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Severe Wear (severe + wear)
Selected AbstractsAnalyzing the etiology of an extremely worn dentitionJOURNAL OF PROSTHODONTICS, Issue 4 2001Ronald G. Verrett DDS Patients requiring extensive restorative care frequently exhibit significant loss of tooth structure. Specific clinical findings in an extremely worn dentition may vary widely and are often confusing. Severe wear can result from a mechanical cause, a chemical cause, or a combination of causes. The location of the wear, the accompanying symptoms and signs, and information gained from the patient interview are essential components in determining the etiology. A diagnostic decision tree facilitates a systematic analysis and diagnosis of dental wear. [source] Detection of improvement in the masticatory function from old to new removable partial dentures using mixing ability testJOURNAL OF ORAL REHABILITATION, Issue 9 2005A. ASAKAWA summary, The aim of this study was to determine the sensitivity of the Mixing Ability Test to detect improvement of masticatory function in subjects on transition from old to new removable partial dentures. Thirty-two subjects (seven males, 25 females, mean age 65·0 years) with distal extension partially edentulous area in mandible and/or maxilla participated in the study. The following reasons were presented for replacing the old removable partial dentures with new ones: fracture and/or poor fitness of retainers, extraction of abutment teeth, poor fitness of denture base, severe wear of artificial teeth and request for metal base dentures. Masticatory function with old and new removable partial dentures after an adaptation period (mean 27·4 weeks) was evaluated by the Mixing Ability Test. Subjects were asked to masticate five two-coloured wax cubes with each removable partial denture. Mixing Ability Index was obtained from the colour mixture and shape of the masticated cubes. Wilcoxon signed-rank test was used to test the difference of Mixing Ability Indexes between old and new removable partial dentures. The mixing ability indexes with new removable partial dentures (mean ± s.d.: 0·70 ± 0·68) was significantly higher (P < 0·001) than those with old removable partial dentures (,0·11 ± 1·13). The results suggest that the Mixing Ability Test was capable of detecting improvement in masticatory function with new removable partial dentures. [source] The influence of oxygen on the friction and wear behaviour of a copper,steel couple under electric currentLUBRICATION SCIENCE, Issue 1 2004A. Bouchoucha Abstract The tribological behaviour of a copper,steel couple similar to those in electrified railways has been studied as a function of mechanical, electrical, and environmental parameters. The experimental results obtained in an oxygen atmosphere show that this factor has a major influence on the wear behaviour. While there was a reduction in the average coefficient of friction compared to in argon, under oxygen there was twice the wear found under air, and six times that found under argon. In the absence of an electric current, the nature of the wear was essentially mild adhesive. However, with an electric current at the interface, fluctuations, particularly at high intensities, were recorded in both the coefficient of friction and the electrical contact resistance, and there was severe wear. Discussion of the results is based on examination of the wear surfaces and analysis of the phenomena observed during sliding contact. [source] Verschleißmechanismen bei moderater und extremer GrenzreibungMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 10-11 2004M. Scherge wear mechanisms; continuous wear measurement; surface analysis Abstract Mit einem Stift-Scheibe-Tribometer wurden für das System Stahlstift/Stahlscheibe Versuche durchgeführt, die drastisch unterschiedliche Verschleißraten zur Folge hatten. Durch Wahl der Normalkraft wurde die Energiedissipation so eingestellt, dass im ersten Versuch Verschleißraten in der Größenordnung von Nanometern pro Stunde erreicht wurden, während im zweiten Versuch Mikrometer pro Stunde erzielt wurden. Die Proben wurden nach dem Experiment hinsichtlich Struktur und chemischer Zusammensetzung analysiert. Im Bereich der kleinen Verschleißraten dominierten plastisches Fließen und mechanische Vermischung während die hohen Verschleißraten mit starker Topographieänderung und Oxidation einher gingen. Wear mechanisms at moderate and extreme friction conditions Using a pin-on-disk tribometer drastically different wear rates were obtained in experiments running a steel pin against a steel disk. By tuning the normal force the energy dissipation was varied resulting in either mild wear in the range of nanometers per hour or severe wear with a wear rate of micrometers per hour. After the tribological tests the samples were analyzed with respect to structure and chemical composition. Whereas small wear rates are accompanied by plastic flow and mechanical intermixing, severe wear results in significant topography changes and oxidation. [source] Variation in dental wear and tooth loss among known-aged, older ring-tailed lemurs (Lemur catta): a comparison between wild and captive individualsAMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2010Frank P. Cuozzo Abstract Tooth wear is generally an age-related phenomenon, often assumed to occur at similar rates within populations of primates and other mammals, and has been suggested as a correlate of reduced offspring survival among wild lemurs. Few long-term wild studies have combined detailed study of primate behavior and ecology with dental analyses. Here, we present data on dental wear and tooth loss in older (>10 years old) wild and captive ring-tailed lemurs (Lemur catta). Among older ring-tailed lemurs at the Beza Mahafaly Special Reserve (BMSR), Madagascar (n=6), the percentage of severe dental wear and tooth loss ranges from 6 to 50%. Among these six individuals, the oldest (19 years old) exhibits the second lowest frequency of tooth loss (14%). The majority of captive lemurs at the Indianapolis Zoo (n=7) are older than the oldest BMSR lemur, yet display significantly less overall tooth wear for 19 of 36 tooth positions, with only two individuals exhibiting antemortem tooth loss. Among the captive lemurs, only one lemur (a nearly 29 year old male) has lost more than one tooth. This individual is only missing anterior teeth, in contrast to lemurs at BMSR, where the majority of lost teeth are postcanine teeth associated with processing specific fallback foods. Postcanine teeth also show significantly more overall wear at BMSR than in the captive sample. At BMSR, degree of severe wear and tooth loss varies in same aged, older individuals, likely reflecting differences in microhabitat, and thus the availability and use of different foods. This pattern becomes apparent before "old age," as seen in individuals as young as 7 years. Among the four "older" female lemurs at BMSR, severe wear and/or tooth loss do not predict offspring survival. Am. J. Primatol. 72:1026,1037, 2010. © 2010 Wiley-Liss, Inc. [source] | ||||||||||