The acid pattern in human dental plaque.

Lactic and volatile acids in standardized plaque samples from 11 subjects have been estimated by means of HPLC before and after exposure to sucrose in vivo. Total acid differed considerably between subjects, but the ratio of acids estimated within the plaque from different persons did not vary significantly. The time-dependent acid pattern following sucrose rinsing allowed the plaque samples to be divided into two groups: one showing only small changes in total acid production; and the other exhibiting a distinct increase in total acid up to 15 min after sucrose rinsing.

[The wall of the root canal after treatment with various instruments]. / Die Wurzelkanalwand nach Bearbeitung mit verschiedenen Instrumenten.

Root canal walls of freshly extracted teeth were examined with a scanning electron microscope before and after routine instrumental treatment of the root canal. The results indicated that the root canal wall must be freed of soft-tissue remnants and smoothed, and the orifices of the dental tubules blocked via meticulous use of broaches and files if the material used for a root canal filling is to be properly sealed.

[The surface structure of dentin after routine treatments]. / Die Oberflächenstruktur des Dentins nach praxisüblicher Bearbeitung.

A scanning electron microscopic study was made of the dentinal surface following preparation with various devices used routinely in the dental practice. The dentine prepared with diamond points showed deep fissured tracks from the individual diamond crystals, even when only slightly magnified. Compared with the untreated dentinal fracture surface, the orifices of the dentine tubules were crushed and obstructed. The surface is smoothed via finishing; the orifices of the dental tubules are no longer present. The picture remained unchanged after washing with H2O2 and cauterization with Ca(OH)2.

[Comparison of the metabolism of isolated streptococci and dental plaque]. / Der Stoffwechsel isolierter Streptokokken und Plaque im Verleich.

1. Isolated cultures of Streptococcus mutans form lactic acid as well as small amounts of formic acid and acetic acid during the anaerobic break down of glucose. The composition of the acids in terms of percent is independent of time. 2. Plaque specimens incubated in vitro show a complicated spectrum of substances; propionic and butyric acids are found in addition to lactic, formic, and acetic acids. The composition in terms of percent depends on the incubation period. The percentage of lactic acid drops as the incubation period is extended. 3. Just as the plaque, the product spectrum of isolated streptococci in terms of quantitative composition depends on the buffer capacity.

[Intra and extracellular acid spectrum of plaque incubated in vitro]. / Intra- und extrazelluläres Säurespektrum von in vitro inkubierter Plaque.

1. The different in the substance spectrum of incubated plaque produced by the change from glucose to sucrose is insignificant. 2. A variation in the buffer capacity, such as is typical for cariogenic plaque in vivo, markedly influences the proportional composition of the acids formed. 3. The product spectrum of a mixed bacteria population such as in plaque is time dependent. The reason for this dependence is probably the interaction of the individual types of bacteria with each other. 4. The spectrum of acid composition extracted from the plaque is different from that in the vicinity of the plaque.

[Reciprocal in vitro actions of Streptococcus mutans, Actinomyces and Veillonella: a simplified model for carbohydrate metabolism in plaque]. / Wechselwirkungen von Streptococcus mutans, Actinomyces und Veillonella in vitrao - ein vereinfachtes Modell für den Kohlenhydratmetabolismus in der Plaque.

Different acids can be found in vitro, if glucose is metabolized in plaque or by different combinations or oral bacteria: 1. Streptococcus mutans and Actinomyces do not show interactions concerning metabolism and formed acids. 2. Streptococcus mutans and Veillonella after short incubation time produce lactate; after long time of incubation acetic and propionic acid are main products and lactic acid diminishes. 3. Actinomyces and Veillonella react similar to Streptococcus mutans and Veillonella. Succinate produced by Actinomyces is fully utilized by Veillonella.

Lactate influx and efflux in the 'Streptococcus mutants group' and Streptococcus sanguis.

Lactate influx was measured in Streptococcus sanguis and in several strains of Streptococcus mutans by comparing the intra- and extracellular distribution of (14C)-lactate. Lactate efflux was followed enzymatically against rising external lactate concentration. The glucose concentration was monitored in the same way. With S. sanguis OMZ 9, lactate was transported into the cells when a high external lactate concentration and a pH gradient were established. The transport rate was approximately 1,000 nmol lactate per minute and milligram protein. No lactate influx could be measured with four strains of the 'S. mutans group' (OMZ 51, 634, T3/13 and NCTC 10449). Metabolizing cells of S. mutans NCTC 10449 were able to transport lactate even against an external lactate concentration of 92 mmol/l at pH = 7. The transport rates ranged from 1,200 to 750 nmol lactate/min mg protein decreasing with increasing external lactate concentration. While an external pH = 9 had little influence on transport, transport rates decreased to 440 nmol/min mg protein at pH = 5.

[Mercury concentrations in blood and urine in persons with and without amalgam fillings]. / Uber die Quecksilberkonzentrationen in Blut und Urin von Personen mit und ohne Amalgamfüllungen.

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.

[Mercury concentrations in blood and urine before and after placement of non-gamma 2 amalgam fillings]. / Quecksilberkonzentration in Blut und Urin vor und nach dem Legen von Non-gamma 2-Amalgamfüllungen.

The object of the study was to determine whether mercury concentrations in blood and urine were increased directly after placement of non-gamma 2-amalgam fillings. Our cohort consisted of 45 subjects, male and female, age between 19 and 45 years, who had amalgam fillings and were not exposed to mercury on their jobs. Thirty subjects received non-gamma 2-amalgam fillings, 15 did get new fillings. Cold, flameless atom absorption spectrometry was used to analyze mercury levels in blood and urine samples before and for 24 hours after placement of the amalgam fillings at one hour intervals. Mercury concentrations in blood (before and after) and - before placement of new non-gamma 2-amalgam fillings - in urin were below the normal upper limit in all 45 subjects. Mercury concentrations in urin after placement of new fillings did not show any increase over 24 hours. Median values varied between 1.0 and 2.1 micrograms Hg/g creatinine and thus were also within the normal range.