Michel Sixou - Academia.edu (original) (raw)
Papers by Michel Sixou
Methods for analysing dental caries and associated risk indicators have evolved considerably in r... more Methods for analysing dental caries and associated risk indicators have evolved considerably in recent decades. The use of zero-inflated or hurdle models is increasing so as to take account of the decayed, missing, and filled teeth (DMFT) distribution, which is positively skewed and has a high proportion of zero scores. However, there is a need to develop new statistical models that involve pragmatic biological considerations on dental caries in epidemiological surveys. In this paper, we show that the zero-inflated and the hurdle models can both be expressed as a compound sum. Using the same compound sum, we then present the generalized negative binomial (GNB) distribution for dental caries count data, and provide a numerical application using the data of the EPIPAP study. The GNB model generates the best score functions while handling the lifetime dental caries disease process better. In conclusion, the GNB model suits the nature of some count data, in particular when structural zeros are unlikely to occur and when several latent spells can lead to new countable events. For these reasons, the use of the GNB distribution appears to be relevant for the modelling of dental caries count data.
PubMed, Sep 1, 2001
The study on the sensitiveness of slow-growing anaerobes bacteria to antibiotics is delicate when... more The study on the sensitiveness of slow-growing anaerobes bacteria to antibiotics is delicate when you consider the technical motives that make it difficult to transpose the standard methods frequently used in microbiological laboratories. The three main methods used to determine susceptibility to antibiotics are: disk-diffusion test, antibiotics containing microdilution plates and ATB ANA (bioMérieux). The aim of this study is to compare the effectiveness of each of these methods on severe anaerobes bacteria isolated in sub-gingival flora of patients suffering from developing periodontitis (rapidly progressive periodontitis, refractory periodontitis, active stage of adult chronic periodontitis). The observed bacteria are: Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Campylobacter rectus, Peptostreptococcus micros. Antibiotics used are: ampicilline, amoxicilline, tetracycline, erythromycine, metronidazole. The comparison of the minimal inhibitory concentrations (M.I.C) of each of these methods has permitted to show a strict correlation in the results observed with these three methods, if only the growth of the severe anaerobes bacteria on agar medium does not exceed 72 hours.
PubMed, Jun 1, 1991
The aim of this investigation was to study the transmission of Actinobacillus actinomycetemcomita... more The aim of this investigation was to study the transmission of Actinobacillus actinomycetemcomitans (A.a) between husband and wife when one of them was affected by acute juvenile periodontitis (P.A.J.). The hypothesis tested was the role played by the reservoir of the non-infected partner in explaining the frequent recurrences of the disease in the affected spouse despite combined antibiotherapeutical and surgical treatments. Twenty subjects with P.A.J. were studied. A.a. was found in the sub-gingival flora of nineteen of them. This micro-organism was also isolated in each of the partners of the nineteen patients. Each couple presented strains of the same biotype. The serotypes were studied in seven of these couples and confirmed the results of the biotypes. All theses results are in favour of the transmission of A.a. between partners.
PubMed, Sep 1, 1992
Adherence is a major pathogenicity factor for many bacteria. The aim of this study was to measure... more Adherence is a major pathogenicity factor for many bacteria. The aim of this study was to measure the adherence potential of Actinobacillus actinomycetemcomitans (A.a.) for buccal epithelial cells (BEC). In the second part of the study, the inhibitory potential of saliva on adherence between A.a. and BEC was tested. Saliva specimens were obtained from three groups of subjects: a group of normal subjects (NS), a group of subject with localized juvenile periodontitis (LJPS) and a group of subjects with adult periodontitis (APS). Clinical strains of A.a. showed a major adherence potential for BEC (25.5 A.a./BEC). In contrast, reference strains of bacteria appeared to possess a much lower potential for adherence (12.6 A.a./BEC). Saliva samples taken from from the LJPS and APS group had a high inhibitory adherence potential, since in each of these groups a reduction of 60.9% and 66.7% respectively, was observed in the number of bacteria adhering to BEC.
PubMed, Jun 1, 2004
The mechanical elimination of the bacteria plaque is the basis of the prevention and the treatmen... more The mechanical elimination of the bacteria plaque is the basis of the prevention and the treatment of gingivitis and periodontitis. Chemicals products used in the control of supra and subgingival plaque show a great importance because of individual and professional difficulties which constitute an impediment to the effective elimination of the bacteria plaque. However, by this time, there's no miracle product for oral hygiene capable at long term to take over from the tooth-brush and paste. The use at long term of chemicals in the bacteria plaque control can't be recommended because of their following effects and their slight effectivity-cost ratio. Nevertheless, oral hygiene chemicals combined with mechanical treatment provide very good results. Particularly, when used in the form of subgingival irrigation or slow liberation materials set in the periodontal pocket.
PubMed, Mar 1, 2002
Chlorhexidine is an antibacterial agent of the bisguanide family. It's the most effectual molecul... more Chlorhexidine is an antibacterial agent of the bisguanide family. It's the most effectual molecule of all antiseptics for oral use. Because of its so frequent use, we have elaborated a protocol in order to estimate the resistance of the sub-gingival flora bacteria to its actions. We have determined the minimal inhibitory concentration of the different observed bacteria species and, have from that stage, progressively increased the concentration at a rate of 5 micrograms/ml. The obtained results show that the bacteria can undergo structural and/or biochemical alterations to adapt to more significant concentrations.
PubMed, Sep 1, 1991
The prevalence and distribution of Haemophilus actinomycetemcomitans (H.a.) were studied in 3292 ... more The prevalence and distribution of Haemophilus actinomycetemcomitans (H.a.) were studied in 3292 specimens of subgingival plaque on the four subgingival aspects of all teeth of the dental arch, 150 specimens from the mucosal surface (tongue and cheek) and 30 saliva specimens in 30 subjects. The sample population of 30 subjects was subdivided into three groups: 10 normal subjects, 10 subjects with localised juvenile periodontitis (SLJP) and 10 subjects with adult chronic periodontitis (SACP). The prevalences of H.a. in subgingival areas of each group mentioned were 30%, 90% and 60% respectively. Scores for prevalence obtained with other types of specimens proved to be lower except for saliva specimens which appear to be a less representative marker of subgingival prevalence of H.a.. Histograms for the distribution of H.a. revealed a predominance of this microorganism on the proximal surface of molar teeth in the three groups of patients. Only the SLJP also exhibited a high prevalence on the proximal aspect of the incisor teeth. The wide distribution of H.a. in all of the clinical groups studied suggests that this bacterium is not a good marker of periodontal disease and that it is necessary to define the most characteristic phenotypes and genotypes.
PubMed, Jun 1, 2002
The Nitida Kola is a substance extracted from the kolanut. In West Africa its use by chewing is w... more The Nitida Kola is a substance extracted from the kolanut. In West Africa its use by chewing is widespread among the Manding people. It's said to have tonic, stimulant and aphrodisiac characteristics and even recent studies have shown that it has antibacterial characteristics. The aim of this study is to make an estimation of the Nitida Kola's effects on different bacterial species involved in the two main oral and dental pathologies (teeth decays and periodontal illnesses). The obtained results indicate that the kola extract is not effectual against the tried-out bacteria at regular dose used by chewing.
PubMed, Mar 1, 2011
Background: Helicobacter pylori plays a significant role in gastric disease. The aim of the prese... more Background: Helicobacter pylori plays a significant role in gastric disease. The aim of the present pilot study was to evaluate the prevalence of H. pylori detected by real-time polymerase chain reaction (real-time PCR) in the sub-gingival plaque of chronic periodontitis patients and to determine periodontopathogens profile of positive sites at H. pylori. Methodology: 109 subgingival samples collected from 17 subjects with chronic periodontitis were studied. The DNA was extracted from the oral samples and analyzed for the presence of H. pylori by real-time PCR (LightCycler) using 16S rRNA#120 primers which targeted the 16S rRNA gene. DNA from H. pylori DSM 4867 was used as a positive control. Seven bacteria implicated in chronic periodontitis were selected to explore the presence of these periodontopathic species in the oral positive sites for H. pylori. Results: 16 of 109 samples (14.7%) were positives of H. pylori. All the positives sites were also positives to Fusobacterium nucleatum and Eikenella corrodens, 62.5% to Porphyromonas gingivalis, 31.25% to Treponema denticola, 25% to Prevotella intermedia, 12.5% to Aggregatibacter actinomycetemcomitans and 6.25% to Tannerella forsythia. Conclusions: H. pylori may be present in the subgingival plaque samples of patients with chronic periodontitis who are resident in a developing country. F. nucleatum and E. corrodens could coaggregate with H. pylori in the subgingival dental plaque.
Oral Microbiology and Immunology, Aug 1, 2005
The frequent use of antibiotics in developed countries has led to the emergence of widespread bac... more The frequent use of antibiotics in developed countries has led to the emergence of widespread bacterial resistance. In this study, the interindividual variability of the antibiotic susceptibility of 50 putative microorganisms in aggressive periodontitis patients has been evaluated by means of VC (variation coefficient). A total of 60 microbial samples were collected from 20 adult patients diagnosed with aggressive periodontitis (2-4 samples by patient). Bacterial strains of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum, and Peptostreptococcus micros were isolated according to Slots' rapid identification method. The susceptibilities to 10 antibiotics were studied: penicillin G (PEN), ampicillin (AMP), amoxicillin (AMX), amoxicillin/clavulanate (AMC), tetracycline (TET), doxycycline (DOX), ciprofloxacin (CIP), erythromycin (ERY), spiramycin (SPI) and clindamycin (CLIN), using the Disk Diffusion Susceptibility test (DDS test: Kirby-Bauer's modified method for anaerobic bacteria). The broth microdilution Minimum Inhibitory Concentration test was carried out as a control test. Among the 50 identified bacteria, 15 were P. gingivalis, 12 P. intermedia, 8 T. forsythia, 9 F. nucleatum, and 6 P. micros. The results of the DDS test show that penicillins (especially AMC, AMP, and AMX), cyclines (especially DOX) and CLIN are highly effective against the 50 anaerobic studied bacteria. CIP and ERY have the lowest efficacy against those bacteria. CIP shows a very variable activity according to anaerobic bacteria species, being particularly inactive against P. gingivalis and very efficient against T. forsythia and P. micros. SPI is also highly efficient but not against P. micros. The interindividual susceptibility of principal periodontal pathogens to antibiotics is not homogeneous and seems to vary according to bacterial species and antimicrobial molecules. This variability seems to be greater with older molecules (PEN, TET, ERY) than with more recent ones, which indicates more stable results (AMC, AMX, AMP, and DOX). P. intermedia appeared to be the bacteria most resistant to penicillins and showed the highest coefficient variation. Together with scaling and root planing, the combination of two antibiotics would therefore seem to be recommended in the treatment of aggressive periodontitis, particularly in the presence of P. intermedia.
PubMed, Mar 1, 1991
A comparative study of four classical techniques employed in the sampling of subgingival microflo... more A comparative study of four classical techniques employed in the sampling of subgingival microflora (paper points, swabbing, curette and washing followed by aspiration) has been carried out. This study was based upon quantitative criteria (number of bacteria sampled) and qualitative criteria (number of morphologically distinct colonies found per sampling technique). Sampling was done on three different groups of patients: a control group, a group of patients with gingivitis and a group of patients with periodontitis. The curette sampling technique was found to be efficient both quantitatively and qualitatively. Difficulties in standardizing this method however were encountered with the failure to achieve reproducible results. For this reason the technique of paper point was preferred. This method was found to be more reliable and reproducible in each of the three groups of patients sampled.
HAL (Le Centre pour la Communication Scientifique Directe), 2009
Human Immunology, Apr 1, 1996
Several HLA class I alleles have been shown to downregulate the activity of natural killer (NK) c... more Several HLA class I alleles have been shown to downregulate the activity of natural killer (NK) cells in a specific way and recent data indicate that some T cells may be downregulated in the same way. In order to control the expression of certain HLA class I antigens on ...
The Journal of Immunology
We used flow cytometry to analyze the expression of adhesion molecules and the oxidative burst of... more We used flow cytometry to analyze the expression of adhesion molecules and the oxidative burst of whole-blood polymorphonuclear neutrophils (PMN) from 26 patients with periodontitis. Three different clinical entities were studied: adult periodontitis (AP), localized juvenile periodontitis (LJP), and rapidly progressive periodontitis (RPP). Unstimulated PMN from the patients showed reduced Lewis x, sialyl-Lewis x, and L-selectin expression relative to those from healthy control subjects. These alterations were present whatever the severity of periodontal disease. However, PMN from RPP patients showed increased basal H2O2 production and decreased L-selectin shedding. These latter impairments, which correlated with increased IL-8 plasma levels, could contribute to initial vascular damage. In addition, decreased IL-8 priming of H2O2 production by PMN from RPP patients could account for a lower bactericidal capacity of PMN, leading to the large number of bacteria in the subgingival regio...
Methods for analysing dental caries and associated risk indicators have evolved considerably in r... more Methods for analysing dental caries and associated risk indicators have evolved considerably in recent decades. The use of zero-inflated or hurdle models is increasing so as to take account of the decayed, missing, and filled teeth (DMFT) distribution, which is positively skewed and has a high proportion of zero scores. However, there is a need to develop new statistical models that involve pragmatic biological considerations on dental caries in epidemiological surveys. In this paper, we show that the zero-inflated and the hurdle models can both be expressed as a compound sum. Using the same compound sum, we then present the generalized negative binomial (GNB) distribution for dental caries count data, and provide a numerical application using the data of the EPIPAP study. The GNB model generates the best score functions while handling the lifetime dental caries disease process better. In conclusion, the GNB model suits the nature of some count data, in particular when structural zeros are unlikely to occur and when several latent spells can lead to new countable events. For these reasons, the use of the GNB distribution appears to be relevant for the modelling of dental caries count data.
Infection and Immunity, 1994
A geographically homogeneous population of 83 subjects, from 21 families with localized juvenile ... more A geographically homogeneous population of 83 subjects, from 21 families with localized juvenile periodontitis (LJP), and 35 healthy control subjects was monitored, over a 5-year period, for the presence of the periodontal pathogen Actinobacillus actinomycetemcomitans. Restriction fragment length polymorphism (RFLP) analysis was used to monitor the distribution of genetic variants of this bacterium in LJP-susceptible subjects that converted from a healthy to a diseased periodontal status. A. actinomycetemcomitans was cultured from 57% of the LJP family members accessioned into the study. Nine of 36 LJP-susceptible subjects, in seven families, developed signs of periodontal destruction. All but one of these conversion subjects harbored A. actinomycetemcomitans. Bacterial variants representative of a single RFLP group (II) showed the strongest correlation with conversion (P < 0.002). Six of nine conversion subjects were infected with A. actinomycetemcomitans from this group. RFLP g...
Journal de biologie buccale, 1991
The prevalence and distribution of Haemophilus actinomycetemcomitans (H.a.) were studied in 3292 ... more The prevalence and distribution of Haemophilus actinomycetemcomitans (H.a.) were studied in 3292 specimens of subgingival plaque on the four subgingival aspects of all teeth of the dental arch, 150 specimens from the mucosal surface (tongue and cheek) and 30 saliva specimens in 30 subjects. The sample population of 30 subjects was subdivided into three groups: 10 normal subjects, 10 subjects with localised juvenile periodontitis (SLJP) and 10 subjects with adult chronic periodontitis (SACP). The prevalences of H.a. in subgingival areas of each group mentioned were 30%, 90% and 60% respectively. Scores for prevalence obtained with other types of specimens proved to be lower except for saliva specimens which appear to be a less representative marker of subgingival prevalence of H.a.. Histograms for the distribution of H.a. revealed a predominance of this microorganism on the proximal surface of molar teeth in the three groups of patients. Only the SLJP also exhibited a high prevalence...
Human Immunology, 1996
Several HLA class I alleles have been shown to downregulate the activity of natural killer (NK) c... more Several HLA class I alleles have been shown to downregulate the activity of natural killer (NK) cells in a specific way and recent data indicate that some T cells may be downregulated in the same way. In order to control the expression of certain HLA class I antigens on ...
Journal of Dental Research, 2010
Three-dimensional imaging of teeth will increase its impact in clinical practice if reconstructio... more Three-dimensional imaging of teeth will increase its impact in clinical practice if reconstructions are metrically accurate. We hypothesized that, with cone beam computed tomography (CBCT) data, three-dimensional images of teeth can be reconstructed with the same accuracy and precision as with in vitro micro-computed tomography (micro-CT) data acquisition, the current reference standard. We used a sample of CBCT and micro-CT data taken of tooth germs. Volumes obtained with CBCT and micro-CT devices were statistically similar (n = 120, Passing-Bablok regression). Geometric deviations between CBCT and micro-CT three-dimensional surface reconstructions did not show any areas of important and systematic errors. Future investigations with the use of larger samples may also demonstrate that CBCT data will be helpful for a more in-depth study of other aspects of dental morphology—for example, assessing tooth development. With sufficient accuracy for clinical situations, potential future me...
Methods for analysing dental caries and associated risk indicators have evolved considerably in r... more Methods for analysing dental caries and associated risk indicators have evolved considerably in recent decades. The use of zero-inflated or hurdle models is increasing so as to take account of the decayed, missing, and filled teeth (DMFT) distribution, which is positively skewed and has a high proportion of zero scores. However, there is a need to develop new statistical models that involve pragmatic biological considerations on dental caries in epidemiological surveys. In this paper, we show that the zero-inflated and the hurdle models can both be expressed as a compound sum. Using the same compound sum, we then present the generalized negative binomial (GNB) distribution for dental caries count data, and provide a numerical application using the data of the EPIPAP study. The GNB model generates the best score functions while handling the lifetime dental caries disease process better. In conclusion, the GNB model suits the nature of some count data, in particular when structural zeros are unlikely to occur and when several latent spells can lead to new countable events. For these reasons, the use of the GNB distribution appears to be relevant for the modelling of dental caries count data.
PubMed, Sep 1, 2001
The study on the sensitiveness of slow-growing anaerobes bacteria to antibiotics is delicate when... more The study on the sensitiveness of slow-growing anaerobes bacteria to antibiotics is delicate when you consider the technical motives that make it difficult to transpose the standard methods frequently used in microbiological laboratories. The three main methods used to determine susceptibility to antibiotics are: disk-diffusion test, antibiotics containing microdilution plates and ATB ANA (bioMérieux). The aim of this study is to compare the effectiveness of each of these methods on severe anaerobes bacteria isolated in sub-gingival flora of patients suffering from developing periodontitis (rapidly progressive periodontitis, refractory periodontitis, active stage of adult chronic periodontitis). The observed bacteria are: Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Campylobacter rectus, Peptostreptococcus micros. Antibiotics used are: ampicilline, amoxicilline, tetracycline, erythromycine, metronidazole. The comparison of the minimal inhibitory concentrations (M.I.C) of each of these methods has permitted to show a strict correlation in the results observed with these three methods, if only the growth of the severe anaerobes bacteria on agar medium does not exceed 72 hours.
PubMed, Jun 1, 1991
The aim of this investigation was to study the transmission of Actinobacillus actinomycetemcomita... more The aim of this investigation was to study the transmission of Actinobacillus actinomycetemcomitans (A.a) between husband and wife when one of them was affected by acute juvenile periodontitis (P.A.J.). The hypothesis tested was the role played by the reservoir of the non-infected partner in explaining the frequent recurrences of the disease in the affected spouse despite combined antibiotherapeutical and surgical treatments. Twenty subjects with P.A.J. were studied. A.a. was found in the sub-gingival flora of nineteen of them. This micro-organism was also isolated in each of the partners of the nineteen patients. Each couple presented strains of the same biotype. The serotypes were studied in seven of these couples and confirmed the results of the biotypes. All theses results are in favour of the transmission of A.a. between partners.
PubMed, Sep 1, 1992
Adherence is a major pathogenicity factor for many bacteria. The aim of this study was to measure... more Adherence is a major pathogenicity factor for many bacteria. The aim of this study was to measure the adherence potential of Actinobacillus actinomycetemcomitans (A.a.) for buccal epithelial cells (BEC). In the second part of the study, the inhibitory potential of saliva on adherence between A.a. and BEC was tested. Saliva specimens were obtained from three groups of subjects: a group of normal subjects (NS), a group of subject with localized juvenile periodontitis (LJPS) and a group of subjects with adult periodontitis (APS). Clinical strains of A.a. showed a major adherence potential for BEC (25.5 A.a./BEC). In contrast, reference strains of bacteria appeared to possess a much lower potential for adherence (12.6 A.a./BEC). Saliva samples taken from from the LJPS and APS group had a high inhibitory adherence potential, since in each of these groups a reduction of 60.9% and 66.7% respectively, was observed in the number of bacteria adhering to BEC.
PubMed, Jun 1, 2004
The mechanical elimination of the bacteria plaque is the basis of the prevention and the treatmen... more The mechanical elimination of the bacteria plaque is the basis of the prevention and the treatment of gingivitis and periodontitis. Chemicals products used in the control of supra and subgingival plaque show a great importance because of individual and professional difficulties which constitute an impediment to the effective elimination of the bacteria plaque. However, by this time, there's no miracle product for oral hygiene capable at long term to take over from the tooth-brush and paste. The use at long term of chemicals in the bacteria plaque control can't be recommended because of their following effects and their slight effectivity-cost ratio. Nevertheless, oral hygiene chemicals combined with mechanical treatment provide very good results. Particularly, when used in the form of subgingival irrigation or slow liberation materials set in the periodontal pocket.
PubMed, Mar 1, 2002
Chlorhexidine is an antibacterial agent of the bisguanide family. It's the most effectual molecul... more Chlorhexidine is an antibacterial agent of the bisguanide family. It's the most effectual molecule of all antiseptics for oral use. Because of its so frequent use, we have elaborated a protocol in order to estimate the resistance of the sub-gingival flora bacteria to its actions. We have determined the minimal inhibitory concentration of the different observed bacteria species and, have from that stage, progressively increased the concentration at a rate of 5 micrograms/ml. The obtained results show that the bacteria can undergo structural and/or biochemical alterations to adapt to more significant concentrations.
PubMed, Sep 1, 1991
The prevalence and distribution of Haemophilus actinomycetemcomitans (H.a.) were studied in 3292 ... more The prevalence and distribution of Haemophilus actinomycetemcomitans (H.a.) were studied in 3292 specimens of subgingival plaque on the four subgingival aspects of all teeth of the dental arch, 150 specimens from the mucosal surface (tongue and cheek) and 30 saliva specimens in 30 subjects. The sample population of 30 subjects was subdivided into three groups: 10 normal subjects, 10 subjects with localised juvenile periodontitis (SLJP) and 10 subjects with adult chronic periodontitis (SACP). The prevalences of H.a. in subgingival areas of each group mentioned were 30%, 90% and 60% respectively. Scores for prevalence obtained with other types of specimens proved to be lower except for saliva specimens which appear to be a less representative marker of subgingival prevalence of H.a.. Histograms for the distribution of H.a. revealed a predominance of this microorganism on the proximal surface of molar teeth in the three groups of patients. Only the SLJP also exhibited a high prevalence on the proximal aspect of the incisor teeth. The wide distribution of H.a. in all of the clinical groups studied suggests that this bacterium is not a good marker of periodontal disease and that it is necessary to define the most characteristic phenotypes and genotypes.
PubMed, Jun 1, 2002
The Nitida Kola is a substance extracted from the kolanut. In West Africa its use by chewing is w... more The Nitida Kola is a substance extracted from the kolanut. In West Africa its use by chewing is widespread among the Manding people. It's said to have tonic, stimulant and aphrodisiac characteristics and even recent studies have shown that it has antibacterial characteristics. The aim of this study is to make an estimation of the Nitida Kola's effects on different bacterial species involved in the two main oral and dental pathologies (teeth decays and periodontal illnesses). The obtained results indicate that the kola extract is not effectual against the tried-out bacteria at regular dose used by chewing.
PubMed, Mar 1, 2011
Background: Helicobacter pylori plays a significant role in gastric disease. The aim of the prese... more Background: Helicobacter pylori plays a significant role in gastric disease. The aim of the present pilot study was to evaluate the prevalence of H. pylori detected by real-time polymerase chain reaction (real-time PCR) in the sub-gingival plaque of chronic periodontitis patients and to determine periodontopathogens profile of positive sites at H. pylori. Methodology: 109 subgingival samples collected from 17 subjects with chronic periodontitis were studied. The DNA was extracted from the oral samples and analyzed for the presence of H. pylori by real-time PCR (LightCycler) using 16S rRNA#120 primers which targeted the 16S rRNA gene. DNA from H. pylori DSM 4867 was used as a positive control. Seven bacteria implicated in chronic periodontitis were selected to explore the presence of these periodontopathic species in the oral positive sites for H. pylori. Results: 16 of 109 samples (14.7%) were positives of H. pylori. All the positives sites were also positives to Fusobacterium nucleatum and Eikenella corrodens, 62.5% to Porphyromonas gingivalis, 31.25% to Treponema denticola, 25% to Prevotella intermedia, 12.5% to Aggregatibacter actinomycetemcomitans and 6.25% to Tannerella forsythia. Conclusions: H. pylori may be present in the subgingival plaque samples of patients with chronic periodontitis who are resident in a developing country. F. nucleatum and E. corrodens could coaggregate with H. pylori in the subgingival dental plaque.
Oral Microbiology and Immunology, Aug 1, 2005
The frequent use of antibiotics in developed countries has led to the emergence of widespread bac... more The frequent use of antibiotics in developed countries has led to the emergence of widespread bacterial resistance. In this study, the interindividual variability of the antibiotic susceptibility of 50 putative microorganisms in aggressive periodontitis patients has been evaluated by means of VC (variation coefficient). A total of 60 microbial samples were collected from 20 adult patients diagnosed with aggressive periodontitis (2-4 samples by patient). Bacterial strains of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum, and Peptostreptococcus micros were isolated according to Slots' rapid identification method. The susceptibilities to 10 antibiotics were studied: penicillin G (PEN), ampicillin (AMP), amoxicillin (AMX), amoxicillin/clavulanate (AMC), tetracycline (TET), doxycycline (DOX), ciprofloxacin (CIP), erythromycin (ERY), spiramycin (SPI) and clindamycin (CLIN), using the Disk Diffusion Susceptibility test (DDS test: Kirby-Bauer's modified method for anaerobic bacteria). The broth microdilution Minimum Inhibitory Concentration test was carried out as a control test. Among the 50 identified bacteria, 15 were P. gingivalis, 12 P. intermedia, 8 T. forsythia, 9 F. nucleatum, and 6 P. micros. The results of the DDS test show that penicillins (especially AMC, AMP, and AMX), cyclines (especially DOX) and CLIN are highly effective against the 50 anaerobic studied bacteria. CIP and ERY have the lowest efficacy against those bacteria. CIP shows a very variable activity according to anaerobic bacteria species, being particularly inactive against P. gingivalis and very efficient against T. forsythia and P. micros. SPI is also highly efficient but not against P. micros. The interindividual susceptibility of principal periodontal pathogens to antibiotics is not homogeneous and seems to vary according to bacterial species and antimicrobial molecules. This variability seems to be greater with older molecules (PEN, TET, ERY) than with more recent ones, which indicates more stable results (AMC, AMX, AMP, and DOX). P. intermedia appeared to be the bacteria most resistant to penicillins and showed the highest coefficient variation. Together with scaling and root planing, the combination of two antibiotics would therefore seem to be recommended in the treatment of aggressive periodontitis, particularly in the presence of P. intermedia.
PubMed, Mar 1, 1991
A comparative study of four classical techniques employed in the sampling of subgingival microflo... more A comparative study of four classical techniques employed in the sampling of subgingival microflora (paper points, swabbing, curette and washing followed by aspiration) has been carried out. This study was based upon quantitative criteria (number of bacteria sampled) and qualitative criteria (number of morphologically distinct colonies found per sampling technique). Sampling was done on three different groups of patients: a control group, a group of patients with gingivitis and a group of patients with periodontitis. The curette sampling technique was found to be efficient both quantitatively and qualitatively. Difficulties in standardizing this method however were encountered with the failure to achieve reproducible results. For this reason the technique of paper point was preferred. This method was found to be more reliable and reproducible in each of the three groups of patients sampled.
HAL (Le Centre pour la Communication Scientifique Directe), 2009
Human Immunology, Apr 1, 1996
Several HLA class I alleles have been shown to downregulate the activity of natural killer (NK) c... more Several HLA class I alleles have been shown to downregulate the activity of natural killer (NK) cells in a specific way and recent data indicate that some T cells may be downregulated in the same way. In order to control the expression of certain HLA class I antigens on ...
The Journal of Immunology
We used flow cytometry to analyze the expression of adhesion molecules and the oxidative burst of... more We used flow cytometry to analyze the expression of adhesion molecules and the oxidative burst of whole-blood polymorphonuclear neutrophils (PMN) from 26 patients with periodontitis. Three different clinical entities were studied: adult periodontitis (AP), localized juvenile periodontitis (LJP), and rapidly progressive periodontitis (RPP). Unstimulated PMN from the patients showed reduced Lewis x, sialyl-Lewis x, and L-selectin expression relative to those from healthy control subjects. These alterations were present whatever the severity of periodontal disease. However, PMN from RPP patients showed increased basal H2O2 production and decreased L-selectin shedding. These latter impairments, which correlated with increased IL-8 plasma levels, could contribute to initial vascular damage. In addition, decreased IL-8 priming of H2O2 production by PMN from RPP patients could account for a lower bactericidal capacity of PMN, leading to the large number of bacteria in the subgingival regio...
Methods for analysing dental caries and associated risk indicators have evolved considerably in r... more Methods for analysing dental caries and associated risk indicators have evolved considerably in recent decades. The use of zero-inflated or hurdle models is increasing so as to take account of the decayed, missing, and filled teeth (DMFT) distribution, which is positively skewed and has a high proportion of zero scores. However, there is a need to develop new statistical models that involve pragmatic biological considerations on dental caries in epidemiological surveys. In this paper, we show that the zero-inflated and the hurdle models can both be expressed as a compound sum. Using the same compound sum, we then present the generalized negative binomial (GNB) distribution for dental caries count data, and provide a numerical application using the data of the EPIPAP study. The GNB model generates the best score functions while handling the lifetime dental caries disease process better. In conclusion, the GNB model suits the nature of some count data, in particular when structural zeros are unlikely to occur and when several latent spells can lead to new countable events. For these reasons, the use of the GNB distribution appears to be relevant for the modelling of dental caries count data.
Infection and Immunity, 1994
A geographically homogeneous population of 83 subjects, from 21 families with localized juvenile ... more A geographically homogeneous population of 83 subjects, from 21 families with localized juvenile periodontitis (LJP), and 35 healthy control subjects was monitored, over a 5-year period, for the presence of the periodontal pathogen Actinobacillus actinomycetemcomitans. Restriction fragment length polymorphism (RFLP) analysis was used to monitor the distribution of genetic variants of this bacterium in LJP-susceptible subjects that converted from a healthy to a diseased periodontal status. A. actinomycetemcomitans was cultured from 57% of the LJP family members accessioned into the study. Nine of 36 LJP-susceptible subjects, in seven families, developed signs of periodontal destruction. All but one of these conversion subjects harbored A. actinomycetemcomitans. Bacterial variants representative of a single RFLP group (II) showed the strongest correlation with conversion (P < 0.002). Six of nine conversion subjects were infected with A. actinomycetemcomitans from this group. RFLP g...
Journal de biologie buccale, 1991
The prevalence and distribution of Haemophilus actinomycetemcomitans (H.a.) were studied in 3292 ... more The prevalence and distribution of Haemophilus actinomycetemcomitans (H.a.) were studied in 3292 specimens of subgingival plaque on the four subgingival aspects of all teeth of the dental arch, 150 specimens from the mucosal surface (tongue and cheek) and 30 saliva specimens in 30 subjects. The sample population of 30 subjects was subdivided into three groups: 10 normal subjects, 10 subjects with localised juvenile periodontitis (SLJP) and 10 subjects with adult chronic periodontitis (SACP). The prevalences of H.a. in subgingival areas of each group mentioned were 30%, 90% and 60% respectively. Scores for prevalence obtained with other types of specimens proved to be lower except for saliva specimens which appear to be a less representative marker of subgingival prevalence of H.a.. Histograms for the distribution of H.a. revealed a predominance of this microorganism on the proximal surface of molar teeth in the three groups of patients. Only the SLJP also exhibited a high prevalence...
Human Immunology, 1996
Several HLA class I alleles have been shown to downregulate the activity of natural killer (NK) c... more Several HLA class I alleles have been shown to downregulate the activity of natural killer (NK) cells in a specific way and recent data indicate that some T cells may be downregulated in the same way. In order to control the expression of certain HLA class I antigens on ...
Journal of Dental Research, 2010
Three-dimensional imaging of teeth will increase its impact in clinical practice if reconstructio... more Three-dimensional imaging of teeth will increase its impact in clinical practice if reconstructions are metrically accurate. We hypothesized that, with cone beam computed tomography (CBCT) data, three-dimensional images of teeth can be reconstructed with the same accuracy and precision as with in vitro micro-computed tomography (micro-CT) data acquisition, the current reference standard. We used a sample of CBCT and micro-CT data taken of tooth germs. Volumes obtained with CBCT and micro-CT devices were statistically similar (n = 120, Passing-Bablok regression). Geometric deviations between CBCT and micro-CT three-dimensional surface reconstructions did not show any areas of important and systematic errors. Future investigations with the use of larger samples may also demonstrate that CBCT data will be helpful for a more in-depth study of other aspects of dental morphology—for example, assessing tooth development. With sufficient accuracy for clinical situations, potential future me...