A simple thermal cycling device for testing dental materials.
Explore the source record for details and available documents.
Adhesiveness↗
SEARCH · PubMed Health
Results for “Materials Testing”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Experimental studies of acute anterior cruciate ligament injury and repair.
Ten dogs and six rhesus monkeys underwent transection and repair of the anterior cruciate ligament. One-half of the procedures involved the femoral end, the other half involved the tibial end of the ligament. Seven of the 10 canine and all of the primate ligaments, that had been transected and repaired, did heal. Functional and clinical instability was demonstrable in all repaired knees. The monkeys developed fewer degenerative changes with more grossly normal appearing ligaments after the repairs than did the dogs. Failure testing on an Instron materials testing machine revealed maximum strength of the repaired ligaments to be 10.4% for the repairs at the femoral end and 2.0% for repairs at the tibial ends in dogs when compared with the contralateral control knees. In monkeys the femoral repairs were 46.8% and the tibial repairs were 62.6% of the control knees. Inadequate immobilization and early stress were believed to be principal causes of the poorer results in dogs. The observations in monkeys support the suggestion that injured anterior cruciate ligaments that can be repaired, should be repaired.
Animals↗
A new foam for support of the physically handicapped.
This article is intended to inform professionals in the fields of rehabilitation medicine and biomedical engineering of some of the more significant properities of Temper Foam, a new foam for support of the physically handicapped. The unique properties of this foam are explained in terms of its microstructure, illustrated by scanning electron micrographs and by mechanical tests using an Instron Materials Testing machine. Fourteen non-ambulatory patients with Duchenne muscular dystrophy are using this foam in custom-fitted contoured support systems. Normally, these children show increasing signs of discomfort and skin breakdown due to their inability to alternate areas of weight bearing and high local pressure such as the ischial tuberosities. In our support systems lined with Temper Foam these problems have completely dissappeared. We find that Temper Foam types T-36, T-38 and -41 are ideally suited for patients weighing up to 35 kg. T-41 may be used for patients weighing up to 70 kg.
Bedding and Linens↗
[Methods of expressive evidence of orthopoxviral infections tested on material from vaccinial skin lesions of rabbits (author's transl)].
Explore the source record for details and available documents.
Animals↗
[Comparative endurance tests of materials used for fixation of the trochanteric fractures].
Explore the source record for details and available documents.
Bone Nails↗
Angiostrongylus cantonensis: infectivity of first stage larvae in the presence of rat fecal materials as tested by the in vitro cultivation technique.
Explore the source record for details and available documents.
Animals↗
Analytic study of the Tadoma method: discrimination ability of untrained observers.
This study reports the ability of two observers with normal-hearing and sight to discriminate pairs of speech elements through the Tadoma method of speechreading. The observers were blindfolded and exposed to masking noise to eliminate visual and auditory cues. They placed their right hand over the speaker's face and neck so that the thumb rested lightly on the lips and the fingers fanned out over the cheek and neck. The discrimination tests were conducted using an ABX procedure. Average discrimination scores for the five types of test materials used in the ABX tests were 87% on W-22 words, 83% on Modified Rhyme Test words, 70% on vowels, 77% on CV and VC nonsense syllables, and 71% on consonant clusters. In all of the ABX tests, the inexperienced observers performed at least as well as the experienced Tadoma user studied by Norton, et al (1977). This finding indicates that the basic tactile sensitivity of inexperienced observers is comparable to that of an experienced deaf-blind Tadoma user.
Cues↗
Microimmunodiffusion test for diagnosis of ovine progressive pneumonia.
Two microimmunodiffusion tests (MIDT) for detection and measurement of ovine progressive pneumonia antibody are described. Substrates of various salt concentrations and pH were used to determine the optimal conditions for the tests. In comparisons between two MIDT and one macroimmunodiffusion test, sera from cull ewes were used. The MIDT require less reagents and were more responsive than the macroimmunodiffusion test. After extended incubation of the test materials, results in all three tests were comparable.
Animals↗
Enamel bonding plastic materials in modifying the form of abutment teeth for the better functioning of partial prostheses.
The potential uses of enamel bonding sealants and composite filling materials in increasing the retentive form of abutment teeth and covering the preparations for the occlusal supports of partial prostheses were studied in laboratory conditions. The materials tested were Nuva and Concise sealants and composite resins. Extracted permanent human molars, premolars and canines were inserted into acrylic blocks, two teeth in each block. An unretentive clasp framework was made on every test block. A retention prominence was built up separately of sealants and of composite materials occlusally to the tip of each clasp arm. The bond strength and wear resistance of the materials was tested in a device designed for this study. The bond of the prominences was very good, only two out of 114 prominences loosened. The retention gained with prominences was, on average, 18 N measured by the force needed for removal. The decrease in the total retention of the four clasp arms was measured by the force needed to remove the clasp framework. The total retention of the prominences made of Nuva and Concise sealants after 5000 removals was 53 and 50% of the original, when long, flexible clasp arms were used. The corresponding figures for composite resins were 56 and 59%. Short rigid clasp arms caused a distinctly faster abrasion. The prominences made of sealants, in particular, were abraded rapidly, one-fifth of retention being left after 3000 removals.
Composite Resins↗
[Technological studies on high pressure polymerization of dental plastic materials].
The author in his present paper reports a program of comparative materials testing of which the purpose was to assess the value of positive pressure polymerization of thermosets. This particular program required polymerization temperature measurements. K-value determinations, and cone indentation hardness tests to be made on samples of plastic material polymerized under positive liquid or steam pressure and in cuvets, respectively, the conditions of polymerization being those which are used in actual practice. The results obtained indicated a favorable influence of positive liquid pressure polymerization on the final hardness of the plastic material.
Dental Materials↗
[Mutual relations between plastic materials and bacteria (author's transl)].
The complex problems of microbiological degradation of synthetic plastics and a fairly wide variety of 62 testing materials, belonging to 14 major groups of plastics, are described. Adaequate and reliable testing techniques had to be devised. Drawing on the experiences of H. Braun, 1930, and of Bushnell and Haas, 1941, as to the metabolism of bacteria and the utilization of certain hydrocarbons by microorganisms, and previous research work by A. Schwartz in Berlin, 1959-60, on microbial corrosion of plastics, methods of laboratory testing were developed. The bacteriological technique was based on selection of aerobic microorganisms, which were, by starvation, adapted to use the plastic materials as their only carbon source; foreign carbon sources had to be strictly eliminated; emphasis was laid on proper, double control cultures. The test organisms involved included P. aeruginosa and fluorescens strains, also a certain species of Candida, and mixtures of soil, sewage and garbage organisms grown on exposed plastic surfaces. By means of series of passages the selective adaptation and conservation of these organisms was continued up to 4 1/2 years. An anaerobic adaptation method for Desulfovibrio desulfuricans was developed and used successfully. After preliminary experimentation (Soil burial, sewage and garbage exposure tests) in the laboratory as well as in the open, a large scale Field testing programme under realistic and to some extent extreme conditions was implemented: Nine different plastic materials comprising eight plain high polymer plastics and for comparison one synthetic Cellulose derivate, together with glass control samples, were exposed in twelve different sewage, garbage, and soil media over a period of 3 months to 2 years, and subsequently examined. On the basis of the bacteriological results obtained from the adaptation series the test materials were classified into three categories, corresponding to the stimulation of bacterial growth: Group one, which allowed strong proliferation, included certain types of plasticized P.V.C. and Cellulose esters, as expected, and, as a new result, Polyurethane rubber; the latter showed clear signs of surface corrosion. Group two, which induced a clear but moderate growth, comprised a nylon trade type of Polyamide. Gruop three, allowing weak but still recognisable growth, included Formaldehyde pressure resing (Bakelite). This was surprising as it was thought that the formaldehyde and phenol components would exert a bacteriocidic or at least bacteriostatic effect. The results of the long and time consuming adaptation series with Pseudomonas aeruginosa were confirmed by the manometric dissimilation method of O. Warburg by means of the Braun/Melsungen apparatus. With this subtle but elegant procedure results and graphical recordings were obtained within hours and days...
Candida↗
Sensitivity to isopropyl alcohol.
Positive patch test reactions to isopropyl alcohol in connection with proved allergy to ethyl alcohol have already been published. A case of allergy to isopropyl alcohol with positive reactions to isopropanol (unpurified test material) and negative reactions to ethanol and methanol has also been reported. We report a case of a occupationally acquired sensitivity to isopropyl alcohol in which, on testing with gas chromatographically purified material, positive patch test reactions were found to 1-propanol, 1-butanol, 2-propanol, 2-butanol and methanal (formaldehyde) but not to the primary alcohols methanol, ethanol and amyl alcohol; not to the aldehydes acetal (acetaldehyde) and butanal; nor to the ketones acetone, butanon and isobutyl ketone, nor to methanoic (formic)acid. A tentative explanation for this peculiar pattern of reactions is given.
1-Propanol↗
Contact angles and wetting of pharmaceutical powders.
Contact angles of pharmaceutical powders were determined by the h-epsilon method, which consists essentially of measuring the maximum height of a drop of liquid fomed on a presaturated compact of the material. Determinations with aspirin as the test material indicate that the measured value is independent of the particle size of the powder and the porosity of the cake. The method was extended to include determinations on mixed powder systems. The results show that the hydrophobic material dominates with large particle-size powders; with small particle sizes, a linear relationship between the cosine of the contact angle of the mixed system and the proportion of the components is obtained. Results are presented for a wide variety of materials of pharmaceutical interest.
Aspirin↗
Assessment of tissue conditioning materials for functional impressions.
The validity of two types of tissue conditioning materials was studied and compared with that of two commonly used impression materials. The effect of three important factors on the accuracy of the impressions was observed. These factors were thickness of the impression material, time of compression of the impression, and the time interval before pouring the impression. A chrome-cobalt master cast was specially designed and 500 impressions were made and poured, resulting in 900 casts. Conclusions reached from this investigation were that: 1. Visco-Gel and Coe-Comfort tissue conditioning materials can be used as impression materials. 2. The dimensional accuracy of Visco-Gel is better than that of the Coe-Comfort impressions. 3. There is no significant difference between using a tray with a space of 1.5 mm or 3.0 mm for the impression material. 4. The less bulky the impression, the less time is required for compression with fewer inaccuracies. 5. It is preferable to pour the cast in the impression immediately or within 2 hours. 6. Both kinds of materials tested can be used as duplicating materials under certain conditions.
Dental Impression Materials↗
Performance of high frequency impaired listeners with conventional and extended high frequency amplification.
This study sought to determine if a high-pass hearing aid can provide increased improvement in word recognition and consonant discrimination over that of a conventional high frequency emphasis hearing aid in listeners with hearing loss limited to frequencies above 1 000 Hz. Word and consonant discrimination were assessed in quiet and in the presence of 12 talker speech babble for 10 subjects under three listening conditions: (1) unaided; (2) wearing a conventional high frequency emphasis hearing aid, and (3) wearing an experimental high-pass instrument. The speech testing materials included: (1) Northwestern University Auditory Test No. 6; (2) California Consonant Test, and (3) eight voiceless English consonants. Results suggested that both instruments provided similar benefit in quiet for improving word recognition and resolving consonant errors. For the noise condition, however, the experimental high-pass aid provided a considerable advantage in both word recognition and consonant identification and was particularly sensitive to reducing within- and between-manner voiceless consonant confusions. Furthermore, measurements of real-ear gain revealed that the high-pass aid afforded considerably greater acoustic gain above 4 000 Hz than that shown for the conventional high frequency emphasis hearing aid,20
Adult↗
Critical evaluation of prosthetic materials in repair of abdominal wall hernias: new criteria of tolerance and resistance.
Six different materials (3 mesh and 3 cloth) commonly used for the repair of abdominal wall hernias were evaluated in 180 rats after implantation through musculature and peritoneum. Serial macroscopic and bacteriologic investigations were done, and bursting strength of the wound was determined in all groups at intervals with an original device. Histologic criteria were used to characterize the resistance of the wound and the tolerance of the host to the foreign material. Statistical analysis of the results demonstrated: (1) after postoperative day 15, the resistance of the wound was similar for each material tested; (2) during this early period mesh materials exhibited more resistance to bursting pressures than cloth materials; (3) the incorporation of mesh material was constant, whereas encystment or extrusion was always observed after implantation of cloth material; (4) no infection occurred with mesh material, but significant bacteria were found in 18 per cent of cloth material implantations; (5) the extent of the cellular reaction, the enumeration of giant, inflammatory, and fibroblastic cells showed the superiority of mesh materials; and (6) the ratio of fibroblasts to inflammatory cells reflected closely the mechanical resistance and tolerance of the foreign material.
Abdominal Muscles↗
Material effects in shear-induced hemolysis.
A rotating-disk apparatus for shearing blood was employed to compare 22 materials for their tendency to cause hemolysis during standardized low-stress (130 dynes/cm2 maximum) laminar flow conditions. Rigid plastics, hydrogels, and carbons were among the materials tested. Time-independent ranking of the materials was possible for 75% of the data; these rankings correlated linearly (for polymers) with the critical surface tension gammac over the range 20--46 dyne/cm, with low gammac being associated with low hemolysis. Surface morphology was also found to influence hemolysis. Roughness in the 1--15 micron range had a distinct effect on hemolysis kinetics for polyethylene surfaces. This suggest that failure to find time-independence in 25% of the material rankings can be attributed to inadequate control of the roughness variable. It also emphasizes the importance of surface morphology, as well as surface chemistry, as a biocompatibility parameter.
Acrylamides↗
[Resistance and biological tolerance of six "inert" parietal protheses. Experimental and critical study (author's transl)].
Six different materials (3 mesh and 3 cloth) commonly used for the repair of abdominal wall hernias were evaluated in rats. 490 animals, distributed among four experimental groups, were implanted with one of the different prostheses through musculature and peritoneum. Serial macroscopic and bacteriological investigations were done. Using an original device, bursting strength of the wound was determined in all groups at intervals. Histological criteria were used to characterize the resistance of the wound and the tolerance of the host to foreign material. Statistical analysis of the results demonstrated that: 1) after the 15th post-operative day, the resistance of the wound was similar for each material tested; 2) during this early period mesh materials exhibited more resistance to bursting pressures than cloth materials; 3) the incorporation of mesh material was constant whereas encystment or extrusion was always observed after implantation of cloth material; 4) no infection occurred with mesh material but significant bacteria were found in 18 p. 100 of cloth material implantations; 5) the extent of the cellular reaction, the enumeration of giant, inflammatory cells and fibroblasts showed superiority of mesh material; 6) the ratio of fibroblasts/inflammatory cells reflected closely the mechanical resistance and tolerance of the foreign material.
Animals↗