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Hedström Files (hedström + file)
Selected AbstractsA survey of interfacial forces used during filing of root canalsDENTAL TRAUMATOLOGY, Issue 3 2000J. D. Regan Abstract , The pattern of dentine removal during endodontic instrumentation is influenced by many factors including the interfacial forces applied by the operator. The aim of this study was to investigate the influence of operators and different sizes and types of instruments on the magnitude of these interfacial forces. Single-rooted teeth were mounted on a cantilevered aluminium beam to which two pairs of single element strain gauges were joined in a half-bridge configuration and mounted at right angles to each other. The strain gauges were connected to an analogue-to-digital converter fitted in a micro-computer via conditioning amplifiers. This enabled strains to be recorded over a period of time. Twenty operators instrumented root canals using a series of hand instruments for 1 min each. The mean interfacial forces used by operators demonstrated a wide variation ranging from 9.06 g to 149.42 g (range of forces from 0,331 g) but there was a consistency in the relative magnitude for each operator. The 20 operators could be divided into 13 groups which were significantly different (,=0.05) from each other. There were significant differences (,=0.05) between the forces used for each of the K-Flex files (15, 25, 35, 45, and 70), the force increasing with the file size. There was also a significant difference (,=0.05) in the forces used between the Flexofile (#25) and the #25 K-Flex and Hedström files. However, there was no significant difference between the K-Flex and Hedström files. [source] Effectiveness of HERO 642 versus Hedström files for removing gutta-percha fillings in curved root canals: an ex vivo studyINTERNATIONAL ENDODONTIC JOURNAL, Issue 11 2009B. Ayd Abstract Aim, To compare the effectiveness of gutta-percha removal and the maintenance of canal anatomy when using the HERO 642 system or Hedström files (H-files) in mandibular molar teeth. Methodology, The root canals of 40 mandibular molar teeth were instrumented using H-files and filled with gutta-percha and sealer. After 1 year in storage, the roots were sectioned horizontally to provide apical, middle and coronal root thirds. Sections were photographed, and an individual muffle was produced for each tooth. Teeth were randomly divided into four groups (n = 10) and the gutta-percha removed using either the HERO 642 system or H-files, with or without solvent. Digital images of the root canals were then re-taken. Root thirds were inspected for lateral perforations, and the percentage of the residual canal filling was determined on postoperative images. Transportation and centring ratio were calculated using preoperative and postoperative images of the cross-sections of root thirds. Results, H-files groups were associated with less filling material than the HERO 642 system (H-files,HERO 642 P = 0.056, H-files,HERO 642+solvent P = 0.041, H-files + solvent,HERO 642 P = 0.018, H-files + solvent,HERO 642 + solvent P = 0.016). The percentage of residual filling material was similar in the apical thirds, and the contribution of solvent to canal debridement was not statistically significant (P > 0.05). Perforation occurred mesiobuccally in 48% of specimens in the apical sections of mesial roots. There were no significant differences for centring ratio, transportation and perforation rate between groups. Conclusions, H-files left less gutta-percha overall; however, there was no difference in the apical third. The effect of solvent was not remarkable. Both instrument systems created a large number of perforations. [source] Efficacy of ProTaper Universal rotary retreatment system for gutta-percha removal from root canalsINTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2008L.-S. Gu Abstract Aim, To evaluate the efficacy of the ProTaper Universal rotary retreatment system for gutta-percha (GP) removal from root canals. Methodology, Root canals of 60 extracted human maxillary anterior teeth were prepared and filled with laterally condensed GP and AH Plus sealer. Teeth were divided into three groups: group A , GP removal completed with the ProTaper Universal rotary retreatment system and with further canal repreparation accomplished with ProTaper Universal rotary instruments; group B , GP removal was completed using Gates Glidden drills and Hedström files with chloroform as a solvent, followed with further canal repreparation with ProTaper Universal rotary instruments; group C , the same as group B for GP removal with further canal preparation with stainless steel K-flex files (Kerr). The operating time was recorded. Teeth were rendered transparent for the evaluation of the area of remaining GP/sealer in bucco-lingual and mesial,distal directions. Statistical analysis was performed by using repeated measures analysis of variance and anova. Results, The ProTaper Universal technique (group A) resulted in a smaller percentage of canal area covered by residual GP/sealer than in groups B and C, with a significant difference between groups A and C (P < 0.05). Mean operating time for group A was 6.73 min, which was significantly shorter (P < 0.05) than group B (10.86 min) and group C (13.52 min). Conclusions, In this laboratory study all test techniques left GP/sealer remnants within the root canal. The ProTaper Universal rotary retreatment system proved to be an efficient method of removing GP and sealer from maxillary anterior teeth. [source] Efficacy of three rotary NiTi instruments in removing gutta-percha from root canalsINTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2008T. Ta, demir Abstract Aim, To investigate the ability of three rotary nickel,titanium instruments and hand instrumentation to remove gutta-percha and sealer. Methodology, Sixty freshly extracted human single-rooted teeth, each with one root canal, were instrumented with K-files and filled using cold lateral compaction of gutta-percha and AH Plus (Dentsply Detrey, Konstanz, Germany) sealer. The teeth were randomly divided into four groups of 15 specimens each. Removal of gutta-percha was performed with the following devices and techniques: ProTaper, R-Endo, Mtwo and Hedström files. The specimens were rendered transparent and the area of remaining filling material on the root canal wall was measured using a computer image analysis program. Statistical analysis was accomplished by Kruskal,Wallis and Mann,Whitney U -tests with Bonferroni correction for the analysis of residual root filling material and working time. Results, The ProTaper group had less filling material inside the root canals than the other groups, but a significant difference was found between only the ProTaper and Mtwo groups (P < 0.05). The retreatment time for Mtwo and ProTaper was significantly shorter compared with R-Endo and manual instrumentation with Hedström files (P < 0.001). R-Endo was significantly faster than manual instrumentation (P < 0.001). Conclusions, Under the experimental conditions, ProTaper left significantly less gutta-percha and sealer than Mtwo instruments. Complete removal of materials did not occur with any of the instrument systems investigated. [source] The effect of mineral trioxide aggregate on the apexification and periapical healing of teeth with incomplete root formationINTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2006W. T. Felippe Abstract Aim, To evaluate the influence of mineral trioxide aggregate (MTA) on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals and to verify the necessity of employing calcium hydroxide paste before using MTA. Methodology, Twenty premolars from two 6-month old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedström files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals of two premolars in each dog were left empty (control group). The other eight teeth in each animal were divided into two experimental groups. The apical thirds of the canals of group 1 were filled with MTA. In the teeth of group 2, the canals were dressed with a calcium hydroxide,propylene glycol paste. After 1 week, the paste was removed and the apical third was filled with MTA. All teeth were restored with reinforced zinc oxide cement (IRM) and amalgam. The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing. The sections were studied to evaluate seven parameters: formation of an apical calcified tissue barrier, level of barrier formation, inflammatory reaction, bone and root resorption, MTA extrusion, and microorganisms. Results of experimental groups were analysed by Wilcoxon's nonparametric tests and by the test of proportions. The critical value of statistical significance was 5%. Results, Significant differences (P < 0.05) were found in relation to the position of barrier formation and MTA extrusion. The barrier was formed in the interior of the canal in 69.2% of roots from MTA group only. In group 2, it was formed beyond the limits of the canal walls in 75% of the roots. MTA extrusion occurred mainly in roots from group 2. There was similarity between the groups for the other parameters. Conclusions, Mineral trioxide aggregate used after root canal preparation favoured the occurrence of the apexification and periapical healing. The initial use of calcium hydroxide paste was not necessary for apexification to occur, and has shown to be strongly related to the extrusion of MTA and formation of barriers beyond the limits of the root canal walls. [source] | ||||||||||