The mutagenic activity of methylglyoxal (MG) was assayed in vitro in human lymphocytes [induction of chromosomal aberrations (CAs), sister chromatid exchanges (SCEs) and micronuclei] both in the presence and in the absence of metabolic activation (S9 mix). The Ames/microsome test was performed with the Salmonella typhimurium strains considered more responsive (TA102 and TA104). Positive results were obtained for all the genetic endpoints analysed. In human lymphocytes the activity of MG is decreased by the presence of S9 mix. In the in vivo studies, the metaphase analysis in the ileum and duodenum cells of mice treated per os with MG (400 and 600 mg/kg body wt) gave negative results for CA induction, while only a weak increase of SCE in duodenum cells at the higher dose was obtained. Dimethylhydrazine (25 mg/kg body wt), as positive control, was clearly active in inducing both CAs and SCEs in the same intestinal tissues.
The aim of the present study was to evaluate how hydroabrasion performs during composite removal. A standardized amount of composite was bonded to 40 enamel surfaces of extracted third molars, then removed with either a tungsten carbide bur mounted on a micro-motor handpiece without irrigation, a tungsten carbide bur mounted on a micro-motor handpiece with irrigation, a tungsten carbide bur mounted on an air-rotor handpiece, or hydroabrasion. The four treatment methods were compared using the enamelsurface-index and the adhesive-remnant-index and performing a Kruskal-Wallis statistical test to detect differences between each method' scores. Hydroabrasion produced significantly less damage to the enamel surface compared to the other three methods. Hydroabrasion was the cleaning method that produced less damages to the enamel surface, at a cost of a less efficient composite removal than tungsten carbide burs on micro-motor handpiece.
The identification of the hazard of chemicals to man has relied on the use of several animal models. However, the availability of various cell toxicity models as alternatives to the use of animals has stimulated attempts to evaluate in vitro data for use in the prediction of human toxicity. The cell toxicity models developed previously are capable of indicating a variety of endpoints susceptible to the activity of various chemical substances. The in vitro data derived so far from testing a variety of types of chemicals, have been used to develop toxicology profiles for twenty chemicals, which are presented in this paper. Data have been selected from among those already entered in the Galileo Data Bank, a computerised data system containing all the available existing data derived using in vitro methods.
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