James Nuckolls

Descriptions of actinomycetes and other pleomorphic organisms recovered from pigmented carious lesions of the dentine of human teeth

Abstract Eighty-six strains isolated from pigmented carious lesions of human teeth were divided into six groups based upon final pH levels in glucose broth and fermentation of lactose. Within each type, except for two miscellaneous groups, strains showed little variation in results of bacteriologic examinations. Cytologic methods for cell walls and chromatinic bodies in combination with warm-stage observation were very helpful in identifying these eighty-six pleomorphic strains. Of these, twenty-two Type IIIB strains were identified with Nocardia , nineteen Type IIIA strains with Actinomyces , seventeen Type II strains with Corynebacterium , and six Type IV strains with Bacillus . There was no category to apply to ten streptococcal-diphtheroid strains of Type I, suspected to be a new genus. Six strains of Type IIIC appeared to be oral actinomycetes (probably Nocardia ) but were not a homogeneous group. The six remaining strains appeared to be Eubacteriales but they were quite variable in morphology and in biochemistry.

Actinomycetes and other pleomorphic organisms recovered from pigmented carious lesions of human teeth

Abstract In order to establish the flora of caries lesions of dentine it is essential to take measures which rule out contamination by microorganisms from tooth surfaces of specimens taken for cultivation. A survey of the literature indicates that antiseptics may be ineffective in establishing surface sterility. Our results indicate that sterility of surfaces may be achieved by heating teeth in paraffin at 200° C. for suitable periods and that under these conditions organisms in the interior of the tooth are not necessarily killed. Since in this investigation we are primarily concerned with bacteria found at the innermost part of the preclinical and clinical lesions, destruction of desired organisms by the methods employed to kill undesirable ones on the outer surfaces does not seem to be important. So that contamination of our samples from more superficial carious material might not occur, specimen teeth were split through carious lesions with sterile nippers. Samples were then ground from the split tooth surfaces with sterile burrs. Samples so collected were used to inoculate plates of culture media. All of these operations were carried out under aseptic conditions. In specimens from representative preclinical and early clinical caries pleomorphic bacteria predominated. The form most frequently isolated appeared morphologically to be possible actinomycetes. Further studies of the characteristics of these microorganisms will be reported in a subsequent article.

Frequency of ninhydrin staining in the enamel surfaces of completely unerupted, undecalcified human third molars in relation to the problem of caries susceptibility

Abstract Under our experimental conditions it is believed that a positive ninhydrin stain on the surface of completely unerupted, undecalcified human third molars indicates the presence of lower molecular weight polypeptides and amino acids. The positive stains appeared to occur to a significant extent in potentially caries-susceptible regions of the tooth surfaces (such as the occlusal surfaces). The stains also occurred with a frequency similar to one of those with which caries might have been expected to occur in these teeth if exposed to the oral environment.

Organic tracts in the enamel of completely unerupted human third molars.

Abstract Unerupted human third molars have been studied to determine the gross distribution of protein in the enamel. It is emphasized that organic tracts of developmental origin can only be demonstrated in the enamel of unerupted teeth which have never been exposed to the oral environment because other organic tracts may be formed in cracks or by bacterial invasion. A modification of Ehrlichs reagent was used to indicate protein. Indications of proteins were found at the dentinoenamel junction, under pits and fissures, and, in some cases, penetrating from the smooth, vertical tooth surfaces to the dentinoenamel junction. It has been established that organic tracts of developmental origin may occur in unerupted third molars.