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Biomedical subjects

J Geis-Gerstorfer

Publications and source records attributed to J Geis-Gerstorfer.

At least 37 records · Page 2Linked to original sources
PubMed1989

In vitro substance loss due to galvanic corrosion in Ti implant/Ni-Cr supraconstruction systems.

To characterize the galvanic corrosion of supraconstructions consisting of Ni-Cr alloys that come in contact with titanium implants, the resultant substance loss was determined. The measurement of the released substance masses was conducted by analysis of the electrolyte solutions with the aid of atomic absorption spectrometry and by approximate calculation using current density time curves, according to Faraday's law. The results of this study show that both methods allow a clear differentiation of the corrosion behavior of various Ni-Cr alloys that come in contact with titanium.

Chromium Alloys↗
PubMed1989

[Wetting of various restorative materials].

The mechanisms of varying degrees of plaque accumulation on restorative materials have not been fully clarified yet. Apart from surface morphology, interface phenomena between restorative material, saliva and microorganisms have been discussed. In this study a digital tensiometer was used to determine the degree of wetting of various restorative materials with natural saliva. The veneering material Dentacolor exhibited the highest degree of wetting, followed by dental porcelain and electrolytic gold. The non-precious metals displayed the lowest degrees of wetting. These in vitro results have been compared with the clinical behavior of the materials studied. A critical discussion is given.

Composite Resins↗
PubMed1989

[Effects of caries-preventive fluoride gels on dental ceramics].

The effects of several fluoride gels on ceramic surfaces (Dicor, Optec, Biodent ceramic and Vita VMK) were tested by SEM and by means of an electrical stylus instrument. After 10 min exposure time an acidulated gel (Oral-B Fluoride-Gel) showed a significant effect, whereas the effect of two non-acidulated gels (Elmex-Gelee, Blend-a-med Fluoride Gel) was not significant. After 24 h exposure time, Elmex and Blend-a-med gel showed an effect, too.

Dental Porcelain↗
PubMed1989

[Effect of Mo content and pH value on the corrosion behavior of Ni-20Cr-Mo dental alloys].

The results showed that the resistance against pitting corrosion in an acid milieu was dramatically improved by increasing the Mo content, while in a neutral milieu the pitting potential Ep remained unchanged. Remarkably, a Mo-content of more than 6 wt. % resulted in a further reduction in the pitting corrosion potential Ep, when pH 2 has been exceeded. A similar behaviour has been observed with the critical pitting potential Ec: Ec is also reduced at pH values between 3 and 7. To avoid pitting corrosion in the clinically relevant pH range of 4 to 7, a pitting resistance equivalent (PRE) of at least 43 is required.

Chromium Alloys↗
PubMed1989

[Profilometric studies on the surface reproduction of dental impression materials].

The reproduction of elastic impression materials is described with a laser-technique. This technique allows a quantitative evaluation without touching and deforming the surfaces. Although it is possible to measure differences, clinically relevant differences between several elastomere and one hydrocolloid material are not found.

Dental Impression Materials↗
PubMed1989

[Finishing of cast titanium for crowns and bridges].

The surface roughness of cast Titanium compared with a precious alloy (Au-Ag-Cu), two Pd-base alloys (Pd-Ag-Sn-In, Pd-Sn-Ga-Cu) and two base metal alloys (Ni-Cr-Mo, Co-Cr-Mo) was determined by surface profile measurements after polishing with six different polishing pastes. The results revealed the best surface quality for Au-Ag-Cu followed by Ni-Cr-Mo, Co-Cr-MO, Pd-Sn-Ga-Cu and Pd-Ag-Sn-In. The highest but still acceptable surface roughness was found with Ti.

Dental Alloys↗