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Biomedical subjects

W Geurtsen

Publications and source records attributed to W Geurtsen.

At least 19 recordsLinked to original sources
PubMed1992

Human cell culture studies with dental metallic materials.

The compatibility of cast non-alloyed titanium and eight dental castable alloys (precious, low noble, non-precious) was determined by means of human primary oral fibroblasts derived from the attached gingiva and the periodontium. Furthermore, cast non-alloyed Ti was tested in a human permanent cell culture (MOLT 4). All investigated metallic materials showed cytotoxic properties in primary cultures. The differences in cytotoxicity between the various materials were statistically significant. The best results were found for one noble alloy and for non-alloyed titanium, whereas all non-precious alloys almost completely inhibited cell growth. The cytotoxic potential of the investigated materials might contribute to the irritating effect of dental cast restorations adjacent to the gingiva and the periodontium.

Biocompatible Materials↗
PubMed1992

The cracked-tooth syndrome: clinical features and case reports.

Over a period of 5 months, 18 patients with one or more cracked teeth were treated. Mandibular first molars and maxillary premolars were the teeth most frequently affected. The least affected teeth were mandibular premolars. Predisposing factors for cracked-tooth syndrome are decreased stability (such as caries or poor cavity design) and overloading of the tooth. Treatment involves initial reinforcement and a circumferential cast restoration.

Adult↗
PubMed1991

[Study on the residual monomer contents of different light curing hybrid composite resins].

In this study the methanol and aqueous extracts of four modern light-curing hybrid composite resins (unpolymerized and polymerized) were examined for eluable organic components by means of gas chromatography/mass spectroscopy. All substances found in the methanol extracts of the unpolymerized specimens were identified in the elutions of the cured materials too. Furthermore, all cured specimens contained at least one additional eluable component created during polymerization. In each composite resin there was at least one extractable substance which is classified as toxic.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1991

[Fracture resistance of human premolar with regard to morphological factors].

173 extracted human upper and lower premolars were tested for their fracture resistance with regard to the morphological factors proximal vertical fluting and occlusal abrasion. Upper and lower premolars revealed a comparable fracture strength. The proximal groove did not influence the fracture resistance. Markedly abraded teeth showed a higher fracture strength than premolars without or with only a moderate occlusal abrasion. But these differences were not significant statistically. In total the morphological factors, which were considered in this study, should not influence the fracture resistance.

Bicuspid↗
PubMed1990

[Use of titanium in conservative dentistry].

Non alloyed titanium is characterized by an excellent resistance to corrosion, a relatively low thermal conductivity, a good ductibility and biocompatibility. Furthermore the costs for this material are very low. First clinical experiences with respect to inlays, onlays, partial and full crowns fabricated out of this metal can be classified as positive. Problems in processing cast titanium (e.g. reduction of the material, polishing) should be solved by the development of special instrument sets.

Crowns↗
PubMed1990

[Investigation of accuracy of fit of partial crowns with different shaped margins].

The marginal adaptation of partial crowns with different types of finish line preparations was determined by means of dye penetration tests. The best marginal sealing was found for the featheredge-like preparation, followed by the shoulder preparation and the chamfer preparation with or without bevel. The scanning electron microscopic evaluation revealed that a finishing of the restoration margins during the setting of the luting material resulted in a better marginal sealing than a finishing after the cementation.

Adult↗
PubMed1990

[Studies of the bond of two different types of composites to etched enamel].

The strength of the bond between a microfilled or, respectively, a hybride composite and acid-etched enamel was examined in a shear test and by SEM in human teeth after different modes of preparation. The results showed that the best bond strengths were obtained with microfilled resin without use of a bonding agent. The retention of the hybride composite was better in combination with a bonding agent. Mechanical reduction of the enamel increased the bond strengths of all tested materials.

Acid Etching, Dental↗
PubMed1990

[Crown and restoration margins].

The marginal quality of a crown or a filling is of great importance for the success or failure of any restoration. Secondary caries and a marginal periodontal disease are the result of defects in this very critical area. This should be mainly caused by a plaque accumulation, which is determined by the adaptation, the contour, the placement and the quality of the surface of the restoration margin. With respect to the irritation of the marginal periodontium specific cytotoxic effects of each material might be a cofactor too.

Crowns↗
PubMed1989

[Fracture resistance of human maxillary molars with MOD amalgam or composite fillings].

The fracture resistance of human maxillary molars was tested following different types of cavity preparation and filling with various materials. The untreated controls and teeth treated with amalgam/Dentin Adhesive showed the highest strength values. A comparable fracture resistance was found in teeth with amalgam or composite fillings and direct composite inlays, these values being significantly lower than in the controls. The lowest strength values measured were those of the unfilled teeth with prepared cavities.

Composite Resins↗