Search

The aim of this study was to use the Zurich polyspecies biofilm model to compare the antimicrobial effects of chlorhexidine mouth rinses available on the Swiss market. As positive and negative controls, aqueous 0.15% CHX solution and water were used, respectively. In addition, Listerine® without CHX was tested. Biofilms in batch culture were grown in 24- well polystyrene tissue culture plates on hydroxyapatite discs in 70% mixed (1:1 diluted) unstimulated saliva and 30% complex culture medium. During the 64.5-hour culturing period, the biofilms were exposed to the test solutions for 1 minute twice a day on two subsequent days. Thereafter, the biofilms were dip-washed 3 times in physiological NaCl. Following the last exposure, the incubation of biofilms was continued for another 16 h. They were then harvested at 64.5 h. The dispersed biofilms were plated on 2 agar media. After incubation, colonies (CFU) were counted. All solutions containing CHX as well as Listerine ® significantly reduced the number of microorganisms in biofilms. According to their efficacy, the mouth rinses were classified into 2 groups. The two Curasept ADS solutions, Parodentosan, and the Listerine® mouth rinse reduced the number of total CFU by 3 log10 steps. This seems sufficient for a long-lasting prophylactic application. The two PlakOut® mouth rinses and the CHX control fell into the other group, where the number of CFU was reduced by 7 log10 steps. These mouth rinses are predestined for short-term therapeutic use. However, reversible side effects must be taken into account. It has thus far not been possible to formulate CHX products with effective ADS (Anti Discoloration System) additives without reducing antimicrobial activity.

Sterilization of metal instruments in Chemiclaves is undoubtedly the most protective mode of sterilization, because corrosion and formation of spots is minimal. In the past sterilization with Chemiclaves was criticised, because of the emission of formaldehyde by older models and the questionable efficacy of formaldehyde sterilization for wrapped instruments. In the present investigation the capability of the newest Chemiclaves (7000/8000) to sterilize dental instruments was investigated. To monitor sterilization efficacy filter paper strips loaded with spores of Bacillus stearothermophilus or dental instruments directly contaminated with these spores were used as biological indicators. The performance of the Chemiclaves was assessed with and without a full load of instruments; after running half of the program cycle, the spore strips in the chamber being either unpacked or packed into paper bags. In addition it was investigated, whether it was feasible to use a formaldehyde free sterilization solution (Steri-Vap) with these sterilizers. The daily performance of the Chemiclaves in a dental practice and the emission of formaldehyde were tested in a room < 10 m3, in which both apparatus were operated at the same time. The Chemiclaves 7000/8000 sterilized reliably under the set test condition, however, the formaldehyde-free sterilization solution did not lead to an acceptable efficacy of sterilization. The new Chemiclaves efficiently adsorbed formaldehyde vapours. Harvey sterilizers require a meticulous observation of the producer's instruction, because in comparison to saturated steam the chemical vapours have a lower heat capacity. The Chemiclaves 7000/8000 are recommended for the sterilization of well cleaned, dry instruments wrapped in original MDT paper bags.

Occasional clinical observations have shown extensive caries lesions in small children between 12 and 36 months of age, in some of which cases, while sugar intake history was negative, continuous use of teething jellies, lozenges or syrups was established. This prompted the hypothesis that such products were the source of the hidden fermentable sugars, and the sugar content of a number of products available on the Swiss market was therefore analyzed. Sucrose was determined enzymatically using the Boehringer sucrose/glucose UV-test. The content of other fermentable carbohydrates was checked by GLC. The use of such products should not be recommended for real or assumed pain related to the eruption of primary teeth. Among the eight products tested only one was found to be free of fermentable sugars. All other preparations contained 31-93% fermentable sugars, chiefly sucrose. Declaration of fermentable sugars in such products should be enforced by food and drug legislation.

In caries tests on rats, mutanase (mu-1,3-glucanglucano-hydrolase) was admixed in different quantities to a cariogenic diet. The animals were fed eight times a day with a feeding machine for 25 days. A highly significant inhibition of fissural caries was achieved by concentrations of over 50 MU per gram of diet. As a simultaneous plaque reduction was not observed, the effect of the enzyme appears to be due to reduced adhesion or colonization capacity of streptococcus mutans strains in the fissures.

The colonization on rat molars of S. sobrinus OMZ 176, S. mutans OMZ 376, or a combination S. sanguis OMZ 9 and S. sobrinus OMZ 176 after a short exposition to various fluoride solutions and disinfectants was tested in vitro. The test solutions included Act, Candida, Veadent, sodium fluoride, amine fluoride, stannous fluoride, zinc fluoride hexetidine, stannous fluoride/amine fluoride solutions, chlorhexidine and water. The sterilized rat molars were immersed in the above test solutions for 60 seconds, then incubated with streptococci in broth for 8 hours, again dipped into the same test solutions for 60 seconds and reincubated for an additional 30 hours. The streptococcal suspension contained 14C labelled sucrose solutions. The deposits on the molars were dissolved in 6N potassium hydroxide during 16 hours. Finally, the beta rays emitted by the dissolved radiolabelled suspension were counted using a scintillation counter. The sodium fluoride containing solutions exerted no or a very limited effect on the bacterial deposits. In contrast to the other test solutions, sanguinaria extract (Veadent mouth rinse) mildly inhibited the S. sobrinus and S. mutans deposits, but plaque formation by the combination of streptococci was not hampered. Zinc fluoride/hexetidine, amine fluoride and stannous fluoride/amine fluoride solutions had a distinct and significant inhibitory effect on S. sobrinus and S. mutans deposits, but only a weak effect when mixed cultures were used for plaque formation. Chlorhexidine significantly inhibited the deposits of the three bacterial strains used in these experiments.