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Biomedical subjects

C M Schoenfeld

Publications and source records attributed to C M Schoenfeld.

12 recordsLinked to original sources
PubMed1990

Performance of seven rapid radiographic processing solutions.

This study evaluated the performance of seven rapid radiographic processing products. A conventional automatic processing solution was evaluated as a standard of comparison. The products were analyzed with respect to image quality and speed. The results indicate that rapid manual processing generally involves some compromise of image quality as well as slower speeds with an accompanying increase in patient radiation exposure. Accordingly, there seems to be little motivation for the use of rapid manual processing solutions unless there is a compelling rationale in terms of time or convenience.

Emulsions↗
PubMed1987

Radiopacity of light-cured posterior composite resins.

Radiographic images of teeth and restorations were used to evaluate the radiopacity of 11 light-cured posterior composite resins. The radiopacity of these composite resins provided enough variation on radiographs so that clinicians distinguished the images of the restoration from adjacent tooth structure.

Aluminum↗
PubMed1981

The tooth-amalgam interaction.

The interaction between tooth and amalgam during in vitro corrosion of dental amalgams has been studied in this investigation. Extracted teeth have been restored with five commercial amalgams, one of which was gamma 2 -free and the others contained the gamma 2-phase. The restored teeth were immersed in a 1% NaC1 solution for 9 months. Post corrosion restorations have been examined by optical microscopy, scanning electron microscopy, and X-ray microanalysis. The results are: (1) gamma 2-containing amalgam surfaces were covered with Ca-Sn-P-rich corrosion products of various morphology which occasionally contained relatively low concentrations of C1 and/or Zn; (2) the corrosion products on the gamma 2-free amalgam surface indicated relatively high concentrations of Hg in addition to Ca, p, Sn, Cu, and Zn. These results agree with the past observations that corrosion of amalgam restorations is not an isolated process. Rather it may involve reactions of the restoration and the surrounding oral environment including tooth and oral fluids in which interactions of Sn, Zn, Hg, Ca and P take place.

Calcium↗
PubMed1979

Monomer release from methacrylate bone cements during simulated in vivo polymerization.

The release of monomer from methylmethacrylate bone cements was studied during immersion in an aqueous environment intended to simulate in vivo polymerization of the material. Monomer release from disk-shaped specimens into an aqueous environment was assayed by gas chromatography. The simulated intracorporal polymerization was carried out under a variety of conditions intended to encompass possible clinical variables. The majority of monomer release occurred within the first 15 min of immersion. Under conditions generally recommended for commercial cements the release into aqueous media was always less than 3% of the total monomer weight. Clinically feasible options of delaying the time from onset of mixing of the cement to insertion into the host resulted in only a 0.7 wt % difference in the amount of released monomer. Measurements for a variety of monomer/powder ratios demonstrated a minimum in the amount of released monomer at a ratio of about 0.4 ml/g. In terms of unit area covered, thin specimens released less monomer than thick specimens.

Bone Cements↗
PubMed1977

Scanning electron microscopy of human dental pellicle and initial plaque formation in vivo.

Small, specially prepared gold alloy discs were recessed into the right and left posterior surfaces of duplicate maxillary dentures. At selected time intervals, a disc was removed from each side of the denture and prepared for examination with a scanning electron microscope (SEM). A thin, peeling film of pellicle was seen on the discs removed after two hours and projections designated "hemispherical globules" formed on the pellicle within the next seven hours.

Bacteria↗
PubMed1977

Computerized prediction of optical density for diagnostic radiology.

A computer program was formulated and verified experimentally to predict the optical density on an image receptor for any given set of radiographic variables including tube kilovoltage, milliamperage, and wave form; x-ray beam filtration; nature of filters and absorbers, and type of x-ray film.

Absorption↗
PubMedDate not supplied

Study of in vivo plaque formation.

The technique of accumulating plaque on removable disks in a complete denture provides a convenient method for investigating plaque on artificial surfaces. Examination of the plaque specimen with a SEM indicated that the plaque consists of microorganisms and a nonstructured matrix. This technique provides results that are consistent for a given individual. However, a group of 12 different individuals had a wide range in the thickness and content of plaque accumulations during equal time intervals. Thin plaque accumulations consisted of a filmlike layer with an apparently small number of microorganisms. Thick layers of plaque consisted of relatively large numbers of microorganisms with some intercellular matrix. The thickness of the plaque layer is apparently determined primarily by the number of microorganisms present.

Aged↗