摘要:

Summary.A total of 60 simulated root canals in clear resin blocks of various lengths and degree of curvature were prepared by hand with K‐files using a step‐back enlargement technique. The instruments were manipulated exclusively with a simple in/out filing or rasping motion with no attempt at roatation or twisting. The preparation technique was assessed by instrumentation, deformation and fracture of instruments, and loss of working distance. The shape of the preepared canals was assessed by direct inspection and from composite photographic prints produced by superimposing negatives of the canals obtained before and after preparation. In general, the preparations were time consuming and tedious to complete. Deformation and separation of instruments occurred mainly in those canals with short, severe curves. Loss of working distance was a universal finding and was associated to a degree with the straightening of curved canals inherent in their preparation. Prepared straight canals displayed a continuously tapering form being narrowest at their end‐points. On the other hand, prepared curved canals were invariably hourglass in shape. Under the conditions of this study the manipulation of K‐files in a simple in/out filing motion proved an unsatisfactory method of preparing simulated curved root canals in resin

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00908.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.It is assumed that above a critical level, microleakage causes periapical disease and jeopar‐dizes periapical tissue repair. The purpose of this investigation was first to find out to what degree obturation prevents leakage of bacteria‐sized particles or large protein molecules, and second it leakage of the commonly used dye methylene blue is comparable with that of a small bacterial metabolic product of similar molecular size.Sections, 9 mm long, obtained from 46 extracted human incisor roots had their root canals prepared in a standardized manner and obturated in four experimental ways using gutta‐percha. The root sections were mounted in the middle of tubes that were closed at both ends with rubber membrane stoppers, which permitted sampling from the apical reservoir. The coronal reservoir was filled with a solution of 1 mg/ml latex beads, 4 μg/ml endotoxin, 0.5 per cent butyric acid, 0.1 per cent valeric acid and 0.1 per cent methylene blue in water. After 1 and 2 weeks, samples were taken from the apical reservoir and tested tor the presence of latex beads by phase‐contrast microscopy, for endotoxin with a limulus lysate test, (or butyric acid with gas‐chromatography and for methylene blue with spec‐trophotometric analysis. Leakage of bacteria‐sized particles and large‐sized protein molecules could be prevented only when both sealer and pressure were used in obturating root canals with gutta‐percha. Leakage of butyric acid proved to be comparable with leakage of methylene blue; microleakage of these small molecules could not be prevented in this study whatever method o

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00909.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.When operated in air, the sonic endodontic instrument produced a movement at the driver head which resulted in a large elliptical oscillation of the file. This motion had similar properties to ultrasonically operated files in that there was a distinct variability in the magnitude of the vibratory motion between files of different design, length and thickness. When the sonic file was loaded, the elliptical motion was eliminated leaving a pure longitudinal file oscillation. This mode of vibration was particularly efficient as it was largely unaffected by loading, with the displacement amplitude being similar for different types of file used. The oscillatory pattern of the sonic file may offer a useful mode of mechanically assisted root canal preparaton.

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00910.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.Pulpotomy treatment was performed weekly on the teeth of four dogs for 5 weeks. Antibody formation to pulp tissue altered by parafor‐maldehyde paste within the pulp cavity was measured by enzyme linked immunosorbent assays (elisa). The results indicated that the reaction between antigen and antibody did occur when pre‐treatment or post‐treatment serum reacted with the antigen of either the pulp tissue incubated with saline or that incubated with paraformaldehyde paste. No evidence was found to prove that antibody formation was related to the pulpotomy treatment with paraformaldehyde

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00911.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.Two cases are presented in which api‐cally flared root canals have been successfully obturated with thermoplasticized gutta‐percha, following the failure of existing root filli

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00912.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.Ludwig's angina is an unusual sequel to endodontic treatment: such a case is described Principles of management are discussed with emphasis placed on the need to secure the airway early. The literature is reviewed.

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00913.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Book reviewed in this article:Principles and Practice of Operative Dentistry3rd edn, G. T. Charbeneau (ed.).Endodontology: Biologic Considerations in Endodontic Procedures2nd edn, S. Seltzer.

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00914.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.tb00915.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.tb00916.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.tb00917.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY