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G Sjögren

Publications and source records attributed to G Sjögren.

25 records · Page 2Linked to original sources
PubMed1988

Laser welding of titanium in dentistry.

Unalloyed titanium of the quality used for osseointegrated implants by the method of Brånemark is also sometimes used for the metallic part of the prosthetic superstructure placed on the fixtures and for crowns and bridges of conventional type. Forty bars of titanium, 8 of ASTM B 348 grade-1 quality and 32 of ASTM B 348 grade-2 quality, were laser-welded, using dissimilar laser joint variables. Tensile strength, 0.2% proof stress, and percentage elongation of the welded bars were measured and compared with the corresponding values for the titanium bars as delivered and with those of brazed type-3 gold alloy bars of similar dimensions. The type of fracture was evaluated from fractographs. The results showed that the use of certain defined laser joint variables during welding produced values for the mechanical properties studied which were more favorable than those obtained from the brazed gold bars. The fracture of the titanium specimens was ductile, with dimples occurring at the fracture surfaces.

Dental Alloys↗
PubMed1987

Relationship between compressive strength and cervical shaping of the all-ceramic Cerestore crown.

The two types of cervical shaping recommended for the preparation of Cerestore crowns are shoulder or deep chamfer. 14 specimens shaped like stylized Cerestore crowns on a shoulder preparation and 14 on a deep chamfer preparation were produced. Thereafter each crown was placed on the epoxy resin die on which it had been produced. 7 epoxy dies from each of the two series were shortened 1 mm occlusally in order to elucidate the importance of the cervical shaping. Placed on its own epoxy die each of the 28 Cerestore crowns was then subjected to occlusal stress until fracture occurred. The force needed for fracture was three times greater for the crowns produced on a shoulder preparation than for those produced on a chamfer preparation. No significant differences was obtained when crowns with the same cervical shaping were tested on intact and shortened dies respectively.

Aluminum↗
PubMed1983

Influence of supply of heat to cobalt-chromium frameworks during soldering and subsequent hardening heat treatment of wrought clasps.

Retentive clasp arms of wrought gold alloy wire were soldered to frameworks made of three dental cobalt-chromium alloys. The clasps were then subjected to a conventional hardening heat treatment. Microstructure and hardness of the cobalt-chromium alloys were determined before and after these operations. The results reveal that the supply of heat during soldering and hardening heat treatment of the clasp does not influence the microstructure and hardness of the cobalt-chromium alloys.

Chromium Alloys↗
PubMed1982

The cytology of joint exudates in rheumatoid arthritis. Morphology and preparation techniques.

The cytology of joint exudates from patients with rheumatoid arthritis was examined by preparation of air-dried smears; a procedure that involved cytocentrifugation of synovial fluids following dilution in a balanced salt solution containing albumin. This procedure provided a monolayer of homogeneously distributed exudate cells with excellent preservation of morphological details. The dominant cell type in the exudates was polymorphonuclear leukocytes, often with signs of necrobiosis. The small and medium-sized mononuclear cells were lymphocyte-like and vital-looking. The large mononuclear cells displayed signs of extensive phagocytosis, especially phagocytosis of polymorphonuclear leukocytes. It is suggested that the granulocytes of the synovial fluid are cells which have reached their function compartment, where they work and die.

Arthritis, Rheumatoid↗
PubMedDate not supplied

Clinical examination of leucite-reinforced glass-ceramic crowns (Empress) in general practice: a retrospective study.

PURPOSE: The purpose of this study was to retrospectively evaluate leucite reinforced-glass ceramic crowns (Empress) placed in patients who regularly visit general practices. MATERIALS AND METHODS: One hundred ten Empress crowns, placed in 29 patients who visited a general practice on a regular basis, were evaluated according to the California Dental Association's (CDA) quality evaluation system. In addition, the occurrence of plaque and certain gingival conditions was evaluated. All crowns were luted with resin composite cement. The mean and median years in function for the crowns were 3.6 and 3.9 years, respectively. RESULTS: Based on the CDA criteria, 92% of the 110 crowns were rated "satisfactory." Eighty-six percent were given the CDA rating "excellent" for margin integrity. Fracture was registered in 6% of the 110 crowns. Of the remaining 103 crowns, the CDA rating excellent was given to 74% for anatomic form, 86% for color, and 90% for surface. No significant differences (P > 0.05) were observed regarding fracture rates between anterior and posterior crowns. With regard to the occurrence of plaque and bleeding on probing, no significant differences (P > 0.05) were observed between the Empress crowns and the controls. CONCLUSION: Most of the fractured crowns had been placed on molars or premolars. Although the difference between anterior and posterior teeth was not statistically significant with respect to the fracture rates obtained, the number of fractured crowns placed on posterior teeth exceeded that of those placed on anterior teeth. The difference between the fracture rates may have clinical significance, and the risk of fracture has to be taken into consideration when placing crowns on teeth that are likely to be subjected to high stress levels.

Adult↗