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Biomedical subjects

M Staninec

Publications and source records attributed to M Staninec.

At least 37 records · Page 2Linked to original sources
PubMed1992

Effect of bonded gold inlays on fracture resistance of teeth.

The purpose of this study was to determine if bonding gold inlays to tooth structure with an adhesive resin cement would increase the fracture resistance of restored teeth. Extracted paired maxillary premolars were prepared for mesio-occlusodistal inlays, and the inlays were cast in type II gold. In one tooth of each pair, the inlay was sandblasted with aluminium oxide, tin plated, and cemented with an adhesive resin into the etched preparation. For the other (control) tooth in each pair, the inlay was sandblasted and then cemented into the preparation with zinc phosphate cement. The teeth were thermocycled and loaded until fracture. The teeth in the bonded group had a statistically significantly higher fracture resistance than did the teeth in the control group. Scanning electron microscopic examination revealed that failure in the bonded group occurred predominantly within the resin.

Bicuspid↗
PubMed1989

Comparative evaluation of the sensitometric properties of screen-film systems and conventional dental receptors for intraoral radiography.

This investigation determined the sensitometric properties of 27 rare-earth screen-film combinations and compared them to E- and D-speed films and xeroradiography, the current standards for intraoral radiography. A series of exposures from base plus fog to film saturation were made to determine the Hurter and Driffield curve of each image receptor. The base plus fog, film saturation, speed, gamma, average gradient, and resolution were determined. When dental receptors and screen-film systems are compared on the basis of radiographic quality (contrast and resolution), many screen-film systems have similar resolution (greater than 10 line pairs/mm), significantly greater contrast (greater than 2.0), and a substantial speed advantage (greater than 10). Thus selected screen-film systems may be an alternative to conventional dental receptors for intraoral radiography.

Evaluation Studies as Topic↗
PubMed1989

Effect of developer temperature changes on the sensitometric properties of direct exposure and screen-film imaging systems.

A heat exchanger was developed and incorporated into the recirculation system of a dental processor to maintain strict temperature control. Without the heat exchanger, developer temperature rose steadily over 8 h to a maximum of 35.7 degrees C: with the heat exchanger it was maintained, regardless of ambient conditions, at the desired temperature with virtually no fluctuation. Sensitometric properties of base and fog, speed, and average gradient were measured for D and E speed films and Lanex Regular/T-Mat G and Lanex Fast/T-Mat Hscreen-film systems at developer temperatures of 21.1, 23.8, 26.7, 29.4 and 32.2 degrees C. Small changes in these properties were found for D and E speed films: on the other hand, Lanex Regular/T-Mat G showed a 65% increase in base and fog and Lanex Fast/T-Mat H a 43% increase in average gradient over the temperature range studied. Although these changes may not be clinically significant for intra-oral and dental radiography, the variations in image quality may compromise controlled imaging experiments and clinically compromise radiographic quality when using screen-film systems.

Radiography, Dental↗
PubMed1989

Rare earth filters for intraoral radiography: exposure reduction as a function of kV(p) with comparisons of image quality.

Radiographs of phantoms were produced using E-speed film and various rare earth X-ray beam filters. The rare earth filters considerably reduced the amount of radiation needed to produce diagnostic quality images and, in many cases, improved image quality. These filters can be implemented easily and inexpensively in a clinical setting, resulting in radiation exposure reductions of up to 71%.

Filtration↗
PubMed1989

Comparison of backscattered scanning electron microscopy and microradiography of secondary caries.

Carious lesions are usually studied using light microscopy and/or microradiography which require preparation of thin sections. Backscattered scanning electron microscopy (BSEM) has received little attention although it provides information similar to that obtained with microradiographs, with the potential for higher resolution. Recently, microscopes have been introduced that can be used to study wet or nonconducting specimens, offering techniques for studying specimens without desiccation or preparation of thin sections. This investigation sought to determine if secondary carious lesions have the same characteristics when studied by microradiography as when using the "wet" BSEM mode. Microradiographs were made of thin sections from restored teeth with secondary caries induced in an artificial caries system. The thin sections were also studied by BSEM with a partial pressure in the specimen chamber to prevent specimen charging. Comparisons of the lesion size and shape were made using the two methods. Lesion depth measurements in enamel were the same; lesions that penetrated into dentin appeared to be of similar size and shape, but lesion depths measured by BSEM were slightly greater (paired t-test, p less than .05). This was a result of cracks at the carious enamel-dentin interface that probably developed during storage of the samples. Variations in the surface enamel rod structure and the development of subsurface lesions were apparent. Several zones were also apparent in the carious dentin, demonstrating loss of dentinal tubule detail in the depth of the lesion, collapse of tubules, and hypermineralized regions near the advancing front of the lesion. Several additional samples of natural carious teeth were examined. They demonstrated the characteristic structural features of the carious process.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Caries↗
PubMed1989

Inhibition in vitro of caries around amalgam restorations by bonding amalgam to tooth structure.

Class 5 preparations in human molars were restored with amalgam. In half of the restorations, an experimental resin liner capable of bonding amalgam to tooth structure was used. The restored teeth were incubated in a bacterial medium containing sucrose and a culture of Streptococcus mutans. Artificial carious lesions were produced around all restorations. The experimental liner inhibited penetration of the lesions along the cavity wall. This inhibition was more effective at the occlusal side.

Dental Amalgam↗
PubMed1988

Bonding of amalgam to tooth structure: tensile adhesion and microleakage tests.

Amalgam can be bonded to etched enamel by a thin coat of Panavia resin cement with a resulting mean bond strength of 1404 psi to enamel and 469 psi to dentin as tested in tension. Less microleakage was observed in resin-bonded amalgam restorations than in Copal varnish-lined or unlined restorations. The technique could be used clinically with possible implications for cavity design, fracture resistance of restored teeth, and recurrent caries. These properties as well as the variables affecting bond strength need further exploration.

Acid Etching, Dental↗
PubMed1965

Comparative trial of live measles vaccines in Czechoslovakia.

The study reported in this article was conducted under the auspices of WHO as part of the Organization's programme on measles vaccination.In the spring of 1964, 416 children aged between 8 months and 3 years were inoculated with one or another of the following agents: Enders Edmonston B vaccine (alone or with gamma-globulin), Schwarz vaccine, Beckenham 20 vaccine, Milovanović vaccine, and a placebo.Seroconversion rates ranged from 91% to 100%, which indicates that the vaccines tested were highly immunogenic. The incidence of reactions was low, and from the clinical point of view acceptable. Clinical comparison of the reactions provoked by the different vaccines showed that the lowest rate was in the groups given Schwarz vaccine and Enders Edmonston B plus gamma-globulin, and the highest in the group given Beckenham 20 vaccine. However, the greater frequency of reactions observed with Beckenham 20 vaccine might have been due to the high dose given in the first stage of the trial.Complications were observed in 10 children, of whom four were in the placebo group. In three of the remaining cases a causal connexion with the vaccine could not be excluded with certainty.

Child, Preschool↗
PubMedDate not supplied

Bonding of amalgam restorations: existing knowledge and future prospects.

A number of laboratory and clinical studies over the last 15 years have explored the potential advantages of bonding amalgam to tooth surfaces. Bond strengths have been reported to range from 2 to 20 MPa, with higher bond strengths reported for filled adhesives. Most studies agree that the use of bonding results in a considerable reduction of microleakage, when compared with copal varnish or no lining. The use of bonding provides retention in vitro that is equivalent to, or better than, the use of mechanical undercuts. Most studies on strength of restored teeth report an improvement in resistance to fracture or cuspal flexing as measured by strain gauges. Penetration of secondary caries along the interface has been found to be inhibited by bonding. The mode of failure of bonded amalgams has generally been reported to be mixed, but predominantly between the resin and amalgam. In vitro studies have reported one potential problem in the incorporation of resin into amalgam, which may cause a decrease in strength of the restoration. The clinical studies of bonded amalgams that have been published to date are of short duration, indicating that when traditional preparations are used, no problems are seen with bonding, but also no advantages, as measured by clinical assessment criteria. However, some studies show that bonded amalgam may be useful for procedures where non-bonded amalgams would be expected to be lost, namely in preparations with little, if any, mechanical retention. It was concluded that, while there are various in vitro studies demonstrating that bonded amalgams have advantages of improved retention and tooth reinforcement and decreased marginal microleakage and secondary caries, the operative technique is more complicated and there are few advantages yet evident from clinical studies in conventional preparations having mechanical retentive features. However, there is evidence accruing from clinical studies that bonding of amalgam can be favorably used to extend the range of usage of amalgam to non-retentive conservative preparations, and toward the other extreme, as an adjunct to other forms of retention in large compound restorations.

Adhesives↗