Tribological behaviour of unveneered and veneered lithium disilicate dental material

authors	Figueiredo-Pina, CG; Patas, N; Canhoto, J; Claudio, R; Olhero, SM; Serro, AP; Ferro, AC; Guedes, M
nationality	International
journal	JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
author keywords	Sliding wear; Biotribology; Lithium disilicate glass-ceramic; Fluorapatite veneer; Teeth; Surface charge; Wettability
keywords	GLASS-CERAMICS; WEAR BEHAVIOR; TOOTH ENAMEL; RESTORATION; FRICTION
abstract	The friction and wear behaviour of a lithium disilicate dental ceramic against natural dental enamel is studied, including the effect of the presence of a fluorapatite veneering upon the tribological properties of the material. The tribological behaviour was assessed using reciprocating pin-on-plate test configuration, at pH 3.and pH 7. The surface energy of the plates was determined, as well as the zeta potential of fluorapatite, lithium disilicate and enamel particles in artificial saliva. It was found that the friction and wear behaviour of the tested enamel/plate material tribocouples is less severe in unveneered plates. Initial surface roughness of the plate does not affect wear results. However the topography of the resulting wear track affects the corresponding wear loss: a smoother final wear track is associated with lower wear. The surface topography of the wear track, and thus the tribological performance of the tested materials, is very sensitive to the pH of the sliding solution. This is because the dissolution trend, wettability and surface charge of the used materials are pH dependent. Overall friction and wear are higher under basic pH conditions, especially when plates are veneered. A wear model is proposed that correlates the effect of the described parameters with the observed tribological behaviour at pH 7. Attained results show that fluorapatite coating of lithium disilicate dental crowns affects tooth/crown wear behaviour, resulting in increased wear of both the artificial crown and the opposing natural teeth. Coating should therefore be avoided in occlusal crown surfaces. (C) 2015 Elsevier Ltd. All rights reserved.
publisher	ELSEVIER SCIENCE BV
issn	1751-6161
year published	2016
volume	53
beginning page	226
ending page	238
digital object identifier (doi)	10.1016/j.jmbbm.2015.08.007
web of science category	Engineering, Biomedical; Materials Science, Biomaterials
subject category	Engineering; Materials Science
unique article identifier	WOS:000366226500021