摘要:

AbstractA colloidal silica‐based substitute for the water added to dental porcelain has been developed which restricts rounding on firing and gives greater and indefinitely prolonged unfired biscuit strength. In conjunction with product evaluation, it has been found that both the modulus of rupture and the diametrical tensile strength of dental porcelains can be measured with a high degree of precisio

ISSN:0021-9304    

DOI:10.1002/jbm.820090103

出版商:John Wiley&Sons, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractSelf‐curing poweder‐liquid admixed acrylic systems are used for internal fixation of total hip and total knee prostheses. Gel permeation chromatography revealed that the polymer chain length distributions of set cements were basically unaffected by their curing pressures. However, a decrease of approximately 11% in porosity coupled with a measured increase in mechanical strengths could be induced through the use of high curing pressures well beyond those attainable by the surgeon in the current arthroplasties. The conclusion of the investigation was that, to improve such cements, attention should be focused on elimination of porosity rather than attempting to produce higher degrees of polymerizat

ISSN:0021-9304    

DOI:10.1002/jbm.820090104

出版商:John Wiley&Sons, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractThere is a continuing need for the complete characterization of the physica and chemical properties of dental materials. Among these properties is surface area. The problem is further complicated by the fact that most dental materials are, themselves, mixtures of two or more identifiable components. If the vapor adsorptive properties of these components are different in the mixture from that which would be expected of them collectively, then interaction is present. Interaction must not be confused with the lack of additivity which results from the limitations of the BET theory applied to mixtures. Equations are derived herein to estimate the extent of this latter source of variability and to correct for it giving a “true” surface area for the aggregate. Conversely, the adsorptive properties of either component can be calculated from the properties of the mixture and the remaining component together with the percentage composition. An immediate application can be made in determining the water‐vapor adsorptive properties of human dentinal collagen without necessitating its removal from dentin. Any attempt to extract it chemically may produce denaturation or chain rupture thus precluding the possibility of direct determination. In the case of nitrogen adsorption, however, interaction definitely is indi

ISSN:0021-9304    

DOI:10.1002/jbm.820090105

出版商:John Wiley&Sons, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractA number of carboxyl‐containing ethylene copolymers have been prepared which exhibit long term antibacterial and antifungal properties. These materials, containing antimicrobial agents bound to the copolymer backbone as carboxylate salts, have been tested for their applicability to hospital products as a means of providing “self‐sanitizing” articles. Tests have shown that these materials, although not bactericidal, do inhibit microbial growth. Investigations of the compatibility of these polymers with commodity polymers have been made and water emulsions of the polymers have been tested for applicability as components of product protectant c

ISSN:0021-9304    

DOI:10.1002/jbm.820090106

出版商:John Wiley&Sons, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractPowdered, sterilized zinc polycarboxylate was implanted subcutaneously in 56 young hamsters and 54 mice, using equal numbers of each sex, with 24 sham operated hamsters and 26 mice as controls. The hamsters were sacrificed after 15 months and the mice after 12. Implant material was recovered from one of 42 surviving mice and from 16 of 43 surviving hamsters. Benign adenomas of the gut, thyroid, sebaceous glands and ovary were found in 3 experimental mice and in one control. Benign adrenal adenomas were found in 3 experimental hamsters and in one control. One control hamster developed a rhabdomyosarcoma in a limb. One experimental hamster developed a leiomyosarcoma in close relation to an implant.

ISSN:0021-9304    

DOI:10.1002/jbm.820090107

出版商:John Wiley&Sons, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractThe study of collagen fibers by X‐ray diffraction, utilizing semiquantitative indices for appraisal of “structuration” and “orientation” was applied to 30 aortic valve grafts. These grafts, of pig origin, were studied in the fresh state, after tanning with aldehydes, and after having been implanted in patients for at least 18 months. It was shown that the collagen fibers are preferentially orientated parallel to the transverse axis of the valve cusps, and that this arrangement, enhanced by tanning, had a tendency to disappear in the post‐implantation samples. The structuration index which concerns the fibril network was also augmented by tanning, and was found a little high or slightly diminished in post‐implantation cusps. Evidence for a new compound, probably fibrin, was found in the diffraction patterns of implanted cusps, but crystallized calcium was noti

ISSN:0021-9304    

DOI:10.1002/jbm.820090108

出版商:John Wiley&Sons, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractA study has been carried out on the structure and surface texture of a new dental implant material composed of vitreous carbon balloons (3 wt % or 6 wt %) and poly(methyl methacrylate). Tooth replica implants using this material had been successfully placed in baboons, and histologic study revealed normal alveolar bone and a peri‐implant membrane with the connective tissue fibers oriented in a horizontal direction. Square wafers (10 mm × 10 mm × 1 mm) were studied, with the surface sandblasted in one‐half of the specimens. Light microscopy revealed that in the 3% carbon specimens, the vitreous carbon microballoons were evenly spaced and often appeared to be fragmented within their spaces. S.E.M. studies revealed a finely porous surface with numerous large craters. Microballons were often seen within the craters in the nonsandblasted spec

ISSN:0021-9304    

DOI:10.1002/jbm.820090109

出版商:John Wiley&Sons, Inc.    

年代:1975

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820090110

出版商:John Wiley&Sons, Inc.    

年代:1975

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820090111

出版商:John Wiley&Sons, Inc.    

年代:1975

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820090112

出版商:John Wiley&Sons, Inc.    

年代:1975

数据来源: WILEY