water sorption and hydrolytic degradation, which may be prevented with alternative coupling strategies.
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