Wear of Composites by Abrasives of Varying Hardness

The relationship between the wear of three composite resins and the hardness of the abrasive was studied by a two-body abrasion test. The wear rates of the composites increased linearly with abrasive hardness from 530 to 2080 KHN. Measurement of the slope of the wear rate versus abrasive hardness over this range provided a sensitive method for ranking the composites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68031/2/10.1177_00220345790580031201.pd

In vitro Wear of Microfilled and Visible Light-cured Composites

Wear of microfilled composites, a visible light-cured composite, and a conventional composite were characterized by two-body abrasion and single-pass sliding. There were differences in abrasion rates among the materials. Tangential forces, wear track widths, and surface failure modes were different among materials. Wear characteristics are combinations of these properties.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67083/2/10.1177_00220345790580111301.pd

Wear of Fluorapatite Single Crystals : V. Influence of Environment on Frictional Behavior and Surface Failure

The influence of environment on the frictional behavior and surface failure of fluorapatite single crystals was evaluated for sliding in air, water, and dimethylformamide. The coefficient of friction was independent of environment. The ductile-to-brittle transition, however, occurred at a lower load in water than in air.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68110/2/10.1177_00220345730520050501.pd

Frictional Behavior and Surface Failure of Human Enamel

The frictional behavior and surface failure of human enamel under sliding in water was examined. A large plowing component of friction was observed. For normal loads of up to 1kg, ductile behavior of the wear scar was apparent. Intermittent cracks were obrerved that appeared to propagate around the enamel rods.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67266/2/10.1177_00220345730520063001.pd

Erosion of Composite Resins

The surface degradation of composite resins caused by accelerated aging was studied. Accelerated aging for 900 hours caused erosion of the resin matrices and exposure of filler particles. Differences in surface profiles after aging suggest that the materials eroded at different rates. Accelerated aging may model erosive wear of composites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67987/2/10.1177_00220345800590051101.pd

Wear of Fluorapatite Single Crystals: III. Classification of Surface Failure

Modes of surface failure observed for natural fluorapatite single crystals under sliding were classified and related to wear and frictional behavior. The basal surfaces exhibited brittle or ductile failure depending on the combination of load and slider design. The transition occurred at penetrations of 0.3 to 0.5 μm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67122/2/10.1177_00220345720510026101.pd

Parameters that Affect the Color of Direct Restorative Resins

The effects of thickness, background color, specular reflection, and surface roughness on the color of five commercial restorative resins were studied by reflection spectrophotometry. As thickness increased, values of luminous reflectance and excitation purity increased for a black background but decreased for a white background. Opacity increased dramatically as thickness increased from 1.3 to 3.9 mm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67249/2/10.1177_00220345780570090701.pd

Frictional Behavior and Surface Failure of Acrylic Denture Teeth

The wear characteristics of acrylic denture teeth were investigated under single- and double-pass sliding. The response of acrylic teeth to sliding was that of a relatively ductile material. The wear characteristics were affected similarly by environments of water and saliva. The "enamel" surfaces showed more resistance to penetration and were less susceptible to surface damage than the "dentin" surfaces. The effect of the second pass was to increase track width and cause a more severe mode of surface failure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67388/2/10.1177_00220345810600051001.pd

Penetration of Commercial and Dental Waxes

Penetration of commercial and dental waxes was studied. Measurements indicated that resistance of paraffin and dental inlay waxes to penetration was closely related to the temperature at which solid-solid transformations occurred. Annealed waxes were more resistant to penetration than unannealed waxes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67386/2/10.1177_00220345740530023701.pd

Thermal Expansion of Composite Resins and Sealants

Linear thermal coefficients of expansion (α) of seven commercial composite resins and four pit and fissure sealants were determined between 0 and 60°C on a thermomechanical analyzer. The thermal expansion curves obtained were nonlinear. Values of α ranged from 26.5 to 39.6 × 10-6 °/C for the composite and from 70.9 to 93.7 x 10-6/°C for the sealants.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67284/2/10.1177_00220345790580020701.pd