In vitro lifetime of dental ceramics under cyclic loading in water.

All-ceramic dental restorations exhibit enhanced esthetics and biocompatibility as compared to traditional metal-based prosthesis. However, long-term fatigue and subcritical crack growth in the presence of water and cyclic loading can decrease the strength of ceramic components over time. We investigated the cyclic fatigue in water of three dental materials currently used as frameworks in all-ceramic restorations: a 3 mol%-yttria partially stabilized zirconia (3Y-TZP, Cercon, Degudent GmbH), a Al(2)O(3)-ZrO(2)-Glass composite (Inceram-Zirconia, Vita Zahnfabrik GmbH) and a Li(2)O.2SiO(2) glass ceramic (Empress 2, Ivoclar Vivadent AG). Fatigue and fast fracture tests were performed to determine the Weibull distribution of lifetime and initial mechanical strength for each framework component. In spite of its noticeable susceptibility to fatigue in water, the 3Y-TZP material was found to be particularly suitable for the preparation of posterior all-ceramic bridges due to its high initial mechanical strength. Guidelines are provided for the selection of materials and the design of all-ceramic posterior bridges exhibiting lifetime longer than 20 years under severe wet and cyclic loading conditions.

Law and public health at CDC.

Public health law is an emerging field in U.S. public health practice. The 20th century proved the indispensability of law to public health, as demonstrated by the contribution of law to each of the century's 10 great public health achievements. Former CDC Director Dr. William Foege has suggested that law, along with epidemiology, is an essential tool in public health practice. Public health laws are any laws that have important consequences for the health of defined populations. They derive from federal and state constitutions; statutes, and other legislative enactments; agency rules and regulations; judicial rulings and case law; and policies of public bodies. Government agencies that apply public health laws include agencies officially designated as "public health agencies," as well as health-care, environmental protection, education, and law enforcement agencies, among others.

Reliability and strength of all-ceramic dental restorations fabricated by direct ceramic machining (DCM).

All-ceramic dental bridges for the molar region are not yet available at reasonable costs. The novel direct ceramic machining (DCM) process allows an easy, reliable and rapid fabrication for all-ceramic dental restorations with high mechanical strength and good biocompatibility. In DCM, an enlarged framework is easily milled out of a pre-fabricated porous ceramic blank made of zirconia. After sintering to full density, no further time-consuming hard machining with diamond tools is needed. For individual esthetical requirements, the framework is coated with a veneer porcelain. Compared to the commercially available In-Ceram Alumina and IPS Empress2 restorations, the mechanical strength of zirconia frameworks is twice as high, allowing the restorations to bear the high mastication forces in the molar region. In terms of reliability, zirconia bridges fabricated by the DCM process are also superior to In-Ceram Alumina and IPS Empress2. A clinical study of three-unit dental bridges in the molar region found no problems after the first year of observation.

[Clinical study of zirconium oxide bridges in the posterior segments fabricated with the DCM system]. / Klinische Studie von Zirkonoxidbrücken im Seitenzahngebiet hergestellt mit dem DCM-System.

Today's dental reconstructive therapeutic concepts require restoration of high esthetic quality and excellent biocompatibility. Full ceramic reconstructions accomplish these requirements but only for anterior teeth and premolars. For all-ceramic bridges the mechanical strength was insufficient to withstand the posterior chewing forces. Frequently the interdental connectors cracked, and the only way to prevent these fractures was to overconture the connectors to a size of approx. 16 mm2. The high-tech ceramic zirconia is a potential alternative for three-to five-unit full ceramic bridges in the functionally loaded posterior segments. Experimental zirconia bridges which were fabricated using the DCM system (Direct Ceramic Machining System at the ETH Zurich, were tested in vitro. The frameworks were digitally enlarged by 20% and were easily milled from a presintered yet porous zirconia blank. After the milling process, the framework was densely sintered and shrank to its original size. Due to these positive in-vitro results a clinical investigation was started. 22 veneered zirconia bridges were luted; 19 molars and 25 premolars were prepared. The connectors, max. 7 mm2, of all these bridges, have been functionally loaded by antagonists. After a mean observation time of 385 days (307 days to 488 days), all 22 bridges did not show any cracks in the framework or in the veneering porcelain. The patients commented particularly on the low heat conduction rate of zirconia. The only endodontic problem which occurred could not be directly connected to the type of bridge framework. The reliability of zirconia bridges in this investigation was connected to the DCM-Process. No statement about other zirconia-systems can be made on the results of this study.

Aerobic power and body size affects the exercise-induced stress hormone responses to varying water temperatures.

Eleven active male subjects were used to examine the effects of anthropometrics and aerobic power (VO2max) on the plasma cortisol (CO) and urine excretion of catecholamines (NE and E) and dopamine (D) during exercise in differing water temperatures. Each performed 30 min of cycle ergometer exercise at 60% VO2max while immersed to the neck in 20, 25, 30, and 35 degrees C water (Tw). The change in core temperature (delta Tre) during exercise was related to Tw (p < 0.007). Plasma CO (exercise - rest) increased during the 20 degrees C trials and decreased during the 30 and 35 degrees C trials (p = 0.011). Catecholamines were generally higher during the 20 and 35 degrees C trials than the 25 and 30 degrees C trials, with significance for only D and NE during the 35 degrees C vs. 25 degrees C trials (p < 0.05). Multiple regression analyses (MRA) with CO during the 20 degrees C trials revealed that VO2max and delta Tre were significant partial correlates (p < 0.05), while in 35 degrees C water body mass index and delta Tre were significant partial correlates (p < 0.05). MRAs with NE and E during the 20 degrees C trials indicated that body fat was the only consistent significant partial correlate. The MRA for NE and E during the 35 degrees C trials were not significant; however, the MRA for D was significant. These results indicate that in addition to the core temperature, anthropometrics, and aerobic power affect the exercise-induced stress hormone responses during exposures to cold and warm water.

Sero-epidemiological survey for alveolar echinococcosis (by Em2-ELISA) of blood donors in an endemic area of Switzerland.

Sera from 17,166 blood donors living in 10 cantons of northern Switzerland in an area endemic for Echinococcus multilocularis were investigated by serological survey for alveolar echinococcosis (AE). A highly species-specific antigen (Em2) and a commonly used E. granulosus hydatid fluid antigen (EgHF) were compared for their suitability in seroepidemiology. EgHF showed a degree of nonspecificity which did not allow direct detection of AE cases. Antibody reaction with Em2 resulted in the detection of 2 asymptomatic clinical cases of AE (seroprevalence 0.01%) within this population of blood donors. A further 4 persons were positive in Em2-ELISA. These 4 persons had negative imaging studies and will be followed serologically and clinically.

[Prognostic factors of survival and tumor recurrence following surgery and radiotherapy for breast cancer with positive axillary nodes. La Chaux-de-Fonds, 1968-1975]. / Facteurs pronostiques de survie et de récidive tumorale après chirurgie et radiothérapie pour cancer du sein avec ganglions axillaires positifs. La Chaux-de-Fonds 1968-1975.

Survival and treatment failure are analyzed in a homogeneous group of 70 pre- or post-menopausal patients with operable breast cancer and histologically involved axillary nodes. From March 1968 to December 1975, all patients underwent simple or radical mastectomy, followed by radiotherapy in 67. The period of observation varied from 11 months to 10 years. Treatment failures were observed on 34 patients: 10 loco-regional relapses, 21 distant metastatizations, and 3 tumors in the other breast. Analysis of actuarial survival curves shows a statistically significant difference between patients with 1 to 3 positive axillary nodes and patients with 4 or more, but no difference with regard to the volume of the tumor and the patient's age. Comparison of disease-free period curves shows statistically significant differences between patients aged below and over 55 years, tumor of less or more than 2 cm, and 4 or fewer axillary nodes. These results are comparable to those in the literature and form a contribution to a Swiss study of post-operative adjuvant chemotherapy in breast cancer with positive axillary nodes.

[Integrating the blood transfusion service into hospital activities]. / Le service de transfusion sanguine intégrè á l'activité hospitaliére

The traditional and present activities of a regional transfusion center catering for the blood product requirements of a population of some 250 000 are reviewed. It is suggested that the work of a blood bank should be extended to the laboratory sector and cover immunohematology, hematology and coagulation. Through the laboratory the transfusion center would thus be in close liaison with hospital clinical departments. It is of advantage for the staff of the enlarged blood bank to perform some degree of clinical activity, to facilitate discussion of clinical and technical problems relating to hematological disorders in general.