Two-body Wear Test Research Articles

Wear performance of substructure ceramics and veneering porcelains

Aim The aim of this in vitro study was to compare the two-body wear resistance of substructure zirconia and veneering porcelain versus steatite and human enamel antagonists, respectively. Materials and methods Two-body wear tests were performed in a chewing simulator with steatite and enamel antagonists (enamel cusps). A pin-on-block design with a vertical load of 50 N for 1.2 × 10 5 cycles; ( f = 1.6 Hz; lateral movement: 1 mm, mouth opening: 2 mm) was used for the wear test. For quantification of the wear resistance, wear tests were performed with standardized steatite spheres. Human enamel was used as a reference. Five zirconia ceramics and four veneering porcelains were investigated. One zirconia ceramic was tested with superficial glaze, which was applied after polishing or sandblasting, respectively. Surface roughness R a (SP6, Perthen-Feinprüf, G) and wear depth were determined using a 3D-Profilometer (Laserscan 3D, Willytec, G). SEM (Quanta FEG 400, FEI, USA) pictures were used for evaluating wear performance of both, ceramics and antagonists. Results No wear was found for zirconia substructures. Veneering porcelain provided wear traces between 186.1 ± 33.2 μm and 232.9 ± 66.9 μm (steatite antagonist) and 90.6 ± 3.5 μm and 123.9 ± 50.7 μm (enamel). Wear of the steatite antagonists varied between 0.812 ± 0.256 mm 2 and 1.360 ± 0.321 mm 2 for zirconia and 1.708 ± 0.275 mm 2 and 2.568 ± 0.827 mm 2 for porcelain. Enamel generally showed wear, cracks or even fractures at the ridge, regardless whether opposed by zirconia or porcelain/glaze. Enamel was polished, when opposed to zirconia, or plowed, provoked and grinded, when opposed to porcelain/glaze. Conclusion The results of the wear test with steatite or enamel antagonists indicated no measurable wear on zirconia surfaces. Porcelain showed higher wear than zirconia, but comparable or lower wear than an enamel reference. Antagonistic wear against zirconia was found to be lower than wear against porcelain.

In vitro wear resistance, hardness and elastic modulus of artificial denture teet

In this study, the wear resistance, hardness, elastic modulus, and the correlations between them of artificial denture teeth at the sub-enamel layer were examined. Four types of tested artificial denture teeth consisted of 3 conventional acrylic resin teeth (Cosmo HXL, Major Dent, and Yamahachi FX), 1 high cross-linked acrylic resin teeth (Trubyte Bioform IPN), 2 composite resin teeth (SR Orthosit PE, and Yamahachi PX), and 1 porcelain teeth (ACE Teeth). The two-body wear test was performed using a custom made pin on disc apparatus. Volume and weight loss were measured. Hardness and elastic modulus were also assessed by using a nanoindentation system. The results suggested wear resistance varied among the denture tooth materials. Wear resistance of high cross-linked acrylic resin teeth was the lowest. A definite relation between wear resistance and mechanical properties of materials could not be found in this study.

Wear characteristics between prosthodontic hybrid composite resin teeth and various metal teeth using two-body wear test

Wear characteristics between prosthodontic hybrid composite resin teeth and various metal teeth using two-body wear test

Mutual wear evaluation of resin composites when opposing enamel and dentin

Mutual wear rates of resin composites and both superficial and deep layers of enamel and dentin were investigated by means of an in vitro wear test. Occlusal surfaces of extracted molars were ground flat to respective layers of enamel and dentin. Hemispherical-shaped styli (n = 8) made of microfilled and microhybrid composites were placed perpendicular to the finished tooth surface (600 grit) in the presence of tap water, and a two-body wear test (75 N load and 1.2 Hz) was performed for 100,000 cycles. The wear depths on both tooth and composite specimens were determined, and the data were statistically analyzed by two-way ANOVA and Boneferroni test (p < 0.05). The values of deep and superficial dentin specimens against Esthet-X (530.2 +/- 213.0 microm and 717.4 +/- 309.6 microm) were significantly greater than those against Epic-TMPT (34.1 +/- 17.6 microm and 29.3 +/- 10.8 microm). The values of Esthet-X against dentin were the smallest (2.4-2.6 microm), followed by those of the same material against enamel (5.5-6.1 microm), and those of Epic-TMPT against enamel (7.2-7.9 microm). It was concluded that the wear rates of dentin varied with the type of composite used while those of enamel showed the consistency.

Wear of resin denture teeth by two-body contact

The objective of this study was to examine the two-body wear resistance of nine different resin denture teeth and one experimental material. The two-body wear test was performed in a chewing simulator with an antagonistic Al(2)O(3) ball under an axial load of 40 N for 100,000 cycles. In each test series, an enamel sample was included as a reference. The wear was determined with an optical 3D surface profilometer. For statistical evaluation, SPSS for Windows was used. The samples of Artiplus (18.7-SD 21.0) and e-Ha (21.2-SD 15.1) showed the lowest volumetric wear (in mm(3)x10(-3)) after 100,000 cycles. The difference from the other materials tested, except NC Veracia Posterior, was statistically significant (p=0.001-0.037). SR-Postaris-DCL (55.0-SD 6.8), SR-Orthosit-PE (61.1-SD 12.4) and Vitapan (72.1-SD 15.9) exhibited medium-sized wear values with low dispersion, whereas Orthognat (80.1-SD 31.6), Premium 8 (84.6-SD 31.4), NC Veracia Posterior (87.0-SD 52.7), SR-Orthotyp-PE (114.6-SD 28.0) and Trubyte Portrait (123.0-SD 45.6) showed high wear values with great variations. Statistically provable differences were found between SR-Orthotyp-PE and SR-Postaris-DCL (p=0.019) and also between SR-Orthotyp-PE and SR-Orthosit-PE (p=0.031). For enamel, a medium-sized wear value of 66.1-SD 76.8 was determined. The denture teeth examined showed differences in two-body wear resistance. The wear values determined were in some cases higher and in others lower than those of natural enamel. A definite connection between the wear resistance and the chemical composition of the materials could not be found in this investigation.

レーザー照射によるチタンの表面改質が耐摩耗性に及ぼす影響

Severe wear of cast commercial pure (CP) titanium teeth was observed in a clinical survey. This study evaluated the wear resistance of cast CP titanium and titanium alloy teeth after the surface was modified using laser technology. Teeth patterns were duplicated from artificial first molars (Livdent FB30, GC, Japan). All teeth specimens were cast with CP Ti grade 3 (T-Alloy H, GC) and Ti-6Al-7Nb (T-Alloy Tough, GC). After the occlusal surface was blasted with Al(2)O(3), the occlusal contact points were modified using a laser (Neo laser L, Girrbach, Germany) at the following irradiation conditions (voltage: 260 V; pulse: 7 ms; focus: 1.5 mm). These parameters were determined by preliminary study. As a control, Type IV gold alloy (PGA-3, Ishifuku, Japan) was also cast conventionally. Both maxillary and mandibular teeth were worn using an in vitro two-body wear testing apparatus that simulated chewing function (60 strokes/min; grinding distance: 2 mm under flowing water). Wear resistance was assessed as volume loss (mm(3)) at 5 kgf (grinding force) after 50,000 strokes. The results (n=5) were analyzed by ANOVA/Scheffé's test (alpha=0.05). The gold alloy showed the best wear resistance of all the metals tested. Of all the titanium specimens tested, the modified surface indicated significantly greater wear resistance than did conventional titanium teeth without surface modification (p<0.05). Wear resistance was increased by modification of the surface using a laser. If severe wear of titanium teeth was observed clinically, little wear occurred when the occlusal facets were irradiated using a laser.

Wear Resistance of Magnetic Fe-Pt Alloy Teeth

Purpose: Fe-Pt alloys have magnetic properties and can be cast using a dental casting machine. However, no studies have ever been conducted to examine the wear of Fe-Pt alloys. This study evaluated the in vitro wear resistance of magnetic Fe-Pt alloy teeth.Materials and Methods: Maxillary and mandibular tooth patterns were duplicated from artificial first molars (Livdent FB30, GC, Japan) and cast from a custom-made Fe-Pt ingots (Fe-39.5 at % Pt-0.75 at % Nb) using a high-frequency centrifugal casting machine (Jelenko Eagle, Jelenko, NY, USA). The cast teeth were vacuum-enclosed in quartz-glass tubes, solution-treated at 1,325°C for 45 min., and then quenched in ice water. Subsequently, the teeth were aged at 600°C for 5 hours to acquire hard magnetic properties. As controls, Au-Ag-Pd alloy (Castwell MC, GC), Au-Pt alloy (PGA-3, Ishifuku, Japan) and Co-Cr alloy (Wisil, Austenal, Germany) were also prepared by conventional casting. The wear of the teeth (both maxillary and mandibular) was measured using an in vitro two-body wear testing apparatus that simulated chewing function (60 strokes/min., grinding distance: 2 mm under flowing water). Wear resistance was assessed as volume loss (mm3) at 49 N (grinding force) after 50,000 strokes. The results (n=5) were analyzed by ANOVA/Fisher's test (α=0.05).Results: The wear resistance [Mean (SD)] of each alloy was: Au-Pt [0.55 (0.14)], Au-Ag-Pd [0.40 (0.05)], Fe-Pt [0.02 (0.03)], and Co-Cr [0.04 (0.01)]. Fe-Pt alloy had the least wear although there were no significant differences compared to Co-Cr alloy (p>0.05). The Au-Pt alloy had the worst wear resistance of all the metals tested (p<0.05).Conclusion: Based on the results of this study, Fe-Pt alloy should wear very little when used for both maxillary and mandibular teeth.

Abrasive Wear Behavior of Heat‐Treated ABC‐Silicon Carbide

Hot‐pressed silicon carbide, containing aluminum, boron, and carbon additives (ABC‐SiC), was subjected to three‐body and two‐body wear testing using diamond abrasives over a range of sizes. In general, the wear resistance of ABC‐SiC, with suitable heat treatment, was superior to that of commercial SiC. When the fine‐scale (3 μm) diamond abrasives were used, it was found that thermal annealing at 1300°C increased the resistance to three‐body wear by a factor of almost three, and two‐body wear by a factor of almost two, compared with as‐hot‐pressed samples. Higher annealing temperatures, however, led to a decline in wear resistance from its highest value. Similar behavior was seen for 1300°C‐annealed samples subjected to 15 μm diamond abrasive, although higher‐temperature annealing at 1500°–1600°C enhanced the wear resistance again. When coarse abrasives (72 μm) were used, the wear resistance progressively increased with increased annealing temperature from ∼1000° to 1600°C. Corresponding transmission and scanning electron microscopy studies indicated that, whereas transgranular, conchoidal cracking was dominant in the mild abrasive wear with fine‐scale (3 μm) abrasives, intergranular cracking and subsequent grain pullout was far more predominant in the more severe abrasive wear with coarse abrasives. Because the hardness and indentation toughness were barely altered during thermal treatment, the observed wear behavior was attributed mainly to the thermally induced microstructural changes, including the crystallization of glassy grain‐boundary films, the possible strengthening of the boundaries due to the enhancement of the aluminum, and the formation of aluminum‐rich, coherent nanoscale precipitates in the matrix grains above 1300°C.

Influence of filler loading on the two-body wear of a dental composite.

The purpose of the study was to explore the fundamental wear behaviour of a dental composite with different filler loadings under two-body wear conditions. The parent resin and filler components were mixed according to different weight ratios to produce experimental composites with filler loadings ranging from 20 to 87.5% by weight. A two-body wear test was conducted on the experimental composites using a wear-testing machine. The machine was designed to simulate the impact of the direct cyclic masticatory loading that occurs in the occlusal contact area in vivo. The results showed that there was little increase in the rate of wear with filler loadings below 60 wt%, but a sharp increase between 80 and 87.5 wt% in filler loading. Wide striations and bulk loss of material were apparent on the wear surfaces at higher filler loadings. Coefficients of friction increased with filler loading and followed the increase in rate of wear loss closely. It was concluded that, under two-body wear conditions, addition of high levels of filler particles into the resin matrix could reduce the wear resistance of dental composites. This finding may help when designing future dental composites for use in particular clinical settings.

Characterization of Fe-Cr-B based coatings produced by HVOF and PTA processes

Two Fe-Cr-B based gas atomized powders, Armacor M and 16, were thermally sprayed on a low carbon steel substrate, using the HVOF (High Velocity Oxygen Fuel) process. Armacor M was also weld-surfaced with the PTA (Plasma Transferred Arc) process. The resultant deposits were subsequently characterized, using X-ray diffraction, scanning electron microscopy, and microhardness measurement. The effects of heat treatment were also studied for HVOF-sprayed coatings. The wear performance of the coatings was investigated by two-body abrasive wear tests. The results of microstructural analysis of as-sprayed deposits revealed oxide and boride phases such as Fe3O4 and Cr1.65F0.35B0.96 in an α matrix for the HVOF-sprayed Armacor 16 coating, and only the boride phases (Cr1.65F0.35B0.96 and Cr2B) in an α matrix for the HVOFsprayed Armacor M coating. PTA weld-surfaced Armacor M coating contains needle-type long precipitates of Cr2B) and Cr1.65F0.35B0.96, in the α matrix. The hardness of the HVOF-sprayed Armacor 16 coating after heat treatment was substantially less than that of the as-sprayed coating due to the phase transformation from α to γ phase. Heat treatments of the HVOF-sprayed Armacor M coating did not produce changes in phase and its hardness decreased as compared to that of the as-sprayed coating. While HVOF-sprayed and PTA weld-surfaced Armacor M coatings have the same hardness, the latter shows better abrasive wear resistance because of the size and orientation of its boride phases. The broadening of the XRD patterns and the increase in hardness after wear testing suggest that the transformation from the crystalline to the amorphous structure occurred on the uppermost layer during wear testing.

Wear characteristics in a two-body wear test

Objectives. A previous report compared spherical steatite (ceramic enamel substitute) abraders with those of natural enamel in a two-body wear test. The wear rates and coefficients of friction of the two abraders against various composites and an amalgam were well correlated although the wear rates were slightly higher with steatite. This report investigates the characteristics of the worn abrader and specimen surfaces. Methods. Scanning electron microscopy and laser profilometry were used. Results. Similar wear characteristics were found for the two types of abraders. Adhesive wear was evident for the amalgam, Dispersalloy (Johnson & Johnson), and the heat/pressure-cured microfill composite, Isosit (Ivoclar-Vivadent). Abrasion was seen with the hybrid composite, Occlusin (ICI), and, to a lesser extent, the microfill composite, Heliomolar (Ivoclar-Vivadent). The appearance of the worn small particle hybrid composite, Brilliant Dentin (Coltène), suggested that fatigue and delamination were involved. Laser profilometry showed that the hybrid composites caused much greater wear to the abraders than either the microfill composite or amalgam. The Ra values of the worn abraders and specimens were similar, suggesting conformal contact between them and endorsing the well controlled conditions of the wear test. Significance. The results of this and other publications suggest that steatite can be used as an alternative to enamel in performing two-body wear tests on dental composites. This should help significantly in materials evaluation and development.

In vitro two-body wear of inlay-onlay composite resin restoratives

Inlay-onlay composite resin restorations have been introduced to the profession as alternatives to amalgam and direct composite resins. Two-body wear testing was performed on three inlay-onlay resins and one direct composite resin using a machine designed to produce sliding wear. The composite resins were opposed by human enamel, type III gold alloy, and porcelain. Of the investigated materials, the homogeneously microfilled inlay-onlay material showed significantly less wear. The direct composite resin showed significantly the greatest wear. The hybrid inlay-onlay resins showed intermediate wear. The hybrid inlay-onlay resins and the direct composite (small particle, heavily filled) resin created wear tracks in the opposing surfaces while the homogeneous microfill inlay-onlay resin did not. The depth of the observed wear tracks in the opposing surfaces was sufficiently substantial to warrant further investigation into the wear of materials that oppose composite resin restorations.