Biomedical subjects

O Zmener

Publications and source records attributed to O Zmener.

At least 19 recordsLinked to original sources

PubMed1995

Effectiveness of nickel-titanium files for preparing curved root canals.

In this study, the effect of 2 different endodontic files on the final shape of curved root canals of extracted single rooted teeth were examined in the scanning electron microscope. The instruments tested were a newly designed nickel-titanium endodontic file and a conventional K-type file. The files were used with in and out linear movements with a circumferential motion starting with a size 15 file. Final preparation of the apical thirds of the canals was performed with a size 35 file. Shaping effectiveness of the tested instruments was evaluated in terms of respect for conservation of the apical constriction and the presence or absence of ledging. Our observations revealed that more centered and tapered preparations were obtained with the use of the nickel-titanium files than with the conventional K-type files.

Dental Pulp Cavity↗

PubMed1995

Endodontic management of mandibular lateral incisor fused with supernumerary tooth.

In this article we report a case of a mandibular lateral incisor in which 3 separate root canals were located. Clinical and radiographic examinations suggested that fusion had occurred between the mandibular incisor and a supernumerary tooth. The endodontic management of the tooth is described, and repair of an apical periodontitis had occurred after 9 months.

Adolescent↗

PubMed1995

Cleaning of endodontic instruments before use.

In this study, 120 new K-files and Hedström files from 3 different manufacturers were examined for surface debris with the scanning electron microscope. The instruments were examined immediately upon removal from their original packages. A second examination of the instruments was performed after they were cleansed in an ultrasonic bath. None of the studied instruments were free of metallic spurs or foreign particles as received from the manufacturers. The ultrasonic bath used together with a cleanser solution appeared to be an effective method to minimize the surface impurities from the manufacturing process prior to use in patients.

Decontamination↗

PubMed1994

Effectiveness of two different methods for preparing curved root canals.

In this study, the effect of using two different methods for preparing curved root canals of extracted, single-rooted teeth were analyzed with the scanning electron microscope. The instrumentation systems tested were the Canal Master and a standard circumferential filing technique in which conventional K-files were used. Shaping effectiveness was qualitatively evaluated in terms of respect for conservation of the apical constriction and the presence or absence of ledging, specially in the apical third of the root canals. As a result of our observations, it appeared that the Canal Master instrumentation technique provided well-centered and tapered preparations. Conversely, the use of conventional K-files with a standard circumferential filing technique resulted in frequent alterations of the initial pattern of the root canals, showing transportation of the apical foramen and ledge formation.

Dental Pulp Cavity↗

PubMed1992

Effectiveness of different endodontic files for preparing curved root canals: a scanning electron microscopic study.

In this study, the effect of using four endodontic files from different manufacturers on the final shape of 80 prepared curved root canals of extracted single-rooted teeth were comparatively analyzed with scanning electron microscopy. The instruments tested were Tri-files, Flex-R files, Flexofiles and conventional K-type files. All files were used with in and out linear movements with a circumferential motion starting with a size 15 file. Final preparation of the apical thirds was performed with a size 30 file. Shaping effectiveness of the tested files was qualitatively evaluated in terms of respect for conservation of the apical constriction and the presence or absence of ledging, specially in the apical third of the root canals. A well-centered and tapered preparation without apical transportation or ledging was detected when Tri-file or Flex-R files were used. Conversely, the use of Flexofile or conventional K-type files resulted in frequent alteration of the initial pattern of the root canals, showing an hour-glass preparation with alteration of the apical constriction and ledge formations.

Dental Cavity Preparation↗

PubMed1991

SEM study of surface architecture of gutta-percha cones.

The apical third of 60 standardized, gutta-percha cones obtained from six different manufacturers were analyzed by scanning electron microscopy. Despite the fact that the majority of the commercial gutta-percha cones showed rather uniform and smooth surfaces, some displayed morphologic variations such as gross protuberances or deeply cratered areas containing numerous free or entrapped crystal-like particles.

Gutta-Percha↗

PubMed1991

Surface architecture of a low-temperature thermoplasticized gutta-percha.

The surface characteristics of two Ultrafil materials, Regular set (RS) and Firm set (FS) were analyzed by scanning electron microscopy (SEM). The samples of Ultrafil were obtained from both RS and FS cannules which were pre-heated to 70 degrees C. Another RS and FS samples were obtained at room temperature from un-heated cannules. Samples of standard gutta-percha points obtained from the same manufacturer were studied for comparative purposes. RS samples obtained from pre-heated and un-heated cannules exhibited rough surfaces containing randomly distributed crystal-like structures. Heated and un-heated FS samples featured smoother surfaces with fewer crystal-like structures. The gutta-percha points also exhibited smooth surfaces and absence of crystal-like structures. The consequence of the possible release of these structures from Ultrafil in a biological system is discussed.

Gutta-Percha↗

PubMed1991

Thermomechanical compaction of gutta-percha: a scanning electron microscope study.

The root canals of 20 freshly extracted maxillary central incisors and canines were prepared and filled by thermo-mechanical or lateral condensation of gutta-percha cones without sealer. The adaptation of the filling material to the root canal walls was then examined with a scanning electron microscope. A more homogenized mass of gutta-percha could be detected in teeth filled by thermomechanical compaction of gutta-percha cones. The morphology of the prepared root canal system was well reproduced by the use of both techniques.

Dental Pulp Cavity↗

PubMed1991

A case of progressive external root resorption.

This case report describes a radiographical, histological and histochemical study of an extracted mandibular tooth with progressive external root resorption. The cells which appeared to be responsible for the hard tissue resorption showed an intense acid phosphatase activity, similar to that of bone-resorbing cells. Some aspects on the etiology and pathogenesis of resorptive process that occurred in the present case are discussed.

Acid Phosphatase↗

PubMed1990

Tissue response to an experimental calcium hydroxide-based endodontic sealer: a quantitative study in subcutaneous connective tissue of the rat.

Silicone tubes containing a freshly mixed experimental Sealapex, in which titanium dioxide was removed from the original formula, were implanted in the dorsal subcutaneous connective tissue of the rat. Solid silicone rods of the same size as the tubes were also implanted and used as inert controls. The tissue reaction to both these materials was histometrically and quantitatively studied under light microscopy and by elemental electron microprobe analysis. After 7, 30 and 90 d of implantation, different grades of tissue reaction to the tested materials were recorded. A granulomatous tissue containing numerous foreign-body giant cells and macrophages with engulfed particles in their cytoplasms was initially detected in contact with the test material. In addition, many fibroblasts and newly formed vessels were also observed at these areas. The results of this study revealed that these reactions increased progressively at the 30- and 90-d observations. The electron microprobe analysis of the granulomatous tissues showed the presence of heavy components of the experimental material.

Animals↗

PubMed1989

Unusual case of silver cone disintegration.

An unusual case of silver cone disintegration associated with progressive root resorption is reported. The use of the scanning electron microscope and the electron microprobe provided evidence of different states of corrosion in two remaining silver cones. Light microscopic examination showed the presence of silver particles apparently released from the disintegrated or progressively corroded cones in the surrounding tissues. The possible interaction between such silver accumulations or their chemical combinations with other elements and the tissue is discussed.

Corrosion↗

PubMed1989

A radiographic, histological, and histometric study of endodontic materials.

Silicone tubes filled with CRCS, a calcium hydroxide-based cement, were implanted at two different localizations in the right tibias of white male Wistar rats. A similar number of solid silicone rods were implanted in the left tibias of the same animals and were used as inert controls. Fifteen days after implantation the bone tissue reactions to these materials were evaluated by means of radiographic, histological, and histometric methods. The radiographic and histometric analysis of the tissues around the deep end of the implants showed that the amount of reactional bone formation in contact with CRCS was significantly lower than that observed in contact with the controls (p less than 0.01). Also, the cell counts obtained from the tissues in contact with CRCS were significantly less than those obtained from the controls (p less than 0.01). This methodology appears to be a refined procedure for analyzing the possible toxic effects of endodontic materials in bone tissues. However, we feel that more extensive experiments will be necessary before predicting the long-term results which could be obtained from this experimental model.

Animals↗

PubMed1989

Effects of two gutta-percha formulations and one zinc oxide-eugenol and Canada balsam mixture on human blood monocytes and lymphocytes.

In this study we performed an in vitro assay of the effects of two gutta-percha formulations and one zinc oxide-eugenol and Canada balsam-based endodontic material on the behavior of a mixed cell population of human monocytes and lymphocytes. Cells were cultured either in direct contact with or near experimental samples of Ultrafil, standard gutta-percha cones or Endoseal and the inhibitory effects of these materials upon cell attachment and spreading on test surfaces were analyzed. Ultrafil and the standard gutta-percha cones showed little or no adverse effects, whereas the inhibitory effects of Endoseal appeared to be severe. There were statistically significant differences between the results obtained from both Ultrafil and gutta-percha cones and those obtained from Endoseal. Differences between all tested materials and their respective controls were also statistically significant.

Balsams↗

PubMed1988

Silver accumulations in periapical granulomas: report of five cases using the scanning electron microscope, the electron microprobe, and other complementary methods.

A series of cytologic imprints obtained from periapical granulomas were studied with the conventional light microscope, the scanning electron microscope, and the electron microprobe to analyze the chemical composition of several black deposits that were randomly observed near or in the cytoplasm of macrophages and multinucleated giant cells. These granulomas had been removed from endodontically treated human teeth in which the root canals had been obturated with silver cones and Grossman's sealer 3 to 5 years previously. To investigate whether corrosion had occurred on the silver cones, the cones were also examined with the scanning electron microscope and the electron microprobe. Our observations revealed that all the examined silver cones showed different degrees of corrosion on their surfaces, whereas different concentrations of silver, sulfur, and chlorine were detected at the same sites in the cytologic imprints. However, it is impossible to determine from this study whether the presence of corrosive by-products in the periapical tissues is responsible for the development of a pathologic reaction at these sites.

Adolescent↗

PubMed1988