摘要:

SummaryThe objective of this laboratory study was to compare root‐end cavities prepared with sonic Retro‐prep tips in a MM 1500 Sonic Air handpiece with those created by burs in a conventional handpiece. A total of 80 single‐rooted extracted human teeth with mature apices and straight canals were included in the study. Four groups of 20 extracted teeth were prepared as follows: I, a 3‐4 mm root‐end resection perpendicular to the long axis of the root, with a size 40 sonic Retro‐prep tip creating an apical cavity 3 mm into root canal system; II, a 45° bevel of the root‐face removing a 3‐4 mm root segment and root‐end preparation as per group I; III, root‐end resection as per group I, with an apical cavity prepared using a size 010 inverted cone bur 3 mm down the long axis of the root; IV, resection as per group II, followed by an apical cavity preparation with a size 010 inverted cone bur 3 mm into the root canal system. The apical root portion and root‐end cavities were replicated and prepared for SEM analysis at × 20 and × 80 magnification. The degree of chipping associated with the margin of the root‐end cavities, as evaluated with a standard grading system, and the incidence of root‐face cracks were noted. Marginal chipping of root‐end cavities prepared using sonic instrumentation was significantly worse than that produced by burs (P<0.001). Perpendicular root‐end resections showed significantly better scores than bevelled root‐end resections (P<0.005). The incidence of root‐face cracking was low with no significant differ

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01388.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryThe cutting efficiency for sizes 25 and 35 stainless steel Hedstrom S and U files from 10 manufacturers, and titanium‐alloy Hedstrom S and U files from five manufacturers, tested for linear (filing) motion under standardized conditions were determined. Special plastic samples having well‐defined abrasive properties were used as the substrate and constant pressure was applied until the instruments were blunt. The depth of the groove achieved by filing was used to measure cutting efficiency. For both sizes there were significant differences in the cutting efficiency of files made by the various manufacturers (P<0.001). Hedstrom files made of stainless steel, made by VDW, gave the best cutting efficiency for sizes 25 and 35. Overall, under the conditions of this study, Hedstrom files had better cutting efficiency than S or U files. Likewise, stainless steel files provided better cutting efficiency than instruments made of titanium all

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01389.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryThe aims of this study were to develop a model system capable of monitoring lateral forces during root canal preparation and to measure the cutting ability of files activated by the MM 1500 sonic handpiece. Forces were monitored by a calibrated model system which utilized a combination of spring steel beams fitted with strain gauges, these were interfaced through two strain gauge amplifiers to an x‐y recorder. Single rooted canine teeth (n= 36; 32 experimental, four control) were mounted in a two‐part acrylic mould (which was an integral part of the model system) prior to sectioning horizontally 11 mm from the tooth apex. A 24full factorial experiment with two replications was performed. Four variables were selected for evaluation, load (50 and 100 g), power (air inlet ring half or fully open), file type (Heliosonic or Shaper) and stroke rate (1 or 2 cycles per second). A new file (size 25) was used for 1 min in each canal with water irrigation. The control group was not instrumented. The cross‐sectional root canal area was measured before and after instrumentation using image analysis and increase in area was used as an indication of cutting ability. The results showed that the increase in load, power and the Shaper file all produced a significant increase in cutting ability (ANOVA,P0.05). In conclusion, this work has developed a model system to monitor lateral forces and has shown that instrument design and operator usage affect dentine removal from a root canal

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01390.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryForty‐five acrylic blocks with simulated curved canals were divided into three groups of 15 blocks each. In group 1 the canals were instrumented with ultrasoni‐cally energized K‐files (UEF) using a piezoelectric ultrasonic device. In group 2 the canals were prepared with ProFile 0.04 Taper Series 29 Rotary Instruments (PRI) in conjunction with a low‐speed high torque handpiece. In group 3 (control) the canals were hand instrumented (HI) with conventional K‐type files using a standard push‐pull circumferential technique. The efficiency of these techniques for preparing the simulated canals were compared by measuring the amount of transportation of the prepared canals at different levels from the working length using a double exposure photographic technique. A statistical analysis was used to indicate any significant difference among groups. The results showed that the use of PRI provided well‐centred and more tapered preparations. Conversely, the use of UEF and HI resulted in frequent alteration of the original curvature, showing transportation at different levels from the w

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01391.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryActinomyces israeliihas been repeatedly implicated as a cause of failure of endodontic therapy. This study investigated the antimicrobial effect of antibiotics as well as intracanal medicaments, sodium hypochlorite solution and calcium hydroxide, on this important pathogen. Growth ofA. israeliiwas inhibited by low concentrations of antibiotics, yet high concentrations were not bactericidal forA. israeliiover 1 week. WhenA. israeliiwas exposed for 2‐6 weeks at concentrations equivalent to clinical serum levels, the antibiotics were lethal. The results reveal a species ‐ specific antibiotic tolerance forA. israelii.Both sodium hypochlorite solution and calcium hydroxide were found to be highly eifective in killingA. israe

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01392.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryAnin vitroinvestigation was performed to assess the extent of apical dye leakage in relation to root fillings made by Thermafil obturators and the lateral condensation of gutta‐percha in extracted human teeth under conditions of passive dye penetration, centrifugation, a vacuum technique and an increased air pressure technique. One hundred and twenty‐eight extracted teeth were selected and prepared. The specimens were allocated into eight closely matched experimental groups. Four groups were obturated with Thermafil obturators and four with the lateral condensation technique. Microleakage was assessed after exposing one group of specimens from each of the obturation techniques to each of the four dye penetration systems using India ink as the leakage detector. The teeth were demineralized and cleared prior to examination and the maximum dye penetration for each specimen was recorded. The statistical analysis on transformed data revealed no significant differences between the four microleakage techniques and no differences between the two obturation techniq

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01393.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryRubber dam clamps are known to break during clinical use in endodontics. Thisin‐vitrostudy examined some of the variables which may contribute to the fracture. Stainless steel rubber dam clamps were subjected to various cleaning and autoclaving regimes and exposure to various solutions of sodium hypochlorite (NaOCl). Each clamp was examined after four cycles of cleaning and exposure to NaOCl. During environmental exposure to NaOCl, the clamp was stressed over a perspex rod to simulate placement onto the crown of a tooth. Clamps were examined after each test cycle visually and microscopically, or immediately after breakage. Results suggested that the fractures were because of a stress corrosion cracking phenomenon. There was evidence of intergranular and transgranular cracking of the metal. Corrosion spots were seen on the surface of the clamps and fracture occurred mainly through these spots. A number of recommendations to reduce breakage of clamps have been suggeste

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01394.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01395.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Book reviewed in this articles.Clinical Periodontology, 8th edn. Edited by F. A. Carranza, Jr.&M. G. NewmanIllustrated Anatomy of the Head and Neck M. J. Fehrenbach&S. W. HerringOral Medicine — A Pocket Guide. L. R. Everso

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01396.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01397.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY