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In an interdisciplinary study starting 2.5 years ago patients with various symptoms, which they associate with amalgam fillings, were examined. According to the first results of this study with 50 patients, the Hg-concentration in urine does correlate with the amount of amalgam fillings before and after taking DMPS (2,3-Dimercapto-1-propane-sulfonic-acid), but with a maximum of 66.4 micrograms Hg (24 h urine) the amounts of mobilization measured were significantly below toxicologically critical limits. Only in 3 patients did the individual immunological values (CD4/8 ratio, antinuclear antibodies) by far exceed standard values. In one case an allergy to amalgam is suspected. 40% of the patients showed a pathological psychiatric status (neurosis, depression, etc.). Another quarter had psychological problems like alcoholism or drug abuse. There is no reason at the moment to reject amalgam as filling material either because of the measured Hg-concentrations or because of any immunological or allergological findings.

Irrigation of the root canal is carried out to remove the smear layer and the overlying pulp tissue remnants and dentin chips left by preparation. Our results show that even high volume irrigation is less effective in the apical section than towards cervical. A positive effect of activated continuous irrigation was demonstrated above all in the apical third of the root canal. Almost complete removal of both the smear layer and the overlying debris was achieved. Since high volume, continuous activated irrigation is superior to any other form of irrigation, particularly in the apical section, the results of our studies suggest that further efforts to develop such a root canal irrigation system to the state in which it can be clinically used are necessary.

The present SEH study could show that radiogenic caries is accompanied by morphological changes at the dentine-enamel junction. These changes appear as lacunar defects of up to 300 microns in size. This kind of defect was found in 28 of 32 teeth which were exposed to radiation of more than 40 Gy. In a control group with caries of the smooth surfaces no comparable results could be obtained.

The dryness of root canals was checked using special paper points prepared with an indicator medium. In the presence of moisture these paper points promptly change from white to blue in color. In a two-step in vitro experiment, moisture was always demonstrated at the apical stop and in the apical third of the canal wall, although according to clinical criteria we believed the root canal to be dry. The results were not influenced by any previous manipulations of the prepared root canals. It may be recommended for routine root canal therapy to observe the following rules: 1. use alcohol for the last irrigation, 2. keep using larger paper points in between, 3. use 2 to 3 paper points more after you believe the root canal is dry, 4. remove the last paper point right before obturating the root canal.

Since Cerment-cement has been recommended also for Black's Class II cavities in posterior teeth, it was the goal of this study to compare its marginal adaptation with that of amalgam after alternating thermal loads. Black's Class II cavities were prepared in extracted premolar teeth and filled with amalgam or Cermet. Three different application techniques were used for the Cermet fillings: 1. syringe only, 2. syringe and amalgam plugger, 3. individual occlusal plugger. Before and after alternating thermal loads the proximal margins were studied by SEM using replicas. The poorest results were found in the Cermet fillings applied with the syringe only. In the other three groups the results were comparable. These findings suggest that cermet cement should not be applied with exclusive use of the syringe, but should always be additionally adapted with a plugger.

After removal of the smear layer all root filling materials tested were able to infiltrate dentin tubules. With the cement types studied, filled dentin tubules were found even at a distance of 100 microns from the root canal. The infiltration of the dentin tubules now explains the outstanding results of pigment penetration tests. The question, if the smear layer is to be removed or not, can now be answered "yes".

Using flameless atom-absorption spectroscopy, the mercury concentration in the urine and in the blood of 102 persons was determined in a double-blind experiment. The subjects were divided into four groups: persons with and without amalgam fillings as well as persons with and without occupational contact with mercury and amalgam. Mercury concentrations in the blood and the urine were the same in relation to the presence or absence of amalgam fillings. The individual values varied, depending on the nutrition, and did not correlate with the number of amalgam fillings present in the individual case. Persons with occupational contact with mercury and amalgam excreted slightly more mercury in the urine. Even these values however were far below the upper limits of the range of normalcy.

106 Ketac-Silver fillings in deciduous molars were reevaluated after 1 to 3.3 years, i.e. 25 month on the average. About 90% of 50 occlusal fillings and about 84% of 56 multisurface restorations were unchanged. Without claiming statistical evidence for their conclusiveness, we consider these results as an indication that cermet cements are a useful alternative to amalgam fillings in deciduous teeth, particularly since the life of these fillings is limited to the time until the milk tooth is physiologically lost.

By means of the occlusal recording instrument (ORI), jaw models can be measured three-dimensionally and filed with respect to axes and skull. In clinical trials evaluated with the ORI, it was shown that the position of the maxilla in the skull can be transferred to the articulator with great accuracy. Suggestions are given for improvements to refine the method of measurement. If the third point of reference is also tattooed, the accuracy of the transference of the face-bow is considerably increased. Under these conditions the apparatus is suitable for checking the accuracy of the transference of the face-bow and for photographic documentation.