[Investigations on suckling piglets castrated under automated isoflurane anesthesia]. / Untersuchungen zur automatisierten Isoflurannarkose bei der Saugferkelkastration.

OBJECTIVE: Investigation of defensive reactions, piglet losses, post-bleeding and recovery time of suckling piglets castrated under automated isoflurane anesthesia as well as measurements of isoflurane concentrations in ambient air and estimation of the cleaning and disinfection success of anesthesia masks. MATERIAL AND METHODS: A total of 955 suckling piglets (age: 4.0 ± 1.2 days; weight: 2.0 ± 0.5 kg) were castrated under automated isoflurane anesthesia (PorcAnest 3000®) after the administration of a non-steroidal anti-inflammatory drug. Reactions during the procedure were assessed before castration using the interdigital claw reflex and during castration by defensive movements and vocal response. The piglets' recovery time was evaluated in the stable corridor (pass 1) and the farrowing pen (passes 4-5). In 73 animals, the spermatic cord was cut with a scalpel and the post-operative bleeding visually evaluated. In addition, exposure measurements of isoflurane were performed and anesthetic masks were examined for total bacterial contamination and indicator bacteria before and after the anesthetic procedure and following their disinfection. RESULTS: Following insufflation of isoflurane for 90 seconds 94.3 % of the piglets and after prior testing of the interdigital claw reflex and possible extension of the anesthetic supply 95.3 % of the piglets showed no or minimal defensive movements during castration. An anesthetic incident occurred in 0.9 % of the piglets, but no animal died. The recovery time lasted 7.3 ± 4.7 minutes (pass 1) and 6.2 ± 3.3 minutes (passes 4-5). Cutting the spermatic cord with a scalpel led to a higher post-bleeding score (p < 0.001) compared to use of the emasculator. Isoflurane concentrations in ambient air ranged between 4.5 und 28.1 mg/m3. Masks disinfection reduced the total germ count by 99.8 %. Contaminations with Escherichia coli and MRSA were no longer detectable in 4 of 6 cases after disinfection. CONCLUSION: Isoflurane anesthesia led in over 94 % of the piglets to no or minimal defensive reactions during castration. Anesthetic incidents occurred rarely and no piglet losses were recorded. Therefore, automated isoflurane anesthesia is associated with a low risk for suckling piglets. Measurements of isoflurane concentrations on persons involved were below the internationally lowest limit value. Disinfection of the anesthesia masks may prevent germ transmission between animal groups via this potential vector.

Influence of various types of damage on the fracture strength of ceramic femoral heads.

Ceramic-on-ceramic articulations are a frequently used bearing for total hip replacements. This success mainly is due to their excellent tribological properties. Ceramics can withstand high pressure loads due to its brittleness but only low bending stresses. A ceramic ball head fracture is the result of subcritical crack growth. This kind of fracture in vivo can abet by damage or contamination of the stem cone. The main goal of this work is to provide a risk assessment of different possible damage mechanisms and contaminations that may result in lower fracture strength of a ceramic ball head. To simulate potential causes, different types and dimensions of metal wire, foils, hair, and lubricants were inserted between the ceramic ball head and the metal cone of the stem. The test results clearly show that fracture strength is negatively influenced by most of the inhomogeneities between the cone and the head because they increase the peak stresses acting on a part of the ceramic ball head. The results of this article clearly confirm the demand for an undamaged taper fit "free of contamination" between the ceramic head and the metal cone during implantation.

Preservation of microelastic properties of dentin and tooth enamel in vitro--a scanning acoustic microscopy study.

OBJECTIVES: The aim of this study was to examine the influence of storage media on the elastic properties of dentin and tooth enamel with respect to the storage period. Several reports suggest that saline and other aqueous solutions may induce chemical reactions and the dissolution of minerals, which in turn may cause alterations of elastic tissue properties. METHODS: Three non-erupted human wisdom teeth were extracted and divided in three slices. Sections were stored in three different media for a maximum period of 21 days. During this time all sections were inspected by time-resolved 50-MHz scanning acoustic microscopy. RESULTS: Storage in saline solution resulted in a progressive decrease of the acoustic impedance up to 70% in dentin but not in enamel tissue. Hank's balanced salts solution and artificial saliva appeared to maintain the elastic properties of dentin and enamel during the entire time of storage. The measurements of surface wave velocities did not show significant differences. High resolution (900 MHz) inspection of sections cut perpendicular to the surface exposed to the storage media for 21 days revealed a progressive increase of impedance in dentin up to the initial values at a depth of approximately 300 microm. SIGNIFICANCE: These findings suggest that quantitative SAM is a suitable tool for assessing surface and sub-superficial elastic properties of tooth tissue.