The effect of TiSiN interlayers on the bond strength of ceramic to NiCr and CoCr alloys

High bonding between the NiCr or CoCr alloys and the ceramic layer is essential for the clinical success of dental prostheses restorations. Aiming to enhance the bond strength between metal and dental ceramics in prosthetic restorations, TiSiN coatings were deposited as interlayers. The coatings were deposited on NiCr and CoCr dental alloys by using the cathodic arc technique at various substrate bias voltage values and characterized in terms of elemental composition, crystalline structure, mechanical properties, surface roughness and contact angle. The bond strength of the metal ceramic system, with and without TiSiN interlayers, was evaluated by using a three-point bending test. The coatings consisted of nanocrystalline solid solutions (grain sizes of 3.6-4.3 nm) with a face-centered cubic structure. The film hardness, ranging from approximately 21-38 GPa, was observed to increase with increasing substrate bias, irrespective of the substrate type. The best adhesion values (critical loads of similar to 54 N) were obtained on both substrates for coatings deposited at of -100 V bias voltage. The deposition of the TiSiN coatings determined the roughness decrease of both NiCr and CoCr coated alloys. The contact angle measurements indicated a hydrophobic character for the films deposited at bias voltages ranging from -50 to -150 V and a hydrophilic character at a bias of -200 V. The results indicated that TiSiN coatings improved the bond strength of NiCr ceramic systems. Based on these results an increase of the clinical service life of the dental restorations having a TiSiN interlayer between the metallic support and the ceramic layer is expected. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.