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Biomedical subjects

E C Munksgaard

Publications and source records attributed to E C Munksgaard.

At least 55 records · Page 3Linked to original sources
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

Dentin-polymer bond established by Gluma and tested by thermal stress.

The walls of cylindrical cavities in human dentin were treated with Gluma and various resins before filling with either a microfilled or a macrofilled composite (Silux, P-30 or Concise). The extent of gaps (crevices) along the tooth/filling interface was observed before and after thermal cycling at restorations polished either 10 min or 24 h after curing of the composite. Application of a resin containing polymerization initiators and 1% propanal before filling with Silux or Concise resulted in restorations without contraction gaps along the tooth/filling interface. When P-30 was used in this procedure, one of six of the fillings exhibited gaps, but none of the six did so when removal of the marginal excess was postponed for 24 h.

Aldehydes↗
PubMed1987

Wall-to-wall polymerization contraction of composite resins versus filler content.

Various amounts of microfiller, condensed microfiller, prepolymer plus microfiller, or macrofiller were added to an unfilled light-curable resin. The marginal adaptation of these experimental resin/filler mixtures was studied by measuring the wall-to-wall polymerization contraction (wtw-contraction) in dentin cavities in vitro. The investigation showed that increasing amounts of microfiller did not affect the wtw-contraction. However, mixtures made by the three other fillers showed a decreasing wtw-contraction with increasing filler concentration.

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

Composite wall-to-wall polymerization contraction in dentin cavities treated with various bonding agents.

Extracted human teeth are frequently used in studies on bonding of composites to dentin. However, little is known about the effect of storing conditions on the results recorded. The purpose of the present work was to measure the wall-to-wall polymerization contraction of a light-cured composite material with and without the use of five different dentin bonding agents in cylindrical dentin cavities prepared in extracted human teeth, either fresh or after storing for up to 4 wk in four different media. No effect of the storing conditions on the width of contraction gaps could be demonstrated when the teeth were stored in tap water or in a 1.0% aqueous chloramine solution. Aqueous solutions of either 0.1% benzalkonium chloride or 0.9% sodium chloride did occasionally affect the size of the contraction gap.

Adhesives↗
PubMed1985

Effect of combining dentin bonding agents.

The wall-to-wall polymerization contraction of a light-cured composite was measured in cylindrical dentin cavities treated with the bonding agents: Scotchbond, Clearfil Bond, Gluma/Scotchbond, Gluma/Silux Enamel Bond or Gluma/Clearfil Bond. Marginal gaps were prevented in 29 out of 30 cases when Gluma was used in combination with Clearfil Bond. This combination mediates a mean bond strength between composite and dentin of 20 MPa.

Adhesives↗
PubMed1985

Dentin-polymer bond in resin fillings tested in vitro by thermo- and load-cycling.

The effect of stress applied by thermo- and load-cycling to the bond between composite- and bonding-agent-treated dentin was tested. Cylindrical cavities in extracted human teeth, approximately one-half of the margins in dentin, were etched and treated with two bonding agents - Gluma and Clearfil Bond - before being filled with Silux composite. Forty specimens, some provided with cavity floor lining, were cycled several hundred times between 15 degrees and 50 degrees C, either immediately after light-curing or upon 24 hr of water storage. In all cases, microscopic inspection revealed unchanged adaptation at the dentin margins. Teeth with Class 3 and Class 5 cavities, ten of each and with the gingival margins entirely in dentin, were pre-treated and filled as above. The teeth were covered with a dye during loading and unloading in a manner simulating biting and chewing. Inspection of the cavity margins revealed absence of percolation at the dentin margins. It is concluded that effective bonding agents are necessary to prevent contraction gaps in resin-filled cavities where the margins are partly or entirely located in dentin.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1985

Dentin-polymer bond promoted by Gluma and various resins.

Gluma-treated dentin was covered with various resins before a microfilled composite was applied. The strength of the bond between dentin and composite established by this procedure was measured in shear and tensile tests. The effectiveness of the bonding was further tested by the width of the marginal contraction gap around fillings made in dentin by the above procedure. Resins containing propanal promoted shear bond strength of about 15 MPa. The tensile bond strength exceeded 22 MPa by one of the resins, but could not be measured because of frequent rupture in the composite. Between 30 and 70% of the fillings were without contraction gaps when propanal or p-toluenesulfinate-containing resins were used. It is proposed that oxygen inhibition of the polymerization on the dentin surface suppresses the bonding. Resins containing reducing agents may reduce oxygen inhibition and increase bonding by the adhesive.

Aldehydes↗
PubMed1985

Bonding of restorative resins to dentine promoted by aqueous mixtures of aldehydes and active monomers.

Effective bonding between restorative resins and hard dental tissues would eliminate the need for retentive undercuts and prevent the formation of marginal gaps. While bonding to enamel has found a satisfactory solution with the advent of the acid etch technique, bonding to dentine has been more elusive. Restorative resins may bond to dentine through mechanisms involving either the inorganic or the organic constituents of the dentine. In the present work the possibility of bonding to the organic part of dentine was investigated. Since the water present in the surface of moist dentine may impede bonding, the research was focused on adhesives that are operational in aqueous environments. Aqueous mixtures of aldehydes and certain active monomers constitute such adhesives. The strength of the bond between a restorative resin and dentine was measured using the mixtures as intermediaries. To remove the smear layer the dentine was pretreated with 0.5 M EDTA, pH = 7.4. Among the aliphatic aldehydes especially propionic aldehyde and glutaraldehyde were found to be effective. Aromatic aldehydes resulted in bonds of low strength. Among the monomers investigated HEMA (hydroxyethyl-methacrylate) gave rise to the bond of highest strength. Using an adhesive based on HEMA and propionic aldehyde or HEMA and glutaraldehyde bond strengths of 15 and 18 MN/m2, respectively, were obtained. The latter adhesive significantly reduced the width of the polymerization contraction gaps between resin and dentine.

Aldehydes↗
PubMed1984

Formaldehyde as bonding agent between dentin and restorative resins.

The bonding of restorative resins to dentin by means of formaldehyde used in conjunction with an OH-containing monomer as intermediary was investigated. In this way a bonding to the organic constituent of dentin is conceivable. Mean bond strengths of 0.6 kg/mm2 were obtained. Bond strengths of this order of size may be of clinical interest.

Dental Bonding↗
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↗
PubMed1984

Bond strength between dentin and restorative resins mediated by mixtures of HEMA and glutaraldehyde.

We investigated the bond strength between restorative resin and dentin pre-treated with mixtures of HEMA and glutaraldehyde. It is suggested that the mixture acts by forming a chemical bond of HEMA molecules to a collagen-glutaraldehyde reaction complex. Subsequently applied resin will then co-polymerize with the collagen-linked methacrylate groups. Statistical analysis of the results from varying mixtures of HEMA and glutaraldehyde revealed that the bond strength was highly dependent on the HEMA concentration, with a maximum at 35%, and nearly independent of the glutaraldehyde concentration when greater than 3%. The highest mean bond strength was about 1.8 kg/mm2, and bond strength of this order of size may be attractive for clinical use.

Acrylates↗