The Relationship of Extrinsic Dark Tooth Stains to Dental Caries

Reid, James S (1974) The Relationship of Extrinsic Dark Tooth Stains to Dental Caries. PhD thesis, University of Glasgow.

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The purpose of this investigation was to assess the relationship between certain coloured extrinsic tooth stains and dental disease with particular emphasis on black extrinsic tooth stain. Bacteriological and chemical analyses were carried out into the aetiology and composition of the black material found upon the teeth of certain individuals. An epidemiological survey was also carried out, in which dental caries, calculus, dental cleanliness and coloured extrinsic tooth stains were recorded on 928 children aged thirteen years. An analysis was made of the data to study possible relationships between dental caries and the other variables particularly black extrinsic tooth stain. It was found that: 1. Girls brushed their teeth more often than boys and had significantly cleaner mouths. 2. A significant correlation was found between oral hygiene and, gingivitis in both boys and girls. 3. A mean number of 8.25 D-M-F teeth per child was found. 4. Children with dark extrinsic tooth stain had a significantly lower dental caries experience than those with either no stain or stain of other colours. 3. No significant correlation was found between the standard of oral hygiene in children with no tooth stain and children with extrinsic black stain. 6. A significant correlation between the stated sweet consumption and numbers of D-M-F teeth was found. 7. No significant correlation between oral hygiene and the D-M-F rate was found. 8. A significantly lower oxygen tension was found in children with extrinsic black tooth stain than those with no stain. 9. Greater numbers of Bacteroides melaninogenicus were found in children with black extrinsic tooth stain than those with no stain but the correlation between the groups was not significant. 10. Iron and sulphide was found in gingival scrapings from children with black stain upon their teeth but a less vigorous reaction for sulphide only was found in gingival scrapings from children with no coloured tooth stains. 11. Spectral studies on the supernatant of an homogenate of gingival debris from the black stain group indicated that significant amounts of iron-sulphur proteins or haem compounds were not present. 12. Iron was found in the black material recovered from culture plates on which Bacteroides melaninogenicus was grown. However, the test for sulphide was negative. 13. Spectrographic analysis of the supernatant from the microbiological culture plate did not indicate that significant amounts of iron-sulphur proteins or haem compounds were present. 14. Examination of the ultrastructure of Bacteroides melaninogenicus from a pure growth demonstrated the presence of a cell wall, cytoplasmic membrane, "bridges" and a dense crust. Both the cell wall and the cytoplasmic membrane were seen as triple layered structures. 13. Cell division of Bacteroides melaninogenicus appeared to be by inward growth of the cell wall-cytoplasmic membrane complex until fission was complete. 160 Electron microscopic studies of the organisms on the tooth section demonstrate both a cell wall and cytoplasmic membrane. These organisms were also shown to be gram negative cocco-bacilli. 17. An homogeneous cell-free dark material was demonstrated interposed between the microbial layer and the tooth surface The results show that children with extrinsic black tooth stain had a lower D-M-F rate than children with no tooth stains. The numbers of Bacteroides melaninogenicus were greater in the black stain group although not sufficiently so to be statistically significant. Chemical analysis of gingival scrapings revealed the presence of iron and. sulphide in the black stain group but only thiocyanate in the gingival scrapings from the control group. Thus the black material from both in vivo and. in vitro sources has iron with sulphide present in the former. These factors plus the lower oxygen tension found in the mouths of the black stain group suggest that Bacteroides melaninogenicus is the aetiological agent responsible for the extrinsic black stain found on the teeth of certain children in this study. Certainly if black stain could be produced on the teeth of germ-free animals using Bacteroides melaninogenicus this would be further evidence to support the part played by these organisms in black stain production. This line of investigation would be interesting in spite of the fact that Bacteroides melaninogenicus would not become established as a monocontaminant in mice (Gibbons et al., 1964). The part played by the organisms in the dental caries process could then be studied and it is hoped that further work into both these topics will be undertaken. Perhaps the results of this study will strengthen the statement made by Bibby (1931): "The principal value of this discussion seems to be its suggestion that a sweeping condemnation of all deposits on the surface of the teeth is unjustified, as at least, this particular plaque appears to exert nothing but a protective action".

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Dentistry
Date of Award: 1974
Depositing User: Enlighten Team
Unique ID: glathesis:1974-78662
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 15:04
Last Modified: 30 Jan 2020 15:04

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