Biomedical subjects
Publications and source records attributed to P Lockowandt.
Information concerning initial pellicle forming (dental cuticle) are possible via contact-angle determination. Not only the type of the restorative material but also its surface processing (structure) influence the initial forming of the pellicle. The higher the surface energy of a material, the more complete and quicker the masking of the surface by the initial pellicle.
Selected material properties of hot and cold polymerized denture basic materials (polymethylmethacrylate) were investigated after different methods of isolation: alginate, tin foil and silicone. Both tin foil and silicone isolation the handling of which is much easier result in a decreased portion of porosities and an increased microhardness in the PMMA.
In the present paper hot and cold polymerized denture basic materials were investigated after isolation by means of alginate, tin foil and silicone. Measurements of roughness and internal stresses after polymerization show that the advantages of a silicone isolation correspond to those of a tin foil isolation, where the clinically important smoothing effect of a silicone isolation is convincing using simple laboratory handling.
The beneficial effect of fluoride-containing amalgam in preventing recurrent dental caries depends on the ability of the material to deliver fluoride (F). A two-chamber diffusion cell has been employed to monitor the diffusion of F in freshly prepared amalgam sections (membranes) as well as in amalgam sections stored in F solution for 15 d. The diffusion of 125I was also monitored, as a reference. Five and ten successive measurements at 72 h intervals were made on the fresh and stored amalgam specimens, respectively. The average diffusion coefficient, D, of F and 125I in fresh amalgam was 2.39 x 10(-10) and 1.85 x 10(-10) cm2/s, respectively. For stored amalgam, the average D of F during a 30 d experiment was 1.35 x 10(-10) cm2/s. The average D of F in stored amalgam, during the first 15 d of the experiment, was 31% less than in fresh amalgam (p less than 0.01). A decline in the diffusion process was observed during the course of the experiments. During 15 d diffusion in fresh amalgam and 30 d diffusion in stored amalgam the cumulative diffused F were 0.79 and 0.88% of the F in the source. SEM findings revealed the deposition of corrosion products on amalgam stored for 3 months in 0.19% F solution.
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The temperature and the chemical character of an acetylene-oxygen flame change with change in the gasmixture. When heating a Co-Cr alloy with this flame both temperature and chemical character in the parts of the flame used may influence the temperature increase of the alloy. To study the influence of different acetylene-oxygen flames on the heating process of dental Co-Cr alloy, a gasmeasuring and casting equipment was constructed. This made it possible to cast in a standardized way.
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