RESUMO
Objective: To investigate the effects of three different types of dentin protective membranes (HyC, SBU and S3) on dentin adhesive properties. Methods: Fresh isolated molar teeth were collected, and smooth dentin surface was obtained after embedding, cutting and polishing. In the control group, dentin protective membrane was not applied, while the remaining three groups were coated with three different types of dentin protective membranes, and the preformed resin prosthesis was cemented with resin cement. A strip dentin-resin sample with a cross-sectional area of 0.9 mm×0.9 mm was obtained by a precision cutting machine. The tensile force was tested at the loading speed of 0.5 mm/min with a universal testing machine until the dentin-resin strip was broken. The maximum tensile force during the loading process was automatically recorded by the computer, and the microstructure and fracture mode of the section were observed by a scanning electron microscope. Results: After coating dentin protective membranes, the tensile strength of each experimental group was significantly increased compared with that of the control group (P<0.05), and the tensile strength of group HyC was significantly smaller than that of group SBU and group S3 (P<0.05). The tensile fracture mode shown by microstructure observation was mainly interfacial failure. Conclusion: Different types of dentin protective membranes can increase the adhesive properties between dentin and resin prosthesis. SBU and S3 can improve the adhesion strength more significantly than HyC.
RESUMO
STATEMENT OF PROBLEM: Titanium nitride(TiN) coatings are the most general and popular coating method and used to improve the properties of metallic surface for industrial PURPOSEs. When TiN coating applied to the abutment screw, frictional resistance would be reduced, as a results, the greater preload and prevention of the screw loosening could be expected. PURPOSE: The purpose of this study was to investigate mechanical properties of TiN coated film of various coating thickness on the titanium alloy surface and to evaluate proper coating thickness. MATERIAL AND METHOD: 95 Titanium alloy (Ti-6Al-4V) discs of 15 mm in diameter and 3 mm in thickness were prepared for TiN coating and divided into 7 groups in this study. Accoding to coating deposition time (CDT) with TiN by using Arc ion plating, were divided into 7 groups : Group A (CDT 30min), Group B (CDT 60min), Group C (CDT 90min), Group D (CDT 120min), Group E (CDT 150min), Group F(CDT 180min) and Group G (no CDT) as a control group. TiN coating surface was observed with Atomic Force Microscope(AFM), field emission scanning electron microscopy(FE-SEM) and examined with scratch tester, wear tester. Result: 1. Coating thickness for each coated group was increased in proportion to coating deposition time. 2. Surface of all coated groups except Group A was homogeneous and smooth. However, surface of none coated Group G had scratch. 3. Adhesion strength for each coated group was increased in proportion to coating deposition time. 4. Wear resistance for each coated group was increased in proportion to coating deposition time. 5. Surface roughness in Group A, B, C was increased in proportion to coating deposition time. But, surface roughness in Group D, E, F was showed decreased tendency in proportion to coating deposition time. CONCLUSION: According to coating deposition time, mechanical properties of TiN coated film were changed. It was considered that 120 minutes coating deposition time (1.32micrometer in coating thickness) is necessary.