Tribological behaviour of unveneered and veneered lithium disilicate dental material.
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.
Department of Mechanical Engineering, Setúbal School of Technology, Instituto Politécnico de Setúbal, Setúbal, Portugal; CeFEMA, Instituto Superior Técnico, ULisboa, Lisboa, Portugal. Electronic address: celio.pina@estsetubal.ips.pt.
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Figueiredo-Pina
Setúbal School of Technology, Instituto Politécnico de Setúbal, Setúbal, Portugal.
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Patas
Setúbal School of Technology, Instituto Politécnico de Setúbal, Setúbal, Portugal.
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Canhoto
Department of Mechanical Engineering, Setúbal School of Technology, Instituto Politécnico de Setúbal, Setúbal, Portugal; IDMEC, Instituto Superior Técnico, ULisboa, Lisboa, Portugal.
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Cláudio
Department of Materials and Ceramics Engineering, CICECO, University of Aveiro, Aveiro, Portugal.
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Olhero
Instituto Superior de Ciências da Saúde Egas Moniz, Quinta da Granja, Caparica, Portugal; CQE, Instituto Superior Técnico, ULisboa, Lisboa, Portugal.
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Serro
Department of Mechanical Engineering, Instituto Superior Técnico, ULisboa, Lisboa, Portugal; CeFEMA, Instituto Superior Técnico, ULisboa, Lisboa, Portugal.
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Ferro
Department of Mechanical Engineering, Setúbal School of Technology, Instituto Politécnico de Setúbal, Setúbal, Portugal; CeFEMA, Instituto Superior Técnico, ULisboa, Lisboa, Portugal.
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Guedes
D001031:Apatites; D003776:Dental Porcelain; D003801:Dental Veneers; D017276:Friction; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D055595:Mechanical Phenomena; D013314:Stress, Mechanical; D013499:Surface Properties; D014070:Tooth; D017155:Wettability
D001031:Apatites; C493120:lithia disilicate; D003776:Dental Porcelain; C025105:fluorapatite
Biotribology; Fluorapatite veneer; Lithium disilicate glass-ceramic; Sliding wear; Surface charge; Teeth; Wettability.