Effects Of Hybrid Coat Dentin Protective Film On Adhesive Properties Of Five Cements In Vitro

Objective:Dentin desensitizer (Hybrid Coat) can affect the bonding between dentin and adhesive cements.This in vitro study was to observe the microscopic character of the dentinal surface with the previous application of Hybrid Coat and analyze the degree of closed dentinal tubules after using Hybrid Coat.Besides, this study was to compare the differences of the shear strengths and the microleakage value of five cements to dentine surfaces between conbined with and without Hybrid Coat treatment.Further to provide the experimental basis in vitro and theoretical basis for the treatment with Hybrid Coat dentin protective film of the hypersensitive abutment teeth with vital pulp after teeth preparation.Methods:Freshly extracted human bicuspids were prepared for a standardized crown preparation.The Hybrid Coat dentin protective film was used on the prepared teeth.Observed the microscopic characteristic of the dentinal surface and cross section with the previous application of Hybrid Coat by using SEM.Individual castings were made from a base nickel-chromium alloy.Bonded these alloy castings to the teeth pretreated with Hybrid Coat with 5 different cements individually.Cementing agents included Zinc phosphate cements(ZPC), Zinc polycarboxylate cements(ZPCC), Glass ionomer cements(GIC), Resin-modified glass ionomer cements(RMGIC), Resin cements(RC).Measured the shear strength of different groups by universal testing machine.Nickel-chromium alloy crowns were manufactured for each prepared teeth with the previous application of Hybrid Coat and cemented with RMGIC and RC and measured microleakage by sliver-staining method.Analyzed by SPSS 17.0 statistics software.Results:1.The seal capability of the Hybrid Coat:the orifices of dentinal tubules were occluded completely and the hybrid layer was observed thickly in Hybrid coat samples under SEM, but the orifices of dentinal tubules were only occluded partly with smear layer in control group.2.The result of shear strength experiment:the control group of ZPC ZPCC and GIC showed the greater shear strength than the experimental group of ZPC+Hybrid Coat, ZPCC+Hybrid Coat and GIC+Hybrid Coat: ZPC (0.746±0.078MPa) and ZPC+Hybrid Coat (0.228±0.039MPa); ZPCC (12.363±2.160MPa) and ZPCC+Hybrid Coat (1.755±0.298MPa); GIC (5.284±0.715MPa) and GIC+Hybrid Coat (1.369±0.336MPa); the experimental group of RC+Hybrid Coat and RMGIC+Hybrid Coat showed the greater shear strength than the control group of RC and RMGIC:RMGIC (6.413±1.111MPa) and RMGIC+Hybrid Coat (8.812±1.728MPa); RC (8.309±1.139MPa) and RC+Hybrid Coat (13.309+2.152MPa).3.Microleakage experiment:the experimental group of RC+Hybrid Coat and RMGIC+Hybrid Coat showed the less microleakage than the control group of RC and RMGIC:RMGIC (2.05±0.14mm) and RMGIC+Hybrid Coat (1.32±0.08mm); RC (0.68±0.22mm) and RC+Hybrid Coat (0.33±0.14mm)Conclusions:1.Using Hybrid Coat can seal the dentinal tubule effectively and form hybrid layer thickly.2.The effect of Hybrid Coat on the bonding performance of cements associates with both component and bonding mechanisms.3.With RC and RMGIC, the use of Hybrid Coat significantly increases shear strength values.Contractively, the use of the hybrid coat decreases shear strength for ZPC, ZPCC and GIC evaluated.4.Using Hybrid Coat can degrade the microleakage value of RMGIC and RC.5.Hybrid Coat should be combined with RMGIC and RC as adhesive cements in clinic.