Effect of Dentin Pretreatment with Dialdehyde Carboxymethyl Cellulose on Dentin Properties and Long-Term Adhesion

Objectives: The aim of this in vitro study was to evaluate the effect of pretreatment of dentin with different concentrations (0, 1%, 2.5% or 5%) of dialdehyde carboxymethyl cellulose (DCMC) on the biodegradation rates, mechanical properties of the dentin and long-term dentin bonding (mu TBS and nanoleakage).Methods: In all tests, specimens were designated to 4 groups: Control (without DCMC), DCMC1%, DCMC2.5% and DCMC5%. For the biodegradation evaluation, dentin beams (n = 5) were prepared (2x2x6mm), dehydrated, and demineralized. After, the beams were immersed in test solutions for 24h. After, the biodegradation rate was quantified by hydroxyproline assay. The nano-indentation technique was used to measure nanohardness and elastic modulus. 2 mm thick dentin slices (n = 5) were prepared. After dentin etching, the pretreatment solution (according to groups) was applied for 1 min, followed by drying with absorbent paper. After bonding procedure and restoration, the specimens were polished and the nanohardness and modulus of elasticity were evaluated. For mu TBS, the dentin of forty-eight teeth (n = 6) was etched and pretreated for 1 min according to groups, the adhesive system was applied, and resin composite buildups were constructed incrementally. Beams (1 mm2) were obtained and mu TBS was evaluated after 24h and 1 year of water storage. 2 beams of each tooth were separated for nanoleakage tests (after 24h and 1 year of water storage).Results: Control and DCMC1% presented higher biodegradation rates when compared to DCMC2.5% and DCMC5%. The nanohardness of dentin and hybrid layer was higher for DCMC1%, DCMC2.5% and DCMC5% when compared to Control. DCMC2.5 and DCMC5% increased the modulus of elasticity of hybrid layer, when compared to Control and DCMC1%. DCMC1%, DCMC2.5% and DCMC5% showed lower immediate mu TBS than Control, but they showed no decrease in mu TBS and nanoleakage after 1 year of storage. Control showed signif-icant decrease of mu TBS and significant increase of nanoleakage after aging.Conclusions: The use of DCMC as a dentin pretreatment decreased the biodegradation rate, improved the me-chanical properties of dentin, and preserved the long-term bond strength.