Biomedical subjects

Arpád Fazekas

Publications and source records attributed to Arpád Fazekas.

6 recordsLinked to original sources

PubMed2006

[Problems with working length determination during endodontic therapy].

Accurate working length (WL) determination is a crucial part of successful root canal therapy. Working length is the distance from the coronal reference plane to the apical constriction. The apical constriction, also referred to as cementodentinal junction, represents the transition between the pulpal and the periodontal tissues. It is widely accepted that canal preparation and filling should be terminated at that point. However, the location and form of the apical constriction are variable and not always detectable. Moreover, the available clinical methods used for WL measurements are also inaccurate. At present two methods are recommended in dental practice for determination of WL: radiographic technique, and by the means of electronic apex locators. Advantages and disadvantages of the two methods are discussed in this paper.

Electronics, Medical↗

PubMed2003

In vitro kinetic study of absorbency of retraction cords.

STATEMENT OF PROBLEM: The soaking time required for liquid uptake by retraction cords is a crucial factor in the successful gingival retraction procedure. PURPOSE: The aim of this investigation was to determine the optimal soaking time for 3 retraction cords of different thickness to ensure adequate uptake of the hemostatic solution. MATERIAL AND METHODS: Braided ULTRAPAC retraction cords of 3 different thicknesses (No. 00, No. 0, and No. 1) with identical lengths (35 mm) were used. The capability of the cords to absorb liquids was measured by a gravimetric method. Different sulcus retraction solutions (epinephrine, aluminum chloride, and ferric sulfate) were tested, with physiological saline solution used as the control. The cords were soaked for various time intervals (2 seconds; 1, 5, and 60 minutes; and 24 hours) in the medicament solutions at room temperature. Immediately before immersion, air inclusions that may have inhibited the inner moistening of the cords were manually pressed out. In each of the 4 treatment groups, 75 pieces of cord were tested by determining the grams of fluid absorbed by grams of dry cord (gram/gram). Before the cord was weighed, excess fluid accumulating on the outer surface of the cord was removed by filter paper saturated in the corresponding test solution. The data were analyzed by F test analysis, and P<.05 was regarded as significant. RESULTS: In each group, regardless of the cord type (No. 00, No. 0, or No. 1) or medicament solutions tested, the amount of fluid absorbed increased with the soaking time, but to different extents. A logarithmic relationship in a linear plot between the amount of fluid absorbed and the soaking time was demonstrated. The relationship established offered an exact determination of both the rate and the saturation level of liquid uptake. The rate of liquid uptake calculated from the saturation equations exhibited significant correlation with the cord thickness (P<.05). The saturation levels of the solutions did not show correlation with the cord thickness (P>.30). CONCLUSION: Within the limitations of this study, the results indicated that 20 minutes of soaking time was necessary for saturation of the cords before use, provided that air trapped within the cords was removed. In addition to the soaking time, the saturation of the cords with the solutions largely depended on the wetting of the cords.

Absorption↗

PubMed2002

Antimicrobial efficacy of various root canal preparation techniques: an in vitro comparative study.

In this study, we compared the antimicrobial efficacy of various root canal preparation techniques and instruments in the root canals of 40 human first maxillary premolars extracted for orthodontic reasons. After extirpation of the pulp, teeth were sterilized in an autoclave. Then, the root canals were infected with Enterococcus faecalis suspension and the teeth incubated at 37 degrees C for 24 h. Thereafter, the teeth were divided into five groups: preparation with K-file or K-Nitiflex file (step-back technique; groups 1 and 2), K-reamer (standardization technique; group 3), irrigation only (group 4), and no treatment (group 5). Before and after treatments, samples were taken for culture. Results were evaluated after 24-h incubation in E67 selective culture medium. We observed a considerable reduction in bacterial population after mechanical preparation. No significant differences were seen among the efficacy of the various preparation techniques and files used.

Bicuspid↗

PubMed2002

[Advancements in dental preparation technique (literature review)].

This paper has reviewed the literature on the methods of cavity preparation. The different methods are summarised in Table 1. Nowadays rotary instruments are accepted as standard for cavity preparation. The limitation of using a rotary instrument is the iatrogenic damage to adjacent teeth. Therefore some of the hand instruments remained an essential part of quality restorative dentistry. In order to reduce iatrogenic injury oscillating instruments had been developed. The oscillating instruments change the rotary movement into an oscillating movement and copy the shape of the working tip through an abrasive medium to the tooth surface. The abrasive medium is generally diamond. A new possibility in tooth preparation is the Er:YAG laser. It can be used for both cavity preparation and caries removal. The chemo-mechanical caries removal means the selective chemical softening is followed by the mechanical removing of carious dentin.

Dental Caries↗

PubMed2002

[Kinetic study of the liquid uptake of retraction cords].

The soaking time ensured for the liquid uptake of retraction cords is a crucial factor in the successful gingival retraction procedure. The aim of the present investigations was to determine the optimal soaking time for three cords of different thickness. The capability of liquid uptake of the cords was measured by a gravimetric method using four different sulcus retraction solutions. In addition to the time of soaking, the saturation of the cords with the solutions largely depended on the wetting properties and the pore structure of the cords as well. Our results indicate that 20 minutes soaking time is necessary for saturation before using in the clinical application of the cords. This conclusion applies for conditions when air bubbles are manually removed before soaking.

Dental Instruments↗

PubMedDate not supplied

Effects of pre-soaked retraction cords on the microcirculation of the human gingival margin.

In the direct treatment of cervical lesions and to improve the impression-making procedure prior to fabricating indirect restorations, exposure of the gingival sulcus and control of hemorrhage or gingival fluid seepage are a prerequisite. For gingival displacement, cords impregnated with medicaments are widely used. In this investigation, the authors first studied in vitro the time course of fluid absorption by retraction cords immersed in test solutions. Thereafter, in a clinical trial, they examined the microcirculatory responses of the gingival margin after subgingival insertion and removal of retraction cords pre-soaked in solutions containing saline, AlCl3, Fe2(SO4)3 or epinephrine. Blood flow was recorded using laser Doppler technique. Blood perfusion fell markedly upon inserting the retraction cord, and this response was invariably present with all the compounds tested. After five-minutes, the decrease became less apparent with cords that were impregnated with physiological saline, AlCl3 or Fe2(SO4)3. Removing the cord elicited a prompt, marked and sustained increase in gingival microcirculation. However, removal of the cord impregnated with 0.1% epinephrine failed to reverse the decreased perfusion, and blood flow to the gingival margin remained low over an additional 20-minute observation. The results of this study indicate that with the exception of epinephrine, all retraction substances tested produced gingival hyperemia for operative procedures. Only epinephrine exhibited sustained vasoconstrictor response. It is anticipated that using laser Doppler flowmetry may be a suitable technique to evaluate the appropriate concentration of epinephrine that would elicit topical vasoconstriction.

Absorption↗