摘要:

Summary.Thisin vitrostudy evalutated the pattern of dentine removal when an ultrasonically energized file (Cavi‐Endo‐size 25 file) was applied to flat surfaces of dentine under standardized conditions. The influences of power setting, interfacial force between file and dentine, direction of file oscillation and operator‐assisted movement were examined. Impressions of the inswtrumented surfaces trevealed characteristic patterns consisting of a series of oblique creste, each one parallel to the next and separated by a constant distance along the line of contact with the file. Determination of height, width and separation of these crests with a Reflexd microscope aided objective asserssmennt.The simplest pattern was formed when the energized file was held against the dentine (power steeing = 1; interfacial force = 30g). Increasing the power setting to 8 caused deeper troughs over the apical 5 mm. The width of the crests corresponded to the taper of the file except at the apical tip where the crests were relatively wider. However, increasing the interfacial force to 60greduced the efficiency of the apical part of the file.The superimposition of operator‐induced movement greatly increased the extent of dentine removal, resulting in a tapering groove with a persistent crestal pattern. Oscillation of the file perpendicular to the dentine surface had a significantly greater influence on dentine removal, producing a deeper groove than was obtained with oscillation parallel to the surface.The findings may be of reevance in aiding controlled root canal preparation when using the Cavi‐Endo i

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00930.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.In an effort to simulate the infected dental root canal, bactria were enclosed in polyethylene tubes that were subcutaneously implanted into rats. Four different bacterial combinations, selected from nine oral species, were tested. The contents of 144 inoculated and implanted ‘root canals’ were analysed after 2 and 4 weeks of implantation.Bacteroides. Streptococcus, ActinomycesandFusobacteriumwere inoculated in low numbers but dominated the mixed flora at the end of the experiment. The bacteria‐filled tubes induced inflammation of the rat tissue at the implant opening (‘foramen’). It is confirmed that mixed bacterial populations survive, show succession and develop within an enclosed environment. Such florae cause significant inflammation at the interface with the hos

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00931.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.Evidence provided by the Brown and Hrenn stain for the presence of bacteria in fixed tissue sections depends on the ability to demonstrate them by staining. Previously, in a model experiment, it has been shown that demineralizing agents reduce the number of blue‐staining Gram‐positive bacteria (Wijnbergen&Van Mullem 1987). In the present study the influence of a structure‐destroying disinfectant, a structure‐preserving disinfectant or heat disinfection on number and stainability was investigated usingS. faecalissuspensions. Numbers were determined using a haemocytometer, and percentages of blue‐staining organisms were ascertained from smears. Immediately after disinfection the relative number of Gram‐positive staining bacteria was reduced by a factor of three for chlorhexidine, almost two for alcoformol, and was slightly reduced by heat. After 4 days of storage the reduction factors were 90, 4, and 2, respectively. After 14 days of storage the reduction factors were infinite, 30 and 5, respectively. These results were explained on the basis of the rate of cell wall destruction evoked by the respec

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00932.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.A prospective study was set up to evaluate a one‐visit apicectomy technique. Calcium hydroxide cement was used as the root canal filling material. The calcium hydroxide cement set rapidly and clearly revealed the position, size and outline form of the root canals at the level of resection. This facilitated preparation of the apical cavities to a depth of 3 mm. Each cavity was varnished before placement of the amalgam.Sixty‐eight patients (93 teeth) were included in the study. Five patients (8 teeth) were lost to follow‐up. The success rate, based on clinical and radiographic examination after a minimum of 2 years, was 91.8 per

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00933.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.A dye penetration technique was used to investigate the sealing ability of amalgam retrograde root fillingsin vitro. A factorial design was employed to determine the effect of amalgam fillings of 1, 2 and 4 mm in length with and without prior filling of the canals with gutta‐percha. The results were compared with a group of teeth filled with laterally condensed gutta‐percha alone and another with laterally condensed gutta‐percha plus root resection but with no retrograde filling. It was concluded that increasing the length of the amalgam filling did not improve the seal, that prior filling of the canal did not improve the seal, that retrograde root fillings were no worse than laterally condensed gutta‐percha alone and that root resection of teeth filled with laterally condensed gutta‐percha without retrograde filling was no worse than those filled with laterally condensed gutta‐percha without root resection or retrograde r

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00934.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.The sealing ability of retrograde root fillings of amalgam plus cavity varnish, EBA cement, glass ionomer cement, light‐cured composite resin, dentine bonding agent, and light‐cured composite resin plus dentine bonding agent were compared with laterally condensed conventional root fillings. A dye penetration technique was used to assess microleakage and it was concluded that none of the materials produced a perfect seal but that glass ionomer cement, light‐cured composite resin, light‐cured composite resin plus dentine bonding agent and dentine bonding agent alone produced better seals than conventional laterally condensed gutta‐percha, amalgam plus cavity varnish and E

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00935.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.Digital image analysis techniques enable the problem of examiner variability to be circumvented, and can be used to develop quantitative descriptions of bone lesions. This study investigated a method for describing periapical bone lesions.An edge‐detection technique was developed for application to routine periapical radiographs. Most periapical bone lesions appear radiographically as dark areas compared with the surrounding tissues. The digital imaging process resulted in an outline resembling the contour of the image of the lesion present. This contour could be successfully projected on to the original image with only limited operator assistance.Processing of the image resulted in increased definition of the structures present, with considerable noise reduction. The result was a simplified diagnostic examination process that promised a high degree of objectivity in periapical bone lesion detection.It is concluded that the results encourage further development of image processing techniques suitable for the definitive detection and diagnosis of periapical bone lesion

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00936.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00937.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00938.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00939.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY