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Biomedical subjects

M Berge

Publications and source records attributed to M Berge.

26 records · Page 2Linked to original sources
PubMed1983

Bending strength of intact and repaired denture base resins.

Results of bending strength and deflection at fracture of intact and repaired denture base resin specimens were obtained. Both heat-cured and cold-cured resins of two different products were used. After storage in distilled water at 37 degrees C for 1 month, some of the intact heat-cured specimens were dried in air at 21 +/- 1 degree C for 24 h before testing. This induced a lowering of the bending strength. There was no difference in strength between the two products. However, the intact heat-cured specimens of SR 3/60 showed higher results of deflection at fracture than Vertex. Repaired specimens had a bending strength between 42.9% and 61.2% compared with the intact heat-cured specimens tested immediately after storage in water. The repair performed with the low-viscosity self-cured resin resulted in higher bending strength values than when using repair material with the higher initial viscosity. Drying the broken heat-cured specimens for 24 h at 21 +/- 1 degree C before the repair and painting with monomer liquid on the fractured surfaces of the heat-cured resin was without effect on the bending strength of the repaired specimens.

Acrylic Resins↗
PubMed1983

Liberation of copper, zinc, and cadmium from different amalgams.

Release of copper, zinc, and cadmium from six different amalgams in 0.9% NaCl solution has been registered during a 4-week period. The products showed widely different corrosion behavior. A dispersion-type amalgam released the smallest amounts of copper but the largest amounts of zinc. A product containing indium had a high rate of copper dissolution. Cadmium was liberated to a great extent from a copper amalgam. The rate of corrosion varied greatly for the different products during the time of the experiment. The liberation of copper and zinc was inversely correlated.

Cadmium↗
PubMed1982

Flexural strength of joined and intact amalgam.

Flexural strength of joined and intact specimens of five different alloys were measured. The same alloys were also tested in compression. Joined specimens were also tested in compression. Joined specimens were made by condensing fresh amalgam against the ground surface of 1 week old amalgams. Joined specimens had a flexural strength between 11.5% and 51.4% compared to the intact specimens. The high copper alloys obtained the lowest values for fracture toughness and plastic strain when tested in compression. A positive correlation was shown between flexural strength of joined specimens and plastic strain and between flexural strength of intact specimens and fracture toughness.

Chemical Phenomena↗
PubMed1982

Corrosion of silver soldered orthodontic wires.

The amounts of metals liberated from silver soldered stainless steel and cobalt-chromium orthodontic wires were measured. Measurements were taken after 3 days and 24 days immersion in 0.9% sodium chloride solution. High amounts of copper and zinc and some cadmium from the silver solder were found. The silver soldered stainless steel wire corroded more than the cobalt-chromium type, and liberated more nickel and chromium than did the cobalt-chromium wires.

Chemical Phenomena↗
PubMedDate not supplied

The pattern and severity of wear of resin facings in fixed prosthetic restorations in vivo.

Wear of prosthodontic resin facings in 176 metal-resin canine crowns and retainers for fixed partial dentures was studied in clinical photographs and assessed using a graded scale. Four cross-sectional groups of restorations were studied according to length of clinical service (1, 3, 6, and 9 years). The criteria used during the examination described loss of substance in relationship to the metal cast framework. The method was tested for reliability and consistency. The results showed that the extent of wear increased with increasing time of clinical service (P less than .05). More severe wear scores were assigned to restorations in female patients than to those in male patients (P less than .05), to the mandibular facings compared to those in the maxillae (P less than .05), and the incisal areas of the facings compared to the cervical areas (P less than .05). Patients instructed in oral hygiene measures tended to show more severe wear than noninstructed individuals. A significant association was established between the ratio of vertical and horizontal overlap and the wear scores. Increasing VO/HO ratios seemed to be accompanied by increasing wear.

Chi-Square Distribution↗