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Biomedical subjects

L Forsten

Publications and source records attributed to L Forsten.

At least 37 records · Page 2Linked to original sources
PubMed1980

Sealing of preventively enlarged fissures.

The occlusal fissures of 156 permanent first molars in 63 children, 7--8 years of age, were sealed with a chemically polymerizing material (Delton). Deep and narrow fissures were opened up with a pointed diamond before etching and sealing. The treatment was performed by untrained dental students. The patients were called back for treatment every 6 months. 2/3 of the patients were followed up for a period of 2 1/2 years. After that period the retention of sealants was 93% (74 sealants) in ground deep fissures and 88% (28 sealants) in unground shallow fissures.

Acid Etching, Dental↗
PubMed1978

Marginal leakage and consistency of the composite resin material in etched cavities.

The purpose of the study was to evaluate the degree of adaptation of undiluted and diluted composite resin to etched enamel walls with and without an intermediary resin. Cavities (O = 2 mm) were drilled in extracted teeth and the walls were etched with phosphoric acid. Fillings were made of Concise composite resin, without applying an intermediary resin (1), after applying the resin layer (2), after diluting the mix with one (3) or two (4) drops of catalyst resin but without an intermediary resin, and after diluting the mix and applying the resin layer (5). The fillings were ground flush with the tooth surface and the teeth were cycled thermally between two dye solutions baths. The marginal penetration of the dye was evaluated by measuring the discoloured portion of the margin at different depths using a stereomicroscope. The restorations with an intermediary resin (2 and 5) exhibited significantly less leakage than fillings without the intermediary layer (1, 3 and 4). When no resin layer was applied the dilution of the mix seemed to reduce the leakage compared with undiluted material but the differences were not statistically significant. The results indicate the advantage of using an intermediary resin with etching even when the composite is diluted.

Acid Etching, Dental↗
PubMed1977

Working time and strength in relation to consistency of composite resins.

Composite resin pastes can be made more fluid for injection purposes by adding small amounts of enamel bond resin before mixing. The aim of this work was to study the influence of the added resin on the working time and on the early and final strength of the composite. The pastes of two different brands diluted with their respective resins and the working time of the mix was determined by measuring the time during which it was possible to squeeze the material from a Centrix syringe. The results revealed that adding universal resin reduced the working time of both brands. The catalyst resin increased the working time of Adaptic but with Concise the amount of the catalyst paste had also to be increased to gain more working time. Adding catalyst resin did not affect the early strength or the strength after 24 h. Furthermore, it was observed that adding resin reduced the amount of porosities in the composite.

Composite Resins↗
PubMed1977

Fluoride release from a glass ionomer cement.

The release of fluoride from a glass ionomer cement (ASPA) was compared with that from a silicate cement. Test specimens were shaken in a solution with hydroxyapatite for 7 weeks. The solution was changed every week and the fluoride taken up by the hydroxyapatite measured. The specimens released considerably more fluoride during each of the first 2 weeks than during each of the subsequent 5 weeks. The continued release did not decrease very much with time. Slightly more fluoride was released from the glass ionomer cement than from the silicate.

Dental Cements↗
PubMed1977

Effect of a Ca(OH)2 solution and a chlorhexidine based detergent on the microbial activity of human carious teeth.

Occlusar carious lesions from human molars, preserved in continuous humidity after extraction, were removed using conventional clinical techniques. Bacteriological samples were taken after rinsing the cavity with water only, after experimentally infecting the cavity and after treating uninfected cavities either with a saturated Ca(OH)2 solution or with a chlorhexidine based detergent. The samples were cultivated on blood agar plates aerobically and anaerobically. Cavities rinsed with water only showed very sparce bacterial growth. After experimental infection the growth was significant, but decreased radically after treatment with the test materials. In order to describe the effect of the two test materials on the microbial enzyme activity in infected dentin, cryostat sections of 10 micrometer were prepared from undermineralized carious dentin fragments excavated from freshly extracted human teeth. Conventional histochemical techniques were applied to demonstrate the aminopeptidase activity in the sections using N-L-leucyl-2-naphthylamide as a substrate. The aminopeptidase activity of carious dentin was inhibited totally with the Ca(OH)2 solution, whereas the chlorhexidine based detergent had no effect on the enzyme activity.

Aminopeptidases↗
PubMed1976

Fluoride release from a fluoride-containing amalgam and two luting cements.

The release of fluoride from an amalgam and two luting cements, silicophosphate and polycarboxylate, was studied by shaking test specimens in a solution with hydroxyapatite, and measuring the fluoride taken up by the apatite. The initial release was significant for all three materials. After 1 week the amalgam released only minor amounts of fluoride, whereas the cements continued to liberate fluoride during the 5-week observation time to the same extent as silicates in earlier studies.

Dental Amalgam↗
PubMed1976

Fluoride uptake from restorative dental materials by human enamel.

The purpose of the study was to determine the uptake in vitro of fluoride from restorative materials by tooth enamel and whether prior etching of the enamel causes a change of uptake. The outermost layer of the labial surface of extracted canines was removed by grinding and the enamel was covered with five different fluoride-containing materials; a silicate, a composite resin, an amalgam, a silicophosphate, and a polycarboxylate luting cement. The material was either removed immediately or after storing the tooth in distilled water. The fluoride content was determined using a sensitive physical method based on the 19F (p,alpha gamma) 16 O reaction. In addition, the fluoride content of enamel after etching for different periods of time and of etched enamel which had been in contact with silicate cement was determined. The mean fluoride content of uncovered interior enamel was 226 parts/10(6). All materials, except the composite, increased clearly the fluoride content of the underlyaing enamal. Etching of interior enamel also increased the fluoride values. No difference could be shown in fluoride uptake from silicate and composite resin between etched and unetched enamel.

Acid Etching, Dental↗
PubMed1976

Marginal fracture of dental amalgams.

The purpose of this study was to determine the marginal fracture of different amalgams, using a semiclinical method which facilitates standardization and minimizes the observation time, in 10 patients receiving complete dentures. Cavities were cut occlusally in acrylic premolars and molars. The margin was then beveled to 45 degrees with a cone-shaped diamond. Two dispersion-strengthened amalgams and one conventional amalgam were used in each mouth. The cavities of each quadrant were filled with the same amalgam. Thus, conventional amalgam fillings were always placed in opposing quadrants to those filled with a dispersion-strengthened amalgam. The degree of marginal fracture was evaluated from the prints (magnification X 5-7) by five dentists separately and blindly. After 6 months' service, severe marginal fracturing was frequently seen.

Acrylic Resins↗
PubMed1975

Sealing properties of intermediary bases and effect on rat molar pulp.

Five "cream-like" intermediary bases (Hypocal¿, Dycal¿, Reocap¿, Cavitec¿ and Dropsin¿) were studied using ZnO-eugenol (ZOE) and phosphate cement for comparison. The in vitro experiments, which were designed to reveal the penetration of a dye and an etching liquid, showed that Dropsin and Hyypocal were permeable to dye and that Dropsin was permeable to acid as well. The in vivo experiments revealed no definite differences between the different cream-like base materials, nor were there differences between those and the conventional cements. The overall mildness of the dentin-pulp reactions and the suitability of the rat molar for this kind of research are discussed.

Animals↗