Search PubMed⌕ Search

Biomedical subjects

E Asmussen

Publications and source records attributed to E Asmussen.

At least 109 records · Page 6Linked to original sources
PubMed1988

Influence of dentin-bonding agents and a glass-ionomer base on the cervical marginal seal of Class II composite restorations.

The cervical dentin marginal seal of Class II composite resin restorations was assessed in vitro. Elimination of marginal contraction gaps by specific dentin-bonding treatments led to a reduction in the extent of cervical microleakage as assessed by a silver staining method. The use of a "sandwich" technique employing a glass-ionomer material to seal the cervical cavity margin did not prevent cervical microleakage occurrence.

Chemical Phenomena↗
PubMed1988

Bonding of restorative resins to dentine: status of dentine adhesives and impact on cavity design and filling techniques.

In conjunction with the acid etch technique for bonding of restorative resins to enamel, an effective bonding to dentine would eliminate the need for retentive undercuts and ensure a tight marginal seal. Bonding to dentine can be achieved through dentine adhesives. These may be divided into Ca2+-bonding and collagen-bonding types. Several Ca2+-bonding adhesives are based on phosphate methacrylates. Adhesives of this type mediate a bond strength to dentine not exceeding 10 MPa. In contrast, Bowen's bonding system and the Gluma system yield bond strengths higher than 10 MPa. The two latter systems have recently been conceived in simplified versions. In general, the higher the bond strength to dentine mediated by an adhesive, the smaller are the marginal gaps formed by a composite resin polymerizing in a dentine cavity treated by the adhesive. The size and the shape of the cavity influence the width of the marginal gaps. A cavity having a V-shape gives rise to smaller gaps than box-shaped cavities. A filling technique with two 'inclining' layers reduces the width of marginal gaps. Combination of certain Ca2+-bonding and collagen-bonding adhesives results in increased bond strength and smaller marginal gaps.

Adhesives↗
PubMed1987

Influence of temporary filling materials on effect of dentin-bonding agents.

Dentin cavities, prepared in extracted human teeth, were filled with a dry mixture of zinc oxide-eugenol (ZOE) or a commercial temporary filling cement without eugenol (Cavit). The ZOE was removed 3 h later while the Cavit was removed after 7 days. The cavity wall and the surrounding dentin were then treated with a dentin-bonding agent before application of a restorative resin. The width and the extent of the marginal contraction gap were measured, using a light microscope, approximately 0.1 mm below the original free surface of the filling. It was found that the contraction gap was markedly increased in cavities previously filled with ZOE while the non-eugenol cement had no influence on the effect of the two dentin-bonding agents tested. The short-term test applied in the present study indicates that ZOE should not be used in cavities later to be restored with dentin-bonding agent and resin.

Adhesives↗
PubMed1987

Adhesion to dentin mediated by Gluma: effect of pretreatment with various amino acids.

Dentin surfaces were treated with various amino acids. The treatment caused an alteration of the dentin surface that influenced the tensile bond strength to a restorative resin obtained with the Gluma system. The bond strengths varied between 5.6 and 14.2 MPa. Among the amino acids tested, N-phenylglycine produced the strongest bonds.

Adhesiveness↗
PubMed1987

Effect of acidic pretreatment on adhesion to dentin mediated by Gluma.

Tensile bond strengths between dentin and a typical restorative resin were measured after the dentin was treated with Gluma. Solutions of phosphoric, pyruvic, nitric, or oxalic acid, also containing various amino acids, were used as pretreatments. Without amino acids in the solutions, the pretreatments conferred bonds of low strength. Use of acidic solutions containing glycine or N-phenylglycine was found to give bonds of high strength to both dentin and enamel.

Acid Etching, Dental↗
PubMed1987

Dentine and enamel bonding agents.

Previous studies have shown that sequential use of aqueous FO (ferric oxalate containing a small concentration of HNO3), acetone solutions of NPG (N-phenylglycine), and PMDM (the reaction product of pyromellitic dianhydride and 2-hydroxyethylmethacrylate) yields strong adhesive bonding of composite resins to both dentine and enamel. The purpose of this study was to determine if aluminum ions could be substituted for ferric ions and if the procedure could be simplified. Aqueous solutions containing aluminum oxalate and aluminum nitrate, followed in sequence by acetone solutions of NPG and PMDM, gave strong tensile adhesive bond strengths between a composite and extracted human teeth. Comparable values have been obtained with FO, NPG and PMDM. Aluminum oxalate solutions containing no nitrate gave lower bond strengths, as was the case with FO. Aqueous solutions of acidified aluminum oxalate can dissolve NPG, thereby allowing a simplification of the procedure. Tested for comparison, commercially available dentine bonding agents gave lower average bond strengths on dentine than did some of the experimental materials.

Aluminum↗
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↗
PubMed1985

Dentin-polymer bond mediated by glutaraldehyde/HEMA.

A restorative resin was bonded to EDTA-treated dentin by means of a mixture of glutaraldehyde and HEMA. The bond exhibited a tensile strength of 17.5 +/- 1.0 MPa (mean +/- SEM) and was unaffected by water storage at 37 degrees C for up to 6 months. The glutaraldehyde/HEMA mixture was found to be most effective when the pH was between 2 and 5; an application time of 10 s was found to be sufficient for the glutaraldehyde/HEMA mixture as well as for the EDTA-solution.

Acrylates↗
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↗