Author(s):
Ribeiro, Ana 
; Rocha, L. A. ; Ariza, E. ; Celis, J. P.
Date: 2005
Persistent ID: http://hdl.handle.net/1822/5818
Origin: RepositóriUM - Universidade do Minho
Subject(s): Tribocorrosion; Dental implants
Description
The demand for metallic materials in medical and dental devices is large; metals
and alloys are widely used as biomedical materials and are indispensable in the medical
field. In particular, toughness, elasticity, rigidity, and, some times, electrical conductivity are essential properties for metallic materials used in medical devices. In
dentistry, titanium is used for restorations, orthodontic wires, and dental implants.
Materials implanted in the human body are intermittently stressed with loads,
which are repeated in a tremendous amount of cycles. During mastication, dental
implants are simultaneously subjected to corrosion by the oral environment and to the
sliding-wear process by bite forces. Dental wear can be attributed to mastication where
the teeth are worn by attrition and abrasion. The main aim of the present study was to
investigate the tribocorrosion behaviour of titanium grade 2 in reciprocating sliding
conditions in contact with artificial saliva solutions. Particular attention is given to the
relationship between mechanical damage and the electrochemical behaviour of the
material.
Sliding-corrosion experiments were performed using a reciprocating ball-on-flat
contact configuration and the open circuit potential was monitored during the test. Also
electrochemical impedance spectroscopy was used to obtain a more detailed description
of the corrosion mechanisms and to characterise the passive layer that forms on the titanium surface. To reproduce the oral environment around the dental implant, some
additives (citric acid, anodic, cathodic and organic inhibitors) were added to simple
artificial saliva constituted mainly by NaCl and KCl, and with a pH between 5 and 7. A
corundum ball was loaded on the top of the flat rectangular sample at a normal force of
10N. Linear peak-to-peak displacement amplitude of 3 mm at vibrating frequencies of 1
Hz was applied to the tribocorrosion system. The tests were performed for 11160
cycles. The surface roughness and topography of the titanium samples were evaluated prior to testing.
In relation to the friction profile, for all solutions, no significant differences were
observed. In fact, the aqueous environment used doesn’t have sufficient viscosity to
cause changes in the friction behavior. Regarding the weight loss results it is possible to conclude that titanium in artificial saliva solution with citric acid present the high
weight lost. Additionally, cathodic and organic inhibitors solutions exposed a higher
tendency for corrosion, forming an oxide passive film with lower protection characteristics.
