Significant Difference In Wear Research Articles

Comparative Study of Wear of Enamel Induced by Alternating and Simultaneous Combinations of Abrasion and Erosion in vitro

Two types of interaction of erosive and abrasive forces with human enamel were analysed in an in vitro study. To simulate toothbrushing or chewing after an acidic challenge, enamel specimens were eroded in 0.3% citric acid (pH 3.2), then brushed with or without silica abrasive. To simulate simultaneous erosion and abrasion, as would occur during chewing of abrasive acidic food, enamel specimens were abraded in a toothbrushing machine, with and without silica abrasive, while immersed in citric acid. Enamel wear was measured by profilometry. In both experiments the combination of erosion and abrasion resulted in significantly greater wear than erosion alone, but no significant differences in wear after brushing with or without abrasive were found. Simultaneous erosion and abrasion resulted in about 50% more wear than alternating erosion and abrasion. It is concluded that softened enamel is highly unstable and potentially easily removed by short and relatively gentle physical action. Chewing of acidic foods with some abrasive properties might cause enhanced tooth wear.

Physico-mechanical properties of a fast-set highly viscous GIC restorative.

The fast-setting reaction of 'fast-set' highly viscous glass-ionomer cements (GIC) may result in superior mechanical properties and good wear resistance as the material can theoretically achieve sufficient strength to resist masticatory loads within a shorter time. The aim of this study was to determine the hardness, strength (compressive and diametral tensile) and wear resistance of a 'fast-set' highly viscous GIC (Fuji IX GP Fast). Its regular set counterpart (Fuji IX GP) was used for comparison. The glass powders of the two cements were also characterized. Hardness testing [Vickers' hardness number (VHN)] was performed with a digital hardness tester (load=50 g; dwell time=30 s) and compressive/diametral tensile strength testing (MPa) was conducted based upon British Standards specification for GICs (BS6039, 1981). Wear testing was conducted using a reciprocal compression-sliding wear instrumentation at 20 MPa contact stress against SS304 counter-bodies with distilled water as lubricant. All specimens were immersed in distilled water at 37 degrees C and tested 24 h after start of mixing. Further mechanical tests (hardness and strength) were conducted with specimens stored for 1 week in distilled water at 37 degrees C. The glass powders were characterized using laser particle sizing, standard electron microscope (SEM) and energy dispressure X-ray (EDX) analysis. Results were analysed using multiple analysis of variance (manova) and independent samples t-test at significance level 0.05. No significant difference in hardness, compressive and diametral tensile strength was observed between Fuji IX GP and Fuji IX GP Fast at 1 day. There was also no significant difference in wear at all cyclic intervals. Although the difference in strength was not significant between the two cements at 1 week, Fuji IX GP Fast was significantly harder than Fuji IX GP. Particle size of both cements ranged from 0.3 to 200 microm. The mean particle sizes were, however, different and were 13.43 and 7.13 microm for Fuji IX GP and Fuji IX GP Fast, respectively. Fuji IX GP Fast offers no other advantage over Fuji IX GP with the exception of improved hardness. Besides being harder, the fast-set highly viscous GIC restorative offers no other physico-mechanical advantage over its regular set counterpart.

Impacting-sliding Wear Test with Enamel of a Highly Filled Hybrid Resin for Crown and Bridge.

New types of composite resins for crown and bridge were recently developed and put on the market. One of them is a highly filled hybrid resin (ESTENIA, Kuraray) including 92 wt% (82 vol%) of ceramic particles. It is claimed that the resin much improved in hardness and strength is available for posterior crown and bridge. The present study examined the wear behavior of this resin when opposed by tooth enamel by means of impacting-sliding wear test, comparing with three kinds of materials for posterior use, porcelain, Au-Ag-Pd alloy and restorative composite resin. A hemispherical upper specimen and a flat lower specimen were prepared with each of the material and tooth. The upper specimen made of each material dropped and slid on the lower specimen made of tooth, or vice versa, for 10,000 times under a given load of 500 gf in artificial saliva. The Knoop hardness number was the largest in porcelain and the next in tooth enamel, Au-Ag-Pd alloy, hybrid resin and restorative resin, in that order ; however, the wear resistance was not dependent on the hardness in this test. The combination of porcelain and tooth showed significantly severe wear in both the specimens. The observation of the worn surface aspects revealed that the superficial cracking of them might induce their wears. There were no significant differences in wear among Au-Ag-Pd alloy-enamel, restorative resin-enamel and tooth-tooth. The highly filled hybrid resin exhibited the mixed wearing modes of porcelain and restorative resin. The combination of highly filled hybrid resin and tooth showed larger wears than tooth-tooth but significantly smaller than porcelain-tooth, and the hybrid resin seemed to be more favorable than porcelain for esthetic posterior crown and bridge.

Investigation of human enamel wear against four dental ceramics and gold

Objectives. This in vitro study compared the wear of enamel against aluminous porcelain, bonded porcelain, low fusing hydrothermal ceramic, feldspathic machinable ceramic, and cast gold. Methods. Fifty pairs of tooth-material specimens were tested in a dental wear machine, under a standard load (40 N), rate (80 cycles min −1) and for 25 000 cycles in distilled water. The amount of wear was determined by measuring the height loss of the tooth, and the depth of wear track of the restorative materials. Results. There was a significant difference in wear among the groups for both enamel and materials ( p < 0.001). Follow-up comparisons (95% CI significance level) showed that gold caused significantly less enamel wear than all ceramics tested. The amount of enamel wear in the aluminous and bonded porcelain groups was significantly higher than with the hydrothermal and machinable ceramic groups. There was no significant difference between the amount of enamel wear produced by the aluminous and bonded porcelains nor between that produced by the hydrothermal and machinable ceramics. Furthermore, the wear of the aluminous and bonded porcelains was significantly greater than that of the hydrothermal ceramic, the machinable ceramic and gold. No significant difference in wear was found between aluminous and bonded porcelains, hydrothermal and machinable ceramics, or between machinable ceramic and gold. However, the hydrothermal ceramic had significantly greater wear than gold. Conclusions. It was concluded that the hydrothermal and the machinable ceramics were significantly less abrasive and more resistant to wear than the conventional aluminous and bonded porcelains. Gold was the least abrasive material and most resistant to wear, although the difference in wear between the machinable ceramic and gold was not statistically significant.

Wear in uncemented porous and cemented polyethylene sockets

We used radiostereometric analysis to compare wear rates between uncemented porous sockets and cemented all-polyethylene sockets in a series of 102 hips randomised for either a Harris-Galante or a Charnley cup. Wear was evaluated in 95 hips at a mean of five years (2 to 7). All hips had a cemented, 22 mm head mono-bloc Charnley stem. The mean annual wear rate was 0.09 mm in the Charnley sockets and 0.10 mm in the Harris-Galante sockets, with no statistically significant differences in wear, migration or rotation. We conclude that, up to five years, the wear characteristics of the modular and porous Harris-Galante socket resemble that of the Charnley socket.

Effect of an adhesive primer on the integrity of occlusal veneer-metal interface and wear of composite resin veneered restorations

This study examines the influence of a metal-resin bonding agent on the wear rate of composite resin veneer. The specimens were prepared with a silver-based casting alloy and a light-cured composite veneering material. After application of repeated loading through a three-body wear testing device, the amount of wear was measured. The results showed no significant difference in wear between bonded and nonbonded specimens on the 1.5 mm areas of the veneer-metal interface. However, the bonded specimens exhibited significantly lower wear values at the veneer-metal interface. The use of an adhesive primer effectively enhanced the integrity of the occlusal veneer-metal junction.

The Clinical Evaluation of Heat-Treated Composite Resin Inlays

Laboratory research indicates the physical properties of composite resin used for posterior restorations can be significantly increased if a secondary dry heat treatment of the material was accomplished. This study investigated the clinical performance of a heat-treated composite resin inlay, using both the direct and indirect methods of clinical evaluation. Contrary to laboratory results, no significant differences in wear could be measured between conventional light-cured inlays and those with secondary dry heat treatment. Other clinical advantages of the heat-treated inlays were observed.

The Wear of Polymers Sliding on Polymeric Films Deposited on Rough Surfaces

The single-pass, transfer wear of LDPE, PVC, and PCTFE was studied as a function of the roughness of the steel counterface, and the presence or absence of a polymeric coating. A 50 nm thick film of poly(chloro-p-xylylene) was formed on the steel in a pyrolytic-vapor-deposition process. The results showed that LDPE had lower friction and wear on the coated surface than on the uncoated surface. There was no significant difference in wear or friction as a function of surface coating for PVC and PCTFE. The results were explained by considering the deformation characteristics of the polymeric coating and the three polymer sliders and the modification of the topography by the polymeric coating.

Wear properties of cast vs plasma-sprayed Laves intermetallic alloys

Cast and plasma-sprayed surfaces of the same composition were prepared containing a substantial amount of a Laves intermetallic phase. Other compositions, all containing metal carbides, were prepared by plasma spraying, detonation-gun deposition, casting, and powder metallurgy. The Alpha LFW-1 wear test was used to compare wear properties of these surfaces in both room air and a nonlubricating liquid. No significant difference in wear and surface damage was evident between the cast and plasma-sprayed intermetallic wear surfaces. The performance of surfaces containing the intermetallic phase were equivalent to, or in most cases superior to, those whose hardness was due to metal carbides.