Audun Attramadal

Effect of nystatin and chlorhexidine digluconate on Candida albicans

Polyene antibiotics such as nystatin and amphotericin B are among the most widely recommended drugs for use against oral candidiasis. It is also generally accepted that chlorhexidine gluconate is an appropriate adjunct or an alternative to specific antimycotic drugs. The aim of the present study was to examine the effect of the combination of nystatin and chlorhexidine digluconate on Candida albicans in vitro. The minimum inhibitory concentration (MIC) value for the combination of the two drugs was found to be significantly higher than the values for each of the drugs alone, approximately 33 times the MIC value for the nystatin solution and 4 times the value for chlorhexidine digluconate. The results of the MIC study and the presence of a precipitate in all combinations of nystatin and chlorhexidine digluconate showed that the combination of the drugs is not effective in vitro against Candida albicans. The most likely reason is that a low solubility chlorhexidine-nystatin salt is formed, thus rendering the combined drug complex ineffective as an antibiotic agent.

The effect of stannous fluoride on human plaque acidogenicity in situ (Stephan curve)

A system employing an Ingold glass electrode was shown to give reliable measurements of pH drops in dental plaque in situ (Stephan curve readings). The system was used to demonstrate that mouthrinses of 0.2 per cent aqueous solutions of stannous fluoride reduced the pH drops markedly for at least seven hours. A reduction of the stannous fluoride concentration increased the pH drops and decreased the duration of the inhibiting effect. A commercial toothpaste containing stannous fluoride and stannous pyrophosphate had an effect similar to the 0.2 per cent mouthrinse. It was shown that tin accumulated in dental plaque after application of solutions containing stannous fluoride. About 40 per cent of the amount of tin present in the plaque immediately after the mouthrinse was still retained seven hours later. It is suggested that the reduction in acid formation may be caused by stannous ions adsorbing to the bacterial cell wall thus disturbing membrane transport mechanisms, or through inhibition of enzyme systems essential in the fermentation of sugars. The observed effect may be a part of the mechanism involved in the caries preventive function of stannous fluoride.

The content of lead, cadmium, zinc and copper in deciduous and permanent human teeth

The aim of the study was to compare the uptake of the trace metals lead, cadmium, zinc and copper, in deciduous and permanent teeth. The material consisted of teeth extracted in the Oslo area. The teeth were digested in hydrochloric acid, and analyses were made by differential pulse stripping voltammetry. Similar levels of cadmium and zinc were found in deciduous and permanent teeth. The copper content varied little in deciduous teeth, but in permanent teeth a wide variation in the copper levels was found. The content of lead in deciduous teeth was found to be higher than in permanent teeth.

Iron discoloration of acrylic resin exposed to chlorhexidine or tannic acid: a model study.

A clinical model was introduced to study the ability of chlorhexidine, tannic acid, and iron to discolor dental plaque formed on acrylic resin surfaces. None of the agents caused discoloration when applied individually five times daily during a 5-day period. However, exposure of the dental plaque to either chlorhexidine or tannic acid before the iron applications produced marked staining. Possible mechanisms, among which denaturation appears to be significant, are discussed. The use of a strong oxidizing agent, peroxymonosulfate, completely bleached the established discolorations.

Uptake and retention of tin by S. mutans

The uptake of tin by S. mutans from stannous fluoride or stannous chloride solutions was determined by atomic absorption spectroscopy. The uptake occurred rapidly, and the microorganism was shown to have a greater capacity and higher affinity to uptake of tin than of other metal ions tested. In 10 mM solutions, bound tin amounted to 17.5 per cent of the cellular dry mass. The tin uptake was independent of cell metabolism. The cell bound tin could not be washed out with water or saline, but 84 per cent was removed by ethylenediaminetetraacetic acid solutions. When pH was lowered by low 2, increasing loss of bound tin occurred. It is suggested that the binding occurs to polyanionic structural polymers in the cell wall and the cell capsule.

Heavy trace elements in ancient Norwegian teeth

The present work was undertaken in order to determine the content of lead, cadmium, copper and zinc in 26 teeth retrieved from burial-grounds in various parts of Norway, dated from A.D. 200 up to 1850. The analyses were made by differential pulse stripping voltammetry on hydrochloric acid digests of the teeth. High levels of lead were found in teeth dated from ca A.D. 1500 from Gimsøy Kloster and Tønsberg. Teeth originating from A.D. 200 showed a high content of Cd, Cu and Zn.