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At least 1,369 records · Page 76Linked to original sources
PubMed1996

Accuracy of endodontic microleakage results: autoradiographic vs. volumetric measurements.

The correlation between autoradiographic and volumetric leakage measurements was evaluated. Seventy-two anterior teeth with a single canal were selected and divided into three groups of 24. Group 1 served as control (no obturation), group 2 was obturated with gutta-percha only, and group 3 was obturated with gutta-percha and endodontic sealer. Samples were placed in a vertical position in 48-well cell culture plates and immersed in 1 ml of [14C]urea for 14 days. One-mm-thick horizontal serial sections were cut with a diamond disk cooled with liquid-nitrogen gas. Linear penetration was recorded by five independent evaluators from autoradiographs. Volumetric results were based on counts per minute registered in a liquid scintillation spectrometer. Pearson's correlation coefficient test was used to determine the lineal correlation between both methods of evaluation. No acceptable correlation values were found in any of the three groups (group 1, r = 0.34; group 2, r = 0.23; group 3, r = 0.20). Our results indicate that there is no correlation between linear and volumetric measurements of leakage.

Analysis of Variance↗
PubMed1996

The sterilization of endodontic hand files.

Several different methods of file sterilization were analyzed to determine the best method of providing complete file sterility, including the metal shaft and plastic handle. Six test groups of 15 files were studied using Bacillus stearothermophilus as the test organism. Groups were "sterilized" by glutaraldehyde immersion, steam autoclaving, and various techniques of salt sterilization. Only proper steam autoclaving reliably produced completely sterile instruments. Salt sterilization and glutaraldehyde solutions may not be adequate sterilization methods for endodontic hand files and should not be relied on to provide completely sterile instruments.

Colony Count, Microbial↗
PubMed1996

Hardness and strength of endodontic files and reamers.

No information could be found in the dental literature on the hardness or strength of the materials in root canal instruments. Hardness testing is a convenient method for examining these products, and strength properties can be deduced from available strength-hardness data. The Vickers hardness of cross-sections of stainless steel root canal files and reamers #15 and #40 made by three well-known manufacturers were determined. Significant differences in hardness were found between manufacturers and between the two sizes of two manufacturers' products. The Vickers hardness range was from 400 to 651, exceeding the range permitted by the AS 1411, and falling below the hardness required for many cutting instruments. The measurements indicate that the instruments are made from high-strength wire. The values obtained suggest that the properties of materials used for some endodontic files could be improved and provide a basis for the selection of superior materials for the future.

Analysis of Variance↗
PubMed1997

Endodontic treatment in three cases of dens invaginatus.

Three cases of dens invaginated teeth with periapical lesions are presented in this article. In the first case the maxillary canine was treated with conventional endodontic treatment. The second and third cases, in mandibular and maxillary central incisors respectively, were treated surgically. Six months postoperatively all cases appeared radiographically to be improved.

Adolescent↗
PubMed1997

Disintegration of endodontic cements in water.

The disintegration of three endodontic cements in water was determined quantitatively and qualitatively. The materials studied were Ketac-Endo (KE), Tubli Seal (TS), and AH26 (AH). Specimens were immersed in water for 48 h (GI), 7 (GII) and 45 days (GIII). The solid residue was then determined. For the qualitative analysis three groups of tubes were filled with the materials and stored in water for the same periods. The exposed surface was photographed. Results expressed as percentage of original mass in the quantitative analysis for loss of mass due to dissolution were: GI = KE 2.39 (0.70); TS 3.56 (0.37); AH 4.94 (2.83); GII = KE 2.84 (0.30); TS 2.50 (0.50); AH 0.66 (0.26); GIII = KE 1.60 (0.84); TS 1.03 (0.42); AH 1.22 (0.54). Tukey's least significant difference (0.05) was 2.94. In the qualitative experiment KE disintegration was far more evident than that suffered by other materials. The quantitative results had no correlation with the qualitative observations probably due to the difference in the moment when the materials were immersed.

Bismuth↗
PubMed1998

Absorbency properties of different brands of standardized endodontic paper points.

A comparative study of the absorbency properties of different endodontic paper points has been conducted. Twenty standardized absorbent paper points, size 30, from 13 bands (Dentaline, Zipperer, Kerr, Diadent, Roeko novo, Roeko color, Maillefer, P.D., Schein, Spectrapoint, Proclinic, Euronda, and Alpro) of 12 manufacturers were tested. Each dry paper point was weighted using an electronic laboratory balance. A length of 16 mm from the tip was then lowered in distilled water for 5 s, the paper point was weighted again, and the difference between both measurements was taken as the value of the fluid absorbed. Diadent, Kerr, and Dentalite showed significantly higher absorbencies (p < 0.05) than standardized paper points of the remaining brands. The study demonstrates a wide variation in the absorbency properties of this dental accessory.

Absorption↗
PubMed1998

Effect of sterilization on cyclic fatigue of rotary nickel-titanium endodontic instruments.

The ability of heat treatment as a result of autoclave sterilization to extend the life of nickel-titanium rotary endodontic instruments by reducing the effect of cyclic fatigue was evaluated using 280 size 40 Lightspeed instruments. Instruments were cycled in artificial canals with angles of curvature of 30 degrees and either 2 or 5 mm radii of curvature. In a pilot study, instruments were sterilized or not sterilized and cycled to failure to obtain mean cycles-to-failure values for each group. In the first experimental protocol, instruments were cycled to either 25%, 50%, or 75% of the mean cycles-to-failure limit determined in the pilot study, then sterilized or not sterilized before being cycled to failure. In the second experimental protocol, instruments were cycled to 25% of the mean cycles-to-failure determined in the pilot study, and sterilized or not sterilized. The sequence of cycling to 25% of the predetermined cycles-to-failure limit followed by sterilization was repeated until the instruments failed. No significant increases in cycles to failure were observed between groups for either experimental protocol when instruments were evaluated at a similar radius. Significant differences in cycles to failure were only observed when instruments cycled to failure in the artificial canal with 2 mm radius were compared with instruments cycled to failure in the artificial canal of 5 mm radius. Scanning electron microscopic photos showed crack initiation and propagation in all instruments that were cycled to a percentage of the predetermined cycles-to-failure limit. It is concluded that heat treatment as a result of autoclave sterilization does not extend the useful life of nickel-titanium instruments.

Analysis of Variance↗
PubMed1998

Antibacterial effects of endodontic irrigants on black-pigmented gram-negative anaerobes and facultative bacteria.

The antibacterial effect of endodontic irrigants was evaluated against four black-pigmented Gram-negative anaerobes and four facultative anaerobic bacteria by means of the agar diffusion test. All solutions used were inhibitory against all bacterial strains tested. A 4% NaOCl solution provided the largest average zone of bacterial inhibition of this study that was significantly superior when compared with the other solutions, except 2.5% NaOCl (p < 0.05). Based on the averages of the diameters of the zones of bacterial growth inhibition, the antibacterial effects of the solutions could be ranked from strongest to weakest as follows: 4% NaOCl; 2.5% NaOCl; 2% chlorhexidine; 0.2% chlorhexidine, EDTA, and citric acid; and 0.5% NaOCl.

Analysis of Variance↗
PubMed1998

Microleakage of cavit in varnish-lined, matrix-supported endodontic access preparations.

The effect of the application of a matrix band and the use of cavity varnish on the microleakage of Cavit in endodontic access preparations was investigated. Sixty human upper premolars were divided into six groups of ten specimens each. Access cavities with proximal extensions were prepared and filled with 1, Cavit only; 2, Cavit after application of varnish; 3, Cavit with the use of a matrix band; 4, Cavit with a matrix band and varnish; 5, incremental deposition of Cavit with the use of a matrix band and varnish; and 6, gutta percha stopping. The specimens were placed in 2% methylene blue dye, thermocycled, and evaluated for both proximal and occlusal linear leakage. The experimental group in which Cavit was incrementally deposited in varnish-lined and matrix-supported cavities exhibited significantly (p < 0.05) less proximal microleakage than those groups in which cavities were filled without the application of both a matrix band and a cavity varnish.

Bicuspid↗
PubMed1998

Cytotoxic effect of endodontic bacteria on periapical fibroblasts.

This study was conducted to investigate the effects of sonicated bacterial extracts (SBEs) from anaerobic Gram-negative bacteria on periapical fibroblast obtained from the apical portion of human periodontal ligaments. Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum were chosen from among the endodontic bacteria isolated from root canals having a periapical lesion and compared in terms of their cytotoxicity. The purpose of this study was to examine which bacteria are involved in the development of periapical inflammation. The anaerobes were cultured under strict anaerobic conditions, and the bacterial cells were then harvested by centrifugation after incubation. The concentrated cell suspensions were sonicated and subsequently centrifuged. An SBE was made of each of the filtered supernatants. Each SBE was added to cultures of periapical fibroblasts. The cell growth and proliferation were measured by the MTT method after 3, 5, and 7 days. The SBEs from P. endodontalis, P. gingivalis, and F. nucleatum inhibited the growth of the fibroblasts, whereas the SBE from P. intermedia did not inhibit it. The SBEs from P. gingivalis and F. nucleatum inhibited the fibroblast growth more strongly than did the P. endodontalis, P. gingivalis, and F. nucleatum may participate in the development of periapical lesions.

Bacterial Proteins↗
PubMed1998

Mechanical properties of nickel-titanium endodontic instruments and the effect of sodium hypochlorite treatment.

The purpose of this study was to assess the mechanical properties--torsional moment, maximum angular deflection, maximum bending moment, and permanent angular deflection--of four brands of nickel-titanium (NiTi) endodontic file, and compare them with a conventional stainless-steel instrument, both in the presence and absence of sodium hypochlorite (NaOCl). NiTi instruments from four manufacturers were randomly selected and subjected to NaOCl treatment for 12 or 48 h, or not at all. The mechanical properties under test were then measured automatically by a digital torque memocouple. Torsional moment and maximum angular deflection indicate the resistance to torsional fracture of an instrument, maximum bending moment the stiffness of the instrument, and permanent angular deflection the strength of the base alloy. All instruments evaluated complied with or exceeded ADA/ANSI Specification No. 28, with the sole exception of the Maillefer ISO size 40 for torsional moment. JS Dental and McSpadden NiTi files were the most resistant to torsional fracture, but all NiTi files were inferior when compared with stainless-steel files from a previous study. However, NiTi files were superior in flexibility, and Maillefer and Brasseler instruments were the best of the instruments tested. NiTi files also had negligible permanent deformation angles. Furthermore, for all properties tested, NaOCl had no statistically significant effect.

Corrosion↗
PubMed1998

Rubber latex allergy and the endodontic patient.

Increasingly, patients with rubber latex allergy are being seen in dental offices. Health care workers, persons allergic to certain foods and those with certain medical histories are potentially latex-sensitive. This article presents the case of a patient with a history of severe rubber latex allergy and the associated management of an endodontically involved tooth. The possibility of the latex allergic patient being sensitive to gutta-percha obturation material is also raised.

Adult↗
PubMed1998

Relative efficiency of solvents used in endodontics.

A root canal model was used to test the relative efficiency of various commonly used endodontic solvents including eucalyptol, eucalyptus oil, orange oil, chloroform, and xylene to dissolve or soften gutta-percha and several different types of sealers (Proco-Sol, AH26, and Sealapex). There was no significant difference in the ability of the solvents to dissolve gutta-percha and the zinc oxide-eugenol-based sealer Proco-Sol. The resin-based sealer, AH26, was only dissolved in chloroform and took considerable time (> 30 min). The calcium hydroxide-based sealer, Sealapex, could not be tested because it was found not to set at all unless in contact with air. All of the solvents for both Proco-Sol and gutta-percha produced clinically acceptable dissolving times.

Analysis of Variance↗
PubMed1998

An evaluation of sterilization of endodontic instruments in artificial sponges.

The ability to sterilize endodontic files inserted into synthetic sponges was tested. Sponges were subjected to 5 cycles of either dry heat (Driclave) or steam under pressure (autoclave) sterilization. Sterilization was corroborated by microbiological tests. The sponges and files were pre-sterilized separately using steam under pressure. One hundred eighty files contaminated with Bacillus stearothermophilus spores (experimental and positive control) and 60 noncontaminated files (negative control), were inserted into 60 sponges. After each cycle, each file and a portion of sponge surrounding the file were transferred aseptically to tubes containing trypticase soy broth culture medium for bacteriological analysis. None of the tubes containing files and portions of sponges that were subjected to autoclave grew Bacillus stearothermophilus spores. Two of 60 (3.33%) of the tubes that were subjected to sterilization by Driclave demonstrated bacterial growth. Although the sponges tolerated the dry heat cycles well physically, sterilization was achieved in only 96.67% of the cases.

Animals↗
PubMed1998

An evaluation of Ektaspeed Plus film versus Ultraspeed film for endodontic working length determination.

Thirteen teeth in human cadaver sections were accessed and #15 K-files were placed at various lengths in one root canal of each tooth. Using a positioner to ensure duplicate views, radiographs were taken with both Ultraspeed and Ektaspeed Plus X-ray film. Each of the 26 radiographs was coded and then placed in random order. Six endodontic specialists measured the distance from the file tip to the radiographic apex on each film. The results were analyzed by analysis of variance and Cronbach's generalizability theory. It was found that 94% of the variance in measurements was due to differences among the viewers, whereas 5% was due to a combination of viewers and tooth. Only 1% was due to differences between the two types of film. It was concluded that Ektaspeed Plus film may be used for working length radiographs because it requires only approximately 50% of the radiation needed for Ultraspeed film.

Analysis of Variance↗
PubMed1999

An evaluation of the CO2 laser for endodontic disinfection.

The goal of this study was to evaluate the bactericidal action of the CO2 laser on animal teeth infected with an endodontic bacterial species. After instrumentation, 24 freshly extracted incisors were inoculated with a known concentration of Actinomyces odontolyticus and incubated anaerobically for 18 h. The incisors were separated into three groups: group 1--untreated control teeth; group 2--teeth treated with 3% NaOCl; and group 3--teeth lased with a CO2 laser at 5 W using three successive 9.9 s irradiation periods with 10 s between treatments. For each of the three groups, 60 microliters samples were removed using gel loading capillary pipette tips, and the diluted samples were plated in triplicate on Columbia agar plates. After a 5- to 6-day incubation, the colony-forming units were counted, and the quantitative results were subjected to an analysis of variance. The results of this analysis indicated an average 85% decrease in the colony-forming units in the laser-treated group, compared with the control group. According to Fisher and Scheffé tests, the differences in the averages between the control and laser groups were statistically significant (p < 0.05). The NaOCl treatment was statistically superior to the CO2 laser treatment.

Actinomyces↗
PubMed1999

Use of the microscope in endodontics: a report based on a questionnaire.

A survey regarding operating microscope (OM) usage and training was mailed to 3356 active members of the American Association of Endodontists (AAE) in the United States. Data from 2061 questionnaires indicate that 52% of the endodontists surveyed have access to and use the OM in their practice. The frequency of use as a function of years since completing endodontic training was as follows: < 5 yr, 71%; 6 to 10 yr, 51%; and > 10 yr, 44%. The OM was used most often for retrieval of separated instruments, root-end preparations, and root-end fillings. Of the respondents who use the OM, 36% report they do not use it as often as anticipated. The most common reasons reported were positional difficulties, inconvenience, and increased treatment time. The information collected from the survey reveals that the more training the operator has on the microscope, the more likely he or she is to use it for all procedures.

Chi-Square Distribution↗
PubMed1999

A comparative study of four coronal obturation materials in endodontic treatment.

The aim of this study was to compare, in vitro, the ability of temporary versus permanent materials to seal the access cavity. Eighty human maxillary single-canal teeth were prepared biomechanically and obturated with gutta-percha and an endodontic cement AH Plus, using the warm vertical compaction technique. All access cavities were sealed with 1 of 4 materials (Cavit, Fermit, Tetric, or Dyract). Microleakage was assessed by methylene blue dye penetration. The teeth were submitted to 100 thermocycles, with temperature varying from 0 degree to 55 degrees C. The greatest degree of leakage was observed with the temporary materials (Cavit and Fermit). There was a significant difference (p < 0.05) in leakage between all materials except between Dyract and Tetric. This suggests that it may be more prudent to use a permanent restorative material for provisional restorations to prevent inadequate canal sealing and the resulting risk of fluid penetration.

Calcium Sulfate↗