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Biomedical subjects

M D Jendresen

Publications and source records attributed to M D Jendresen.

At least 37 records · Page 2Linked to original sources
PubMed1981

Time-dependent accuracy of elastomer impression materials. Part I: Condensation silicones.

1. Although condensation silicone elastomers can be used to produce multiple dies from a single impression, one can expect changes in dimensions of dies produced from successive pours. 2. Putty/wash systems exhibit variable behavior among different brands. Some products produce a series of dies of increasing diameter over a 4-day period, while other brands may produce a series of dies whose diameters decrease as they are successively poured. 3. Light-body wash silicone impressions made in adhesive-lined custom acrylic resin trays produce dies which increase in diameter with time. 4. Putty/wash system, in general, show a greater eccentricity of dies than is seen with custom-tray/adhesive/wash systems, but there were some significant exceptions among the brands tested. 5. There does not appear to be any difference in behavior between single-wash and double-mix techniques in the condensation-silicone systems. 6. For maximum accuracy, the condensation-silicone systems should be poured as soon as possible after making the impression.

Adhesives↗
PubMed1981

Clinical adhesiveness of selected dental materials. An in-vivo study.

An investigation was conducted to determine the clinical adhesiveness of some commonly used dental materials. Contact angle measurement data, obtained under clinical conditions, were used to calculate the in vivo-critical surface tensions for enamel, gold, stainless steel, and a resin polymer. The results of this study showed that the adhesive properties of the artificial surfaces studied were considerably modified in the oral environment. Thus, after two hours these solids with diverse original surface chemistries were observed to produce in vivo-critical surface tensions common to those recorded for enamel. The observed changes were attributed to be absorbed biofilm (acquired pellicle), which forms on all solid surfaces in the oral cavity.

Adhesiveness↗
PubMed1981

Microtopography and clinical adhesiveness of an acid etched tooth surface. An in-vivo study.

The clinical adhesiveness as expressed by the critical surface tension and roughness of an acid etched tooth surface was studied as a function of time; from time of acid "conditioning" and at selected time intervals up to seven days. The critical surface tensions of the tooth surface were calculated from clinical contact angle measurements as were values for change in roughness. SEM micrographs of the surfaces were obtained for visual comparisons. The results indicate that the surface of the tooth returns to its original state of adhesiveness and roughness in a relatively short period of time as a consequence of the adsorption of a biofilm, the acquired pellicle.

Acid Etching, Dental↗
PubMed1981

Standardization of clinical investigators for studies of restorative materials.

In preparation for internordic studies of the clinical performance of selected restorative materials, 11 clinicians from Denmark, Finland, Norway and Sweden were selected to participate in two clinical training sessions. The first of these sessions consisted of lectures on clinical research methodology, the content of a research protocol and specific description of the criteria to be used for clinical evaluation of Color Match, Cavo Surface Margin Discoloration, Anatomic Form, Margin Adaptation, and Caries. Demonstrations were also given in the clinical evaluation procedures. Using a rotation system at both the training sessions each participant alternatively served as patient recorder and examiner. The participants examined and rated a larger number of restorations independently in teams of two. The results of the performed examinations showed the overall agreement between all pairs to exceed 85%. The results of this study indicate that after a short introductory course, scientifically non-experienced senior clinicians can be trained to use the described system at a comparatively high overall level of precision.

Dental Materials↗
PubMed1980

Effectiveness of hardening films on die stone.

1. Cyanoacrylate resins and resinous die hardeners effectively improved the hardness and abrasion resistance of stone dies. 2. Application of liquid resins followed by blotting and/or blowing with compressed air produced an improved surface without clinically significant dimensional change. The extent of film buildup was qualitatively related to the viscosity of the resin. 3. Application of multiple coats of resin or simply soaking the dies in resin without further blotting or other mode of removal of the excess produced a thick film which can obliterate surface detail.

Calcium Sulfate↗
PubMed1980

Clinical adhesiveness of the tooth surface.

The clinical adhesiveness of tooth structure was determined for 43 individuals using intraoral contact angle measurements. There were no statistically significant differences in the critical surface tensions of wetting between groups of males and females nor between the three age groups tested. There was a statistically significant difference between individuals. The critical surface tensions for all the tooth surfaces measured were in the bioadhesive range of 32--50 dynes/cm. The formation of an organic film, pellicle, on the surfaces of teeth brings groups of different ages and sex to a common state of bioadhesiveness, allowing for the subsequent bacterial colonization and plaque formation as a clinical consequence.

Adhesiveness↗
PubMed1978

Micromorphologic features of cervical erosion after acid conditioning and its relation with composite resin.

The dentin surface in cervical erosion appears relatively smooth with evidence of intratubular deposits. After acid conditioning, the tubules are made patent though some still contain relatively less soluble intratubular contents. Resin applied to acid-conditioned, eroded dentin penetrated approximately 30 micrometers compared to more than 100 micrometers into the tubules of similarly treated normal dentin.

Acid Etching, Dental↗