Clinical Evaluation and Laboratory Wear- Testing Methods - Dental Biotribology - page 39

Fig. 2.1 Dental wear test confi gurations [ 29 ]
devices, have been used for many years. Although such a unidirectional sliding test
mode for simulation is far from a real mastication process, they are a very simple
way to evaluate the wear behavior of dental materials and have been utilized
until now.
DeLong and Douglas [ 25 ] developed the artifi cial mouth concept, which allowed
natural teeth to be loaded in a manner that simulates physiological movement. The
integration of two closed mechanical loops was used to produce a force-movement
cycle in order to simulate the mastication process. However, in this machine, only
one sample can be tested at a time, which made the evaluation of a spastically rele-
vant sample group very time-consuming. A computer-controlled chewing simulator
was presented by Krejcl et al. [ 26 ], and six samples could be tested at the same time.
In 1999, a more complete dual-axis chewing simulator in which eight samples could
be investigated simultaneously was developed by Kerm et al. [ 27 ]; the three-
dimensional masticatory loading curve was precisely controlled by two computer-
controlled stepper motors.
In order to simulate tooth cleaning, sliding and reciprocating wear tests with a
contact of various standard toothbrushes against a glass specimen were performed
under toothpaste (abrasive particles) conditions. The particles' evolution at the
interface was visualized by an optical apparatus, and the particles' trapping behav-
ior was analyzed as function of different mechanical parameters. The above wear-
testing rigs have been summarized by Dwyer-Joyce [ 28 , 29 ]. Figure 2.1 shows some