Search PubMed⌕ Search

Biomedical subjects

E K Hansen

Publications and source records attributed to E K Hansen.

At least 55 records · Page 3Linked to original sources
PubMed1986

Effect of three dentin adhesives on marginal adaptation of two light-cured composites.

The marginal adaptation of two light-cured composites, Silux and P-30, was tested in butt-joint dentin cavities prepared in extracted human teeth. The cavity diameter ranged from 1.8 mm to 6.3 mm. Only minor differences were found between the marginal contraction gap of Silux and P-30 when used without previous application of a dentin adhesive. The light-cured Scotchbond proved to be as effective as GLUMA in reducing the contraction gaps of Silux providing the smear-layer was partly removed, the adhesive polymerized for 50 s and finally wetted with Silux Enamel Bond prior to application of Silux. Both adhesives had markedly less effect on the contraction gaps of the highly filled P-30.

Adhesives↗
PubMed1986

Surface discoloration of restorative resins in relation to surface softening and oral hygiene.

Restorative resins are susceptible to softening caused by organic acids produced in plaque. Consequently, plaque-covered resin restorations may be liable to pronounced surface staining. In the clinical part of the study a relationship between surface staining and local oral hygiene was demonstrated. This may be explained by the results from the laboratory part of the study, in which a relationship between surface staining and softening was found.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1986

Effect of cavity depth and application technique on marginal adaptation of resins in dentin cavities.

The wall-to-wall polymerization contraction of two restorative resins was investigated in butt-joint dentin cavities prepared in extracted human teeth. The cavity diameter was 4 mm, and the cavity depth ranged between 0.5 and 3.0 mm. The width of the maximum marginal contraction gap was measured, using a light microscope, approximately 0.1 mm below the original free surfaces of the fillings. It was found that increasing the cavity depth from 0.5 to 3.0 mm did not influence the marginal contraction gap close to the free surfaces of the fillings. It was also found that a two-phase application technique, where the surface of the first layer was placed parallel to the free surface of the cavity, did not reduce the marginal contraction gap, while a two-phase technique with oblique layers resulted in approximately a 25% reduction.

Acrylic Resins↗
PubMed1985

Cavity preparation for restorative resins used with dentin adhesives.

The marginal adaptation of Silux used with and without previous application of different dentin adhesives was analyzed for correlation between maximum marginal contraction gap (MG) and different combinations of one or more of the following variables: area of cavity walls (A), the total area of cavity bottom and cavity walls (B), cavity depth (h), area of cavity surface (S) and cavity volume (V). The best fit to linear regression was found with MG = a + b . V/A with the mean of the correlation coefficients being 0.907. The statistical analysis showed that in order to maintain the V/A ratio at a minimum, root caries lesions should not be prepared after excavation if the retention of the restorative resin can be ensured with an effective dentin adhesive. The greatest influence on the V/A ratio was found to be exerted by the radius of the cavity bottom; variation of the radius of the surface of the cavity also influenced the V/A ratio, but to a minor degree.

Adhesives↗
PubMed1985

Comparative study of dentin adhesives.

The marginal adaptation of Silux after application of different dentin adhesives was investigated in dentin cavities prepared in extracted human teeth. The cavity diameter ranged from 1.8 to 6.4 mm and the cavosurface angle was 90 degrees, 110 degrees, 135 degrees or 160 degrees. The investigation included the following adhesives: Clearfil, Creation 1150, GLUMA, NPG-GMA + PMDM, Palfique, Panavia, Scotchbond and Superbond. Silux Enamel Bond was used as control. The most effective adhesive was GLUMA followed by Superbond and then NPG-GMA + PMDM; Palfique, Panavia and Scotchbond were all less effective than NPG-GMA + PMDM, and both Clearfil and Creation 1150 were inferior to the control, Silux Enamel Bond. None of the adhesives were able to prevent the formation of marginal gaps when measured 10 min after polymerization. After water absorption for 1 day, only GLUMA and Superbond produced gapfree fillings. Increasing the cavosurface angle resulted in a significant improvement of the effect of all adhesives, the main reason for this being the reduced ratio volume of filling to area of cavity wall.

Adhesives↗
PubMed1984

Effect of Scotchbond dependent on cavity cleaning, cavity diameter and cavosurface angle.

The effect of Scotchbond on the wall-to-wall polymerization contraction of a visible light activated microfilled resin was investigated in cavities prepared in extracted human teeth. The cavities were cleaned either with water spray or a saturated acidic solution of EDTA, the latter giving significantly better results. The cavities were prepared with cavosurface angles between 90 degrees and 160 degrees. A highly significant improvement of marginal adaptation was found with increasing cavosurface angle.

Adhesives↗
PubMed1984

Clinical short term study of marginal integrity of resin restorations.

The marginal adaptation of 649 Durafill and Silux fillings in beveled and acid etched enamel cavities was assessed in a clinical study. The investigation included Class III with and without lingual extension, Class IV and Class V. The frequency of marginal discoloration and marginal gaps after 15 months was markedly reduced in all Classes when a low-viscous resin was used prior to application of the restorative.

Acid Etching, Dental↗
PubMed1984

Effect of five adhesives on adaptation of resin in dentin cavities.

Cylindric dentin cavities ranging from 2 to 6 mm in diameter were treated with different dentin adhesives: Clearfil, Gluma, NPG-GMA + PMDM, Scotchbond or Superbond before filling with Silux. The maximal contraction gap was measured 10 min after curing and compared with results from cavities where an adhesive was omitted. The effectiveness in reducing contraction gaps increased in the following order: Clearfil, Scotchbond, NPG-GMA + PMDM, Superbond and Gluma.

Acrylic Resins↗
PubMed1983

Effect of pressure upon wall-to-wall polymerization contraction of a chemically-cured resin.

The marginal gaps of 105 Silar fillings were measured after application of a load between zero and 100 N on the matrix during the initial polymerization. The fillings were placed in non-etched dentin cavities in extracted human teeth. The dentin surrounding the cavities was either roughened with carborundum paper No. 220 or polished with Alfa Micropolish 1 micron before the cavities were filled. When load was applied to the matrix, no effect was found of the roughness surrounding the cavities, but without load the wall-to-wall contraction was significantly greater in cavities where the surrounding dentin surfaces had been polished with Alfa Micropolish. Apparently the effect of load was related to friction during the polymerization between filling surplus and the dentin surrounding the cavities and not to load per se.

Acrylic Resins↗
PubMed1983

After-polymerization of visible light activated resins: surface hardness vs. light source.

The Wallace hardness of four visible light activated resins (Durafill, Heliosit, Silux and Visio-Dispers) was investigated at different times from 1 min and 35 s up to 60 min after start of irradiation. The prevailing part of the increase in surface hardness was found within the first few min after irradiation and this pattern was similar in all resins independent of light source.

Chemical Phenomena↗
PubMed1982

Visible light-cured composite resins: polymerization contraction, contraction pattern and hygroscopic expansion.

The wall-to-wall polymerization contraction and hygroscopic expansion of Durafill, Heliosit, Silux and Visio-Dispers were examined in dentin cavities in extracted human teeth. The linear shrinkage varied from 0.24% to 0.63% and only two of the tested materials were able to close the marginal gap owing to water absorption. The gaps were nearly always broadest in the apical part of the filings. Measurements of the marginal gaps were made at different levels between 100 and 1200 microns below the free surface of the fillings and the wall-to-wall polymerization contraction was found to increase markedly from the level of 100 microns down to 800 microns. The contraction pattern of the four light-cured resins differed significantly from the one found in a chemically-cured material.

Absorption↗