Effect of Different Osmotic Stimuli on Fluid Flow Before and After Self-etching Adhesive Application

Purpose: To determine the in vitro dentinal fluid movement produced by various osmotic stimuli, and evaluate fluid movement across human dentin in response to the application of various osmotic stimuli before and after the application of self-etching adhesive (Clearfil S3 Bond). Materials and Methods: The experiments were carried out on 10 extracted premolars. Each tooth was cut transversely below to the cementoenamel junction with a diamond disk and water coolant. Dentin was exposed at the tip of the buccal cusp by cutting a cavity and was etched with acid. The osmotic stimuli were solutions of saturated CaCl2, sugar syrup, chocolate, and sweet Thai dessert, used as osmotic test solutions, randomly applied to dentin. The fluid flow through dentin obtained after 15 s of application of each osmotic stimulus was measured before and after bonding with Clearfil S3 Bond single-dose. Results: Before bonding procedures, CaCl2 produced peak rates of fluid flow that were significantly higher (p 0.001), when compared with normal saline, sugar syrup, chocolate, and sweet Thai dessert. During the applications of all osmotic stimuli, the amount of fluid movement across resin-bonded dentin was significantly lower than that without adhesives. There were no significant differences of fluid shifts across resin-bonded dentin obtained during the application of any osmotic stimuli. Conclusion: It appears that different osmotic stimuli produced different rates of outward fluid flow through dentin. Clearfil S3 Bond produced similar significant reductions of fluid movement in response to osmotic stimulation, irrespective of the chemical composition, or the osmotic pressure of stimuli. Keywords: osmotic stimuli, fluid flow through dentin, self-etching adhesive, dentin permeability, human teeth