| 1. |
- Dahlén, Gunnar, 1944, et al.
(författare)
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A microbiological study in relation to the presence of caries and calculus.
- 2010
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Ingår i: Acta odontologica Scandinavica. - : Informa UK Limited. - 1502-3850 .- 0001-6357. ; 68:4, s. 199-206
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To examine whether oral microflora in individuals with caries differs from that of individuals with calculus in Thai adolescents with poor oral hygiene. MATERIAL AND METHODS: One hundred 13-year-old schoolchildren from Southern Thailand were examined for the presence of caries, calculus and plaque and saliva pH was also determined. Saliva samples were analysed by culture and approximal supragingival plaque samples were analysed with the DNA-DNA hybridization method ('checkerboard'). RESULTS: Among the 100 children, mean DMFS was 3.43 [standard deviation (SD) 2.82] and 90% had calculus. The correlation between DMFS and the calculus index was 0.064. A total of 36 children were caries-free and 56 had calculus including teeth other than those in the lower anterior region (calculus score > or =3). A total of 23 caries-free children with a high calculus score (> or =3) were compared with 22 children with the highest DMFS [mean 11.19 (SD 5.58)] and a calculus score < 3. No significant difference was obtained for saliva and plaque pH. The salivary levels of mutans Streptococci and Lactobacilli were low. Significantly more children in the caries group had high levels of glycolytic Prevotella nigrescens and Filifactor alocis in plaque compared with the calculus group. Calculus cases had a significantly higher total viable count in saliva. CONCLUSIONS: There was no inverse correlation between the presence of caries and calculus at a population level and a high calculus score only marginally reduced the individual likelihood of having caries. Several glycolytic bacteria were related to caries, while no specific bacteria could be related to calculus formation. Calculus seemed to be more closely related to poor oral hygiene.
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| 2. |
- Pahumunto, Nuntiya, et al.
(författare)
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Virulence of Aggregatibacter actinomycetemcomitans serotypes and DGGE subtypes isolated from chronic adult periodontitis in Thailand.
- 2015
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Ingår i: Anaerobe. - : Elsevier BV. - 1095-8274 .- 1075-9964. ; 36, s. 60-4
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Tidskriftsartikel (refereegranskat)abstract
- A high proportion of non-serotypeable isolates of Aggregatibacter actinomycetemcomitans among Thai periodontitis cases has been previously reported. The aim of this study was to investigate the expression of leukotoxin and toxicity, cytolethal distending toxin (Cdts), and internalization and the killing effect on fibroblasts by A.actinomycetemcomitans subtypes from Thai chronic periodontitis cases. A total of 96 A.actinomycetemcomitans strains from 37 periodontitis cases, previously serotyped with PCR and subtyped with DGGE, were examined for the presence of the ltx gene and cdt genes (cdtBC), and tested for leukotoxin expression, leukotoxicity, internalization, and apoptosis of fibroblast cells. The ltx gene was present in all isolates, while 84.4% showed the cdtBC gene. Two strains with a JP2-like ltx gene with a deletion of 530bp in the promoter region, serotyped as c, showed virulence of similar magnitude to the JP2 strain. Furthermore, a higher virulence was found in the two non-serotypeable DGGE subtypes, NS1 and NS2, compared with the serotypeable strains (serotype a-f, serotype b and d were absent). Generally, the virulence of strains obtained from deep periodontal pockets was higher than those isolated from shallow non-bleeding pockets. A.actinomycetemcomitans subtypes isolated from adult Thais with chronic periodontitis showed a highly variable virulence, leukotoxin expression, leukotoxicity, internalization and apoptosis of fibroblast, and are regulated both genetically and environmentally.
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| 3. |
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| 4. |
- Youravong, Nattaporn, et al.
(författare)
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Chemical composition of enamel and dentine in primary teeth
- 2007
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Ingår i: Science of the total environment. ; 389:2-3, s. 253-258
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Tidskriftsartikel (refereegranskat)abstract
- Enamel and dentine in teeth of children with high blood levels of lead were analyzed by means of secondary ion mass spectrometry (SIMS) and X-ray micro-analyses (XRMA) and compare with teeth from children with low blood levels of lead. The SIMS analysis revealed detectable levels of Pb in dentine close to the pulp. The XRMA analyses could not detect any lead. There were no differences found in lead level in enamel of high lead level exposed teeth from low level exposed. The results confirm that children with high blood levels of lead have an uptake of lead in dentine close to the pulp.
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| 5. |
- Youravong, Nattaporn, et al.
(författare)
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Chemical composition of enamel and dentine in primary teeth in children from Thailand exposed to lead.
- 2008
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Ingår i: The Science of the total environment. - : Elsevier BV. - 0048-9697. ; 389:2-3, s. 253-8
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Tidskriftsartikel (refereegranskat)abstract
- Enamel and dentine in teeth of children with high blood levels of lead were analyzed by means of secondary ion mass spectrometry (SIMS) and X-ray micro-analyses (XRMA) and compare with teeth from children with low blood levels of lead. The SIMS analysis revealed detectable levels of Pb in dentine close to the pulp. The XRMA analyses could not detect any lead. There were no differences found in lead level in enamel of high lead level exposed teeth from low level exposed. The results confirm that children with high blood levels of lead have an uptake of lead in dentine close to the pulp.
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| 6. |
- Youravong, Nattaporn, et al.
(författare)
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Lead associated caries development in children living in a lead contaminated area, Thailand.
- 2006
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Ingår i: The Science of the total environment. - : Elsevier BV. - 0048-9697. ; 361:1-3, s. 88-96
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Tidskriftsartikel (refereegranskat)abstract
- In an observational cross-sectional design, a sample of 292 children aged 6-11 years from two primary schools around a shipyard area, known to be an area contaminated with lead (from the industry), were examined to verify the cariogenicity of lead. The number of decayed and filled surfaces on deciduous teeth (dfs), and the number of decayed, missing, and filled surfaces on permanent teeth (DMFS), the salivary flow rate, pH, buffer capacity, oral hygiene, Lactobacillus spp. and mutans streptococci counts were recorded. The mean (range) of DMFS and dfs were respectively 1.3 (range 0-17) and 13.2 (range 0-45); and the geometric mean blood lead level (PbB) and SD were 7.2 and 1.5 microg/dl. The level of dfs, but not DMFS correlated with the blood lead level (R(s)=0.25, p=0.00 / R(s)=0.09, p=0.14). The odds ratio for DMFS>or=1 and dfs>5 for a doubling of PbB after adjusting for other factors were 1.28 (95%CI, 0.81-2.04; p value=0.35) and 2.39 (95%CI, 1.36-4.20; p value=0.004), respectively. The cariogenicity of lead is evident in deciduous teeth but not in permanent teeth for this age group.
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| 7. |
- Youravong, Nattaporn, et al.
(författare)
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Microbiology in toothbrush samples from children exposed to lead in southern Thailand.
- 2007
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Ingår i: Acta odontologica Scandinavica. - : Informa UK Limited. - 0001-6357 .- 1502-3850. ; 65:1, s. 22-8
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The purpose of this study was to evaluate the prevalence and level of selected oral bacterial species in association with dental caries in low versus high blood lead (PbB) children. MATERIAL AND METHODS: With an observational cross-sectional design, a sample of 292 children aged 6-11 years from two primary schools around a shipyard, known to be an area contaminated with lead, were examined. The number of decayed and filled surfaces on deciduous teeth (dfs) and the number of decayed, missing, and filled surfaces on permanent teeth (DMFS) were recorded. Microbiological plaque samples were taken from each child with a toothbrush. Enumeration of 17 bacterial species was carried out using the checkerboard DNA-DNA hybridization technique. RESULTS: Overall means (SD) of dfs and DMFS were 13.2 (9.5) and 1.3 (2.3), respectively. Prevalence of excessive count (>or=10(6) cells/sample) was 100% for 4 known cariogenic bacteria and over 95% in another 2 species. With Bonferroni correction for type I error adjustment, there was no significant association between the count of each bacterial species and PbB and caries experience. The checkerboard method is sensitive in bacteria detection, but may not be suitable for differentiating caries risk in the endemic population.
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| 8. |
- Youravong, Nattaporn, et al.
(författare)
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Morphology of enamel in primary teeth from children in Thailand exposed to environmental lead.
- 2005
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Ingår i: The Science of the total environment. - : Elsevier BV. - 0048-9697. ; 348:1-3, s. 73-81
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Tidskriftsartikel (refereegranskat)abstract
- Lead is one of the major environmental pollutants and a health risk. Dental hard tissues have a capacity to accumulate lead from the environment. Eighty exfoliated primary teeth were collected from children residing around a shipyard area in southern Thailand, known for its lead contamination. The morphology of the enamel was examined by polarized light microscopy (PLM), microradiography (MRG), and scanning electron microscopy (SEM). The specimens derived from two groups of children, one group with high blood levels of lead (57 teeth) and one group having low blood levels of lead (23 teeth). The enamel irrespective of group appeared normal. However, in a majority of the specimens the enamel surface appeared hypomineralized, which was confirmed in SEM. No morphological changes connected to lead in blood could be found. The hypomineralized surface zone could possibly be attributed to an acid oral environment.
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