Carbohydrate metabolism of Streptococcus mutans in dental plaque in gnotobiotic rats.

The fermentation products of Streptococcus mutans C67-1 were investigated in fissure plaque of rats, that were mono-associated with this strain. In addition to lactic acid, acetic acid and ethanol were present. The finding that a mixed acid fermentation occurred and that ethanol was produced suggests that the carbohydrate source rather than the nitrogen source was the growth-limiting substrate for Strep. mutans in plaque.     

Clinical study of an amine fluoride gel and acidulated phosphate fluoride gel

Abstract This study compared caries inhibition in children by an amine fluoride and an acidulated phosphate fluoride when administered in a topically applied gel. In addition, the effects of applying amine fluoride daily and weekly were compared. Four hundred and sixty-eight children, ages 6 to 13, were randomly assigned to one of five treatment groups and received a total of five, 5-minute treatments. The treatment and interval between each of the five treatments were as follows: (A) acidulated phosphate fluoride daily, (B) amine fluoride daily, (C) amine fluoride weekly, (D) placebo daily, and (E) placebo weekly. When the children were examined for total Decayed, Missing, and Filled Surfaces (DMFS) increments 2 years later, no significant differences were observed. However, when the data were examined for effects on DMFS for a specific tooth surface, significant restriction (61 %) of occlusal increment was shown in the group which was treated with amine fluoride daily for 5 consecutive days as compared with the control group.     

Two-way cross-reactions between serotypes of Actinomyces viscosus.

Three antigen preparations were obtained from cultures of A. viscosus Serotypes 1 and 2. Ammonium sulphate (60 per cent w/v) and acetone precipitates were obtained from cellfree culture supernatants of late-log phase cultures of each organism. The third preparation consisted of the supernatant obtained after homogenization of late-log phase cells of each organism. Immunodiffusion and immunoelectrophoresis using rabbit antisera to each serotype were used to identify the soluble antigens present in each preparation. Ammonium sulphate preparations proved to be the most reproducible and contained the greatest number of identifiable antigens. Homologous and cross-reacting antigens were identified and two-way cross-reactions were observed between the serotypes.     

Induction of cellular hypersensitivity to oral microorganisms in guinea-pigs

The ability of oral microorganisms (Actinomyces viscosus, Bacteroides melaninogenicus, Veillonella alcalescens and Streptococcus mutans) to elicit cellular hypersensitivity in guinea-pigs was investigated by the macrophage migration inhibition test. All animals sensitized with these microorganisms, emulsified in oil adjuvant, yielded peritoneal cells which were significantly inhibited in migration by the homologous bacterial antigen. These microorganisms showed no cross-reactions and there was little quantitative difference in their ability to elicit cellular hypersensitivity.     

Matches,clips, needles,or pins

Several methods for positioning dowel pins used in the fabrication of removable dies have been presented. Needles, pins, paper clips, hairpins, and matches are all useful in positioning dowel pins in the impression. The use of paper matches is a simple and effective method for holding the dowel pin in the proper relation while the die stone portion of the cast is being poured.