摘要:

Summary.. A total of 50 simulated root canals in clear resin blocks with various degrees and positions of curvature were prepared by either K‐files or Hedstrom files. Each file type was used to prepare 25 canals employing an in/out circumferential filing motion. The efficacy of the files was assessed by instrumentation time, deformation and fracture of instruments, and loss of working distance. The shape of the prepared canals was assessed by direct observation and from composite photographic prints produced by superimposing negatives of the canals obtained before and after preparation. Overall, canal shaping with Hedstrom files was quicker and more effective. Both file types prepared straight canals in an appropriate manner but the majority of prepared curved canals were hourglass in shape. In general, K‐files created zips which were wider and thus more pronounced than those produced by Hedstrom files. Wide ‘danger zones’ were also regularly created. The location of the aberrations depended largely on the original shape of the canal and in particular on the position of the beginning of the canal curve. Under the conditions of this study, the manipulation of K‐files and Hedstrom files in a simple in out circumferential filing motion proved an unsatisfactory method of shaping simulated curved root canals in res

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00514.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.A total of 50 simulated root canals in clear resin blocks with various degrees and positions of curvature were prepared by either K‐files or Hedstrom files. Each file type was used to prepare 25 canals employing an in/out circumferential filing motion. The efficacy of the files was assessed by instrumentation time, deformation and fracture of instruments, and loss of working distance. The shape of the prepared canals was assessed by direct observation and from composite photographic prints produced by superimposing negatives of the canals obtained before and after preparation. Overall, canal shaping with Hedstrom files was quicker and more effective. Both file types prepared straight canals in an appropriate manner but the majority of prepared curved canals were hourglass in shape. In general, K‐files created zips which were wider and thus more pronounced than those produced by Hedstrom files. Wide ‘danger zones’ were also regularly created. The location of the aberrations depended largely on the original shape of the canal and in particular on the position of the beginning of the canal curve. Under the conditions of this study, the manipulation of K‐files and Hedstrom files in a simple in out circumferential filing motion proved an unsatisfactory method of shaping simulated curved root canals in res

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00515.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.Electric pulp testers (EPTs) are widely used to assess tooth pulp vitality. With many unipolar EPTs the electrical circuit is completed through the operator. Since dentists now routinely wear rubber gloves, these might be expected to provide electrical insulation, and therefore to break the circuit. The objective of this investigation was to define the electrical effect of wearing rubber gloves.Two battery‐powered unipolar EPTs were examined using a digital storage oscilloscope with an input impedance of 1 MΩ. The probe tip was connected directly to the positive input lead of the oscilloscope. Three conditions were tested: (i) with the conductive handle connected directly to the negative input lead; (ii) with the ungloved operator holding the negative input lead in one hand and the conductive handle of the EPT in the other; and (iii) holding the conductive handle in a gloved hand.While the two EPTs produced different patterns of voltage spike, for each there was no difference between conditions (i) and (ii). However, when the conductive handle was held in a gloved hand (condition iii), there was a reduction in peak negative voltage and a change in wave form with positive overshoot. The alteration in wave form could be reproduced by substitution of the operator's gloved hand with a capacitance of 47 pF.These results support the hypothesis that a rubber glove acts partly as a capacitor in series with the electric pulp tester, and will alter the performance of EPTs unless the glove is bypassed electrical

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00516.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.The effect of post preparation on the apical seal of endodontically treated specimens was studied. The canals prepared in bovine bone were instrumented and obturated using five obturation techniques: the silver point technique, the lateral condensation of gutta‐percha technique, the warm vertical condensation of gutta‐percha technique, the Hygenic Ultrafil injection system and the Obtura technique.In addition to these five control groups, the five experimental groups were also subjected to post preparation. In the latter group, the gutta‐percha was removed with an engine‐driven root canal reamer 48 hours after obturation. Both the control and experimental groups were suspended in a 0.5 per cent crystal violet solution for 48 hours. After dye penetration, the specimens were immersed in liquid nitrogen and then split longitudinally.Linear measurements of the resultant apical dye leakage were determined by image processing. For each obturation technique, all specimens in both the control and experimental groups were recorded if they showed leakage.Using Fisher's exact probability test, it was shown that there was no significant difference between the obturation techniqu

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00517.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.This study was carried out to evaluate the incidence of postoperative pain in 68 patients requiring root canal therapy. The teeth studied contained non‐vital pulps and each had an existing open communication between the root canal and the oral cavity. Solvidont1irrigating solution and medication paste were used on a group of 36 patients, while a second group of 32 patients had sterile isotonic sodium chloride2(SISC) as the canal irrigant; no medicament was used on the second group. Three out of 36 patients (8 per cent) had mild discomfort following the use of Solvidont irrigant and paste. In the SISC group, 10 out of the 32 patients (31 per cent) complained of pain ranging from moderate discomfort to severe pain with associated swelling of soft tissues. Statistical analysis showed that the incidence of postoperative pain was high when the root canals of open teeth were not medicate

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00518.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Summary.An alternative to rubber dam is required to ensure nasopharyngeal protection during endodontic procedures on patients who are allergic to rubber compounds. The use of polythene sheeting as a practical alternative is described, illustrated and discussed.

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1989.tb00519.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.tb00520.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.tb00521.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY