| 1. |
- Appelgren, Linnea, et al.
(author)
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Dental plaque pH and ureolytic activity in children and adults of a low caries population
- 2014
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In: Acta Odontologica Scandinavica. - : Informa UK Limited. - 0001-6357 .- 1502-3850. ; 72:3, s. 194-201
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Journal article (peer-reviewed)abstract
- Objectives. The aim of this study was to evaluate the plaque pH level and ureolytic activity among children and adults of Karen Hill tribes. Methods. Thirty-four children aged 6-10 years and 46 adults aged 20-38 years were interviewed regarding oral hygiene practices, sucrose intake and betel chewing. Caries experience (DMFT and DT), calculus, bleeding on probing (BoP) and Plaque index (PlI) were registered. Ureolytic activity in supragingival plaque was tested at two interproximal sites (11/12 and 41/42) with the rapid urease test (RUT). Registration of plaque pH was performed at two interproximal sites (15/ 16 and 31/41) before, during and 30 min after rinsing with an urea solution (0.25%). Four interproximal plaque samples (one from each quadrant) per individual were collected to test the bacterial composition using the checkerboard technique. Results. Children and adults had similarly low DMFT and DT values. Children had a higher baseline pH and a higher ureolytic activity in the maxilla (p < 0.05) compared with adults. A significant correlation (r(2) = 0.63) was found between baseline pH and urease activity in the mandibular anterior teeth. Caries-free individuals had a higher baseline pH compared with caries active individuals in the anterior mandibular region (p < 0.01). The microbiological composition was characterized by an anaerobic low acidiogenic microbiota. Conclusions. Dental plaque pH is related to the ureolytic activity, which explains the low acidogenic plaque microflora and the low caries levels in the Karen population.
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| 2. |
- Subramani, Durai B, et al.
(author)
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Lactobacillus and Bifidobacterium species do not secrete protease that cleaves the MUC2 mucin which organises the colon mucus.
- 2010
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In: Beneficial microbes. - 1876-2891. ; 1:4, s. 343-50
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Journal article (peer-reviewed)abstract
- The colon epithelium is covered by two layers of mucus built around the MUC2 mucin. An inner dense and attached mucus layer does not allow bacteria to penetrate, thus keeping the epithelial cell surface free from bacteria. An outer loose mucus layer is the habitat for the commensal bacterial microbiota. The inner mucus layer is renewed from the epithelial side and gets converted into the outer layer due to proteolytic cleavages by host proteases. We have now analysed if potential probiotic bacteria, namely Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus bulgaricus and Bifidobacterium lactis, can secrete protease that cleaves the MUC2 mucin. We found that none of the potential probiotic bacteria Lactobacillus and Bifidobacterium could cleave the MUC2 core protein in the form of recombinant MUC2 N and C-termini although they secreted active proteases. This was in contrast to crude mixtures of oral and faecal bacteria that cleaved the MUC2 mucin. This observation further supports the view that these potential probiotic bacteria are of no harm to the host, as these bacteria cannot disrupt the mucin organised mucus as long as they are covered by glycans.
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| 3. |
- van der Post, Sjoerd, 1981, et al.
(author)
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Site-specific O-glycosylation on the MUC2 mucin protein inhibits cleavage by the Porphyromonas gingivalis secreted cysteine protease (RgpB).
- 2013
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In: The Journal of biological chemistry. - 1083-351X. ; 288:20, s. 14636-46
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Journal article (peer-reviewed)abstract
- The colonic epithelial surface is protected by an inner mucus layer that the commensal microflora cannot penetrate. We previously demonstrated that Entamoeba histolytica secretes a protease capable of dissolving this layer that is required for parasite penetration. Here, we asked whether there are bacteria that can secrete similar proteases. We screened bacterial culture supernatants for such activity using recombinant fragments of the MUC2 mucin, the major structural component, and the only gel-forming mucin in the colonic mucus. MUC2 has two central heavily O-glycosylated mucin domains that are protease-resistant and has cysteine-rich N and C termini responsible for polymerization. Culture supernatants of Porphyromonas gingivalis, a bacterium that secretes proteases responsible for periodontitis, cleaved the MUC2 C-terminal region, whereas the N-terminal region was unaffected. The active enzyme was isolated and identified as Arg-gingipain B (RgpB). Two cleavage sites were localized to IR↓TT and NR↓QA. IR↓TT cleavage will disrupt the MUC2 polymers. Because this site has two potential O-glycosylation sites, we tested whether recombinant GalNAc-transferases (GalNAc-Ts) could glycosylate a synthetic peptide covering the IRTT sequence. Only GalNAc-T3 was able to glycosylate the second Thr in IRTT, rendering the sequence resistant to cleavage by RgpB. Furthermore, when GalNAc-T3 was expressed in CHO cells expressing the MUC2 C terminus, the second threonine was glycosylated, and the protein became resistant to RgpB cleavage. These findings suggest that bacteria can produce proteases capable of dissolving the inner protective mucus layer by specific cleavages in the MUC2 mucin and that this cleavage can be modulated by site-specific O-glycosylation.
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| 4. |
- Charalampakis, Georgios, et al.
(author)
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A follow-up study of peri-implantitis cases after treatment.
- 2011
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In: Journal of clinical periodontology. - 1600-051X. ; 38:9, s. 864-71
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Journal article (peer-reviewed)abstract
- The aim of this retrospective study was to follow patient cases in a longitudinal manner after peri-implantitis treatment.
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| 5. |
- Charalampakis, Georgios, et al.
(author)
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Bacterial markers vs. clinical markers to predict progression of chronic periodontitis: a 2-yr prospective observational study
- 2013
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In: European Journal of Oral Sciences. - : Wiley. - 0909-8836. ; 121:5, s. 394-402
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Journal article (peer-reviewed)abstract
- The aim of this study was to identify sites at risk for future progression, during 2 yr of maintenance, in patients with chronic periodontitis (CP), based on longitudinal clinical and microbiological monitoring. At baseline (2003), clinical and microbiological features were recorded in 50 patients with CP. Two microbial samples were obtained from each patient (one from a clinically healthy site and one from a periodontitis site) and these were analyzed using DNA-DNA hybridization involving 25 bacterial species. After non-surgical periodontal therapy, clinical and microbiological re-examinations were performed at the same or similar sites at 2 yr (2006) and 4 yr (2008) of maintenance. Plaque, bleeding on probing (BoP), and the number of sites with periodontitis (>= 4 mm) and severe periodontitis (>= 6 mm) all showed a significant decrease at 2 and 4 yr of maintenance after non-surgical intervention. Checkerboard analysis revealed that various bacteria with a high colonization score (>= 3) corroborated the clinical findings of pathology at 2003, 2006, and 2008. Different clusters of bacteria, not just the 'red complex', were able to predict progression of chronic periodontitis during 2 yr of maintenance (2006-2008). Therefore, quantified bacterial markers (reflecting bacterial load) and the clinical markers BoP and periodontal probing depth show comparable prediction of future disease condition.
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| 6. |
- Charalampakis, Georgios, et al.
(author)
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Clinical and microbiological characteristics of peri-implantitis cases: a retrospective multicentre study.
- 2012
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In: Clinical oral implants research. - : Wiley. - 0905-7161. ; 23:9, s. 1045-1054
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Journal article (peer-reviewed)abstract
- OBJECTIVES: The aim of this study was to follow patient cases retrospectively in a longitudinal manner from the time of implant placement to the time they were diagnosed with peri-implant disease, and to identify associated clinical and microbiological features of peri-implant disease. MATERIAL AND METHODS: A total of 281 patient cases were chosen from the archives of the Oral Microbiological Diagnostic Laboratory, Gothenburg, Sweden, based on bacterial samples taken from diseased implants. A form was designed and filled in separately for each case including data on patient, implant and disease profile. RESULTS: Most cases were severe peri-implantitis cases (91.4%). In 41.3% of the patients, peri-implantitis was developed early, already after having implants in function less than 4years. The type of implant surface was significantly associated with the time in years implants were in function, before disease was developed (P<0.05). The microbiological results by both culture and checkerboard analysis, although failed to fully correspond to the severity of the disease in terms of magnitude, proved to show that peri-implantitis is a polymicrobial anaerobic infection with increased number of AGNB (aerobic Gram-negative bacilli) in 18.6% of the patients. CONCLUSIONS: Peri-implantitis is a biological complication of implants in function that poses a threat to their long-term survival. It may develop earlier around implants with rough surfaces and it may represent a true infection. Microbiological sampling methods should be improved and uniformed so as to fully unveil the microbiological profile of the disease.
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| 7. |
- Charalampakis, Georgios, et al.
(author)
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Microbiota in experimental periodontitis and peri-implantitis in dogs
- 2014
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In: Clinical Oral Implants Research. - : Wiley. - 0905-7161. ; 25:9, s. 1094-1098
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Journal article (peer-reviewed)abstract
- Aim To analyze the microbial profile around teeth and implants following ligature removal in experimental periodontitis and peri-implantitis in dogs. Material and methods Four implants with similar geometry and with two different surface characteristics (implant A: turned/implant B: TiUnite; NobelBiocare AB) were placed pairwise in the right side of the mandible 3 months after tooth extraction in five dogs. Experimental periodontitis and peri-implantitis were initiated 3 months later by ligature placement around implants and mandibular premolars and plaque formation. The ligatures were removed after 10 weeks. Microbial samples were obtained using paper points immediately after ligature removal, at 10 and 25 weeks after ligature removal. The microbiological analysis was performed by “checkerboard” DNA-DNA hybridization, including a panel of 16 bacterial species. Results The amount of bone loss that occurred during the period following ligature removal was significantly larger at implants with a modified surface than at implants with a turned surface and at teeth. The microbiological analysis revealed that the total bacterial load increased during the period following ligature removal and established an anaerobic Gram-negative microflora. Conclusion It is suggested that the large variation in regard to the microbial profiles makes interpretation of a correlation between disease progression and microbial profiles difficult.
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| 8. |
- Charalampakis, Georgios, et al.
(author)
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Rationale for treatment of oral infectious diseases based on a micro-ecological concept
- 2014
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In: Current Trends in Microbiology. - 0972-7736. ; 9
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Research review (peer-reviewed)abstract
- The most common oral infectious diseases are caries, endodontic infections, periodontitis and peri-implantitis. Early diagnosis and total control of these conditions remain a major challenge for clinicians. In this review, we describe infectious oral diseases and evaluate critically the current treatment strategies using a holistic aetiological approach. We draw attention to the local environment, the micro-ecology, where opportunistic pathogens may survive and thrive. We explain why elimination of bacteria from the disease site is probably not feasible and may not be critical; acceptance of this idea would represent a paradigm shift in understanding these conditions. We demonstrate that a crucial step for long-term success of treatment interventions and shift from disease to health involves a change in the local environment to create conditions in which pathogenic bacteria cannot survive and grow. We argue that measures that do not entail local micro-ecological change at affected sites will fail to prevent the recurrence of infectious oral diseases. Our further hope is that the idea of micro-ecology in dentistry will provide a model and pedagogical tool that will help clinicians, in their quest to counter oral diseases of infectious origin, to evaluate treatment approaches in dental care.
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| 9. |
- Dahlén, Gunnar, 1944, et al.
(author)
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A microbiological study in relation to the presence of caries and calculus.
- 2010
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In: Acta odontologica Scandinavica. - : Informa UK Limited. - 1502-3850 .- 0001-6357. ; 68:4, s. 199-206
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Journal article (peer-reviewed)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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| 10. |
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