Scientific Rationale for Study: The oral hygiene phase is an integral part of periodontal therapy... more Scientific Rationale for Study: The oral hygiene phase is an integral part of periodontal therapy. However, it is not known how much the length and strictness of this phase per se can reduce the periodontal pocket depths of a patient. Principal Findings: The present study show that a 3month, strict oral hygiene phase can reduce periodontal pocket depth extensively. This has the Practical Implications that it may change a periodontal treatment plan from one including periodontal surgery and/or antibiotics to one of more conservative therapy.
Oral hygiene phase revisited. How different study designs have affected results in intervention s... more Oral hygiene phase revisited. How different study designs have affected results in intervention studies.
The Nyvad classification is a visual-tactile caries classification system devised to enable the d... more The Nyvad classification is a visual-tactile caries classification system devised to enable the detection of the activity and severity of caries lesions with special focus on low-caries populations. The criteria behind the classification reflect the entire continuum of caries, ranging from clinically sound surfaces through noncavitated and microcavitated caries lesions in enamel, to frank cavitation into the dentin. Lesion activity at each severity stage is discriminated by differences in surface topography and lesion texture. The reliability of the Nyvad criteria is high to excellent when used by trained examiners in the primary and permanent dentitions. The Nyvad criteria have construct validity for lesion activity assessments because of their ability to reflect the well-known caries-controlling effect of fluoride. Predictive validity was demonstrated by showing that active noncavitated lesions are at higher risk of progressing to a cavity or filled state than do inactive noncavit...
It is with great interest that we have read the ''Analysis and Evaluation'' published by Faveri e... more It is with great interest that we have read the ''Analysis and Evaluation'' published by Faveri et al 1 in the Journal of Evidence-Based Dental Practice that concerns our recently published clinical trial. 2 We are indeed pleased to note that the reviewers of our publication find that our study ''could be classified as presenting 'low risk of bias', since it complied with the seven aspects of this [as outlined in the CONSORT statement, 3 our insert] quality analysis, which are sample size calculation, randomization and allocation concealment, inclusion and exclusion criteria, completeness of follow-up appointments, experimental groups comparable at baseline, presence of masking, and appropriate analysis''. The reviewers also point out ''the number of subjects evaluated (180) and a followup of 1 year'' as strengths of our study. Notwithstanding, the reviewers grade our study as being of Level 2 evidence: Limited-quality, patient oriented evidence. When consulting the Journal of Evidence-Based Dental Practice guideline for grading 4 we learn that this means our trial is a ''Lower quality clinical trial.'' Wondering how the above positive notes on the quality of our trial could be converted to a verdict of ''Lower quality clinical trial'' we have scrutinized the analysis by Faveri et al 1 for the causes of the apparent demise of our trial. Faveri et al 1 hold against us that we have used fullmouth outcomes, as they state ''full-mouth outcomes are not ideal to compare different therapies because the interpretation of these results is rather subjective and may mask the main effects of therapies''. We fail to understand why full-mouth outcomes would 1 result in subjective interpretations, while the alternative-presumably partial mouth or subset-based outcomes-would not. As regards the claim of masking the ''main effects of therapies'', it is true that CAL (or PD) can only improve where they were initially reduced (i.e., a baseline CAL > 0 mm; or baseline PD > 3-4 mm). Many investigators therefore prefer to base their outcome assessments only on sites with ''initially deep periodontal pockets,'' as these will show greater changes as a result of treatment and thereby increase the likelihood of greater between-group differences, as is proposed by Faveri et al. 1
The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP), wi... more The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP), with or without adjunctive metronidazole, when treating chronic, destructive periodontitis and the long-term association between clinical and microbiological outcomes after such strategies remains equivocal. To examine the relationship between clinical and microbiological outcomes of four different treatment strategies for chronic, destructive periodontitis among patients who maintain excellent oral hygiene and low gingival bleeding scores. 184 periodontitis patients capable of maintaining a high standard of oral hygiene were randomly allocated to one of four treatment groups 1) FDIS+metronidazole, 2) FDIS+placebo, 3) SRP+metronidazole, 4) SRP+placebo. Recordings of plaque, bleeding on probing, probing pocket depth and clinical attachment level were carried out in four sites per tooth at baseline, 3 and 12 months after treatment. Prior to treatment, pooled subgingival samples were obtained...
The reproducibility and reliability of quantitative microbiological assessments using the DNA-DNA... more The reproducibility and reliability of quantitative microbiological assessments using the DNA-DNA hybridization "checkerboard method" (CKB) were assessed. The data originated from 180 chronic periodontitis patients, who were enrolled in a clinical trial and sampled at baseline, and 3 and 12m post-therapy. The samples were divided into two portions allowing evaluation of reproducibility. In total, 531 samples were analyzed in a first run, using standard bacterial preparations of cells and 513 samples were accessible for analysis in the second, using standards based on purified DNA from the species. The microbial probe panel consisted of periodontitis marker bacteria as well as non-oral microorganisms. Three different ways of quantifying and presenting data; the visual scoring method, VSM, the standard curve method, SCM, and the percent method, PM, were compared. The second set of analyses based on the use of standard preparations of pure DNA was shown to be more consistent ...
The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP) in ... more The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP) in the treatment of chronic, destructive periodontitis remains equivocal and it is not known whether the use of adjunctive antibiotics may enhance the effect of FDIS. Therefore, the aim of this study was to evaluate the effect of conventional SRP completed over 21 days or 1-day FDIS, with or without systemically delivered adjunctive metronidazole (MET) on the presence of P. gingivalis and T. forsythia after 3 and 12 months. One hundred and eighty-four patients with moderate-to-severe periodontitis were randomly allocated to one of four treatment groups; (1) FDIS+MET; (2) FDIS+placebo; (3) SRP+MET; (4) SRP+placebo. Prior to treatment, pooled subgingival samples were obtained from the five deepest pockets. The same sites were sampled again 3 and 12 months after treatment. All samples were analyzed for P. gingivalis and T. forsythia by PCR, whereas A. actinomycetemcomitans and other bacteria w...
The prevalence of Actinobacillus actinomycetemcomitans isolates was examined in a rural populatio... more The prevalence of Actinobacillus actinomycetemcomitans isolates was examined in a rural population of southern Thailand. Sixty individuals aged 30-39 and 50-59 years were randomly selected from a group of 363 persons, living in four villages, who had been clinically examined previously. A subgingival plaque sample was taken with a curette from the mesial aspect of the two upper and lower first molars. Each sample was dispersed in 3.3 ml of VMGA III transport medium and spread onto Trypticase Soy Broth with Bacitracin and Vancomycin (TSBV)-agar plates on the same day. After incubation in 10% CO2 for 5 days the plates were examined for typical A. actinomycetemcomitans colonies which were tested for catalase activity. Each strain was further tested for biochemical characteristics, serotyped against serotype-specific antisera a-e and ribotyped after DNA digestion using the restriction endonucleases HindIII and EcoRI. For 53 (88%) of the 60 individuals, A. actinomycetemcomitans was present in at least one subgingival sample, which is considerably higher than the prevalence in Western European adults. In 11 individuals, two or three different strains were found. Serotypes a and c were the most prevalent, and serotype b was found only once among 46 tested isolates. Eleven ribotypes were found among the 46 strains. While the same ribotype could be found among individuals of the same village, no ribotype of A. actinomycetemcomitans was unique for individuals of any one village. The study demonstrated a high prevalence of A. actinomycetemcomitans among adults of the rural population of southern Thailand and indicates that this species is present as part of the resident oral flora in this population.
Two groups of elderly chinese were selected from a large epidemiological sample on the basis of a... more Two groups of elderly chinese were selected from a large epidemiological sample on the basis of a low ("best" group) or a high ("worst" group) number of sites with attachment loss levels > or = 6 mm and/or pocket depth > or = 4 mm and at least 16 teeth present. Six years later the patients were clinically reexamined and the subgingival microflora was assessed. This paper presents the clinical characteristics of destructive periodontal disease progression among the two subgroups. The "best" group lost an average of 1.8 teeth, contrasting the average loss of 5.3 teeth among the "worst" group. Virtually all teeth lost among the "worst" group had a baseline attachment loss level > or = 4 mm, in contrast to 48% among the "best" group. While dental caries could be identified as a cause of tooth loss in both groups, the excess tooth loss among the "worst" group seems attributable to periodontal destruction. The average of 1.21 mm attachment/site lost among the "best" group was not statistically significantly different from the 1.36 mm/site lost among the "worst" group during the 6 years. Individual mean losses of attachment ranged from a gain of 0.03 mm to a loss of 3.19 mm. An attachment loss > or = 2 mm at a site was highly positively associated with a high initial attachment loss level (> or = 4 mm) at that site among the "best" group, whereas a highly negative association was seen among the "worst" group.(ABSTRACT TRUNCATED AT 250 WORDS)
Smokers have frequently been reported to have more severe periodontitis, to respond less favorabl... more Smokers have frequently been reported to have more severe periodontitis, to respond less favorably to periodontal therapy, and to show elevated rate of recurrence compared with non-smokers. The aims of this study was to compare the results of baseline-adjusted and -unadjusted analyses when assessing the effect of smoking on change in periodontal status following therapy and to discuss the methodological issues involved. This is a secondary analysis of data from 180 periodontitis patients enrolled in a randomized controlled clinical intervention trial. Information on smoking habits was elicited from the participants before, and 12 months after, therapy. The clinical parameters analyzed were probing pocket depth and clinical attachment level, using both simple analysis of change (SAC) and analysis of covariance (ancova), adjusting for age, gender, and treatment group. The current smokers presented with more severe periodontitis at baseline than did former and never smokers. Results of the SAC indicated that the current smokers benefitted more from treatment than did former or never smokers, whereas the results of the baseline-adjusted ancova indicated no such differences. Both sets of results are likely to be biased with respect to valid conclusions regarding the 'causal' effect of smoking. Possible sources of bias are discussed.
This paper presents a method for the analysis of data originating from studies of destructive per... more This paper presents a method for the analysis of data originating from studies of destructive periodontal disease. The proposed method is an extension of the Mantel-Haenszel technique for the analysis of case-control studies and allows for expression of the site-specificity of destructive periodontal disease while maintaining the individual as the unit of analysis. Using data originating from a cross-sectional study of periodontal breakdown and oral hygiene parameters in a random sample of adult rural Kenyans, the proposed method is illustrated and the results compared with results obtained when two alternative analytical methods are used. The results demonstrate that the choice of analytical strategy may have profound implications for the conclusions to be drawn. Depending on the strategy chosen, one may draw conclusions which are qualitatively different and the present study indicates that the direction of these differences is not predictable.
In this study, the null hypothesis was tested that topical application of standard buffer solutio... more In this study, the null hypothesis was tested that topical application of standard buffer solutions, pH 7.00 and pH 4.01, to 4-day-old plaque deposits accumulated in situ causes the plaque to attain the pH values of the buffer solutions applied. Following a 4-day abstention from all oral hygiene procedures, the plaque pH of four interdental sites in each of 5 volunteers was measured at resting state and following topical applications of buffers pH 7 and pH 4. Later the same day plaque pH was measured following rinses with the buffers. Topical application of buffer pH 7 caused a plaque pH increased from a mean value of 6.40 to 6.59 within 30 s, while buffer pH 4 caused plaque pH to drop to a mean value of 5.11. Rinsing with buffers caused plaque pH to increase to 6.50 (buffer pH 7) and to drop to 4.92 (buffer pH 4). Statistical analysis of the results led to rejection of the null hypothesis. The results thus indicated that the validity of the in situ approach of calibration of plaque-covered indwelling electrodes may be questioned.
ABSTRACT Objectives: To describe the subgingival microbial profiles of selected putative periodon... more ABSTRACT Objectives: To describe the subgingival microbial profiles of selected putative periodontal pathogens and investigate their role as diagnostic markers for destructive periodontal diseases in a periodontally untreated and isolated population from Brazil. Materials and Methods: The target population consisted of all subjects aged ≥ 12 years, identified by a census. A full-mouth clinical examination was conducted and pooled subgingival plaque samples were obtained from four sites per subject. PCR analyses were performed to identify the following microorganisms: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia and Campylobacter rectus. Results: Among the 214 subjects (81% response rate) clinically examined, 170 of the 195 dentate provided subgingival plaque samples. Two main specific subgingival microbial profiles were identified: Absence of all microorganisms but Campylobacter rectus, or; co-occurrence of Tannerella forsythia and Porphyromonas gingivalis. Presence of selected periodontal microorganisms did not provide superior accuracy when added to traditional clinical markers. The best misclassification % for the diagnosis of at least one site with CAL ≥ 5 mm was 13.5 % for microbial + clinical markers and 16.5 % for clinical markers only (p = 0.292). Similarly, the misclassification % for the diagnosis of at least one site with CAL ≥ 7 mm was 7.6 % for microbial + clinical markers and 9.4 % for clinical markers only (p = 0.421). Conclusions: Specific microbial profiles could be identified in this isolated population, but did not provide significant superior diagnostic accuracy when added to traditional clinical markers. Funding: FAPESP grant numbers 09/50555-3 and 08/55404-0
This study describes the histopathological features and the distribution of oral epithelial Lange... more This study describes the histopathological features and the distribution of oral epithelial Langerhans cells in 19 gingival biopsies originating from an adult Tanzanian population characterized by very poor oral hygiene and severe gingiva! inflammation. Light-microscopically, all biopsies contained often large inflammatory connective tissue infiltrates, 6 of which predominantly contained plasma cells while the rest were dominated by lymphocytes. Seven specimens contained ed peculiar accumulations of round lymphoid and dendritic cells in the lower cell layers of the oral epithelium. These phenomena have not previously been demonstrated in human gingiva and deserve further attention in studies on the pathogenesis of periodontal diseases. Immuno-histochemical staining with 0KT6, OKT4 and OKT8 antibodies showed markedly increased numbers of OKT6-positive cells in 7 specimens and clusters of 0KT4-and OKT8-positive cells in the oral epithelium of 4 specimens. High numbers of OKT6-positive cells were not related to the presence of intra-epithelial, non-keratinocyte infiltrates or large connective tissue infiltrates. The variable numbers of oral epithelial Langerhans cells may therefore result from different bacterial antigens elucidating different responses or, alternatively, reflect different responses to similar plaque antigens penetrating the surface of the oral epithelium.
Scientific Rationale for Study: The oral hygiene phase is an integral part of periodontal therapy... more Scientific Rationale for Study: The oral hygiene phase is an integral part of periodontal therapy. However, it is not known how much the length and strictness of this phase per se can reduce the periodontal pocket depths of a patient. Principal Findings: The present study show that a 3month, strict oral hygiene phase can reduce periodontal pocket depth extensively. This has the Practical Implications that it may change a periodontal treatment plan from one including periodontal surgery and/or antibiotics to one of more conservative therapy.
Oral hygiene phase revisited. How different study designs have affected results in intervention s... more Oral hygiene phase revisited. How different study designs have affected results in intervention studies.
The Nyvad classification is a visual-tactile caries classification system devised to enable the d... more The Nyvad classification is a visual-tactile caries classification system devised to enable the detection of the activity and severity of caries lesions with special focus on low-caries populations. The criteria behind the classification reflect the entire continuum of caries, ranging from clinically sound surfaces through noncavitated and microcavitated caries lesions in enamel, to frank cavitation into the dentin. Lesion activity at each severity stage is discriminated by differences in surface topography and lesion texture. The reliability of the Nyvad criteria is high to excellent when used by trained examiners in the primary and permanent dentitions. The Nyvad criteria have construct validity for lesion activity assessments because of their ability to reflect the well-known caries-controlling effect of fluoride. Predictive validity was demonstrated by showing that active noncavitated lesions are at higher risk of progressing to a cavity or filled state than do inactive noncavit...
It is with great interest that we have read the ''Analysis and Evaluation'' published by Faveri e... more It is with great interest that we have read the ''Analysis and Evaluation'' published by Faveri et al 1 in the Journal of Evidence-Based Dental Practice that concerns our recently published clinical trial. 2 We are indeed pleased to note that the reviewers of our publication find that our study ''could be classified as presenting 'low risk of bias', since it complied with the seven aspects of this [as outlined in the CONSORT statement, 3 our insert] quality analysis, which are sample size calculation, randomization and allocation concealment, inclusion and exclusion criteria, completeness of follow-up appointments, experimental groups comparable at baseline, presence of masking, and appropriate analysis''. The reviewers also point out ''the number of subjects evaluated (180) and a followup of 1 year'' as strengths of our study. Notwithstanding, the reviewers grade our study as being of Level 2 evidence: Limited-quality, patient oriented evidence. When consulting the Journal of Evidence-Based Dental Practice guideline for grading 4 we learn that this means our trial is a ''Lower quality clinical trial.'' Wondering how the above positive notes on the quality of our trial could be converted to a verdict of ''Lower quality clinical trial'' we have scrutinized the analysis by Faveri et al 1 for the causes of the apparent demise of our trial. Faveri et al 1 hold against us that we have used fullmouth outcomes, as they state ''full-mouth outcomes are not ideal to compare different therapies because the interpretation of these results is rather subjective and may mask the main effects of therapies''. We fail to understand why full-mouth outcomes would 1 result in subjective interpretations, while the alternative-presumably partial mouth or subset-based outcomes-would not. As regards the claim of masking the ''main effects of therapies'', it is true that CAL (or PD) can only improve where they were initially reduced (i.e., a baseline CAL > 0 mm; or baseline PD > 3-4 mm). Many investigators therefore prefer to base their outcome assessments only on sites with ''initially deep periodontal pockets,'' as these will show greater changes as a result of treatment and thereby increase the likelihood of greater between-group differences, as is proposed by Faveri et al. 1
The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP), wi... more The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP), with or without adjunctive metronidazole, when treating chronic, destructive periodontitis and the long-term association between clinical and microbiological outcomes after such strategies remains equivocal. To examine the relationship between clinical and microbiological outcomes of four different treatment strategies for chronic, destructive periodontitis among patients who maintain excellent oral hygiene and low gingival bleeding scores. 184 periodontitis patients capable of maintaining a high standard of oral hygiene were randomly allocated to one of four treatment groups 1) FDIS+metronidazole, 2) FDIS+placebo, 3) SRP+metronidazole, 4) SRP+placebo. Recordings of plaque, bleeding on probing, probing pocket depth and clinical attachment level were carried out in four sites per tooth at baseline, 3 and 12 months after treatment. Prior to treatment, pooled subgingival samples were obtained...
The reproducibility and reliability of quantitative microbiological assessments using the DNA-DNA... more The reproducibility and reliability of quantitative microbiological assessments using the DNA-DNA hybridization "checkerboard method" (CKB) were assessed. The data originated from 180 chronic periodontitis patients, who were enrolled in a clinical trial and sampled at baseline, and 3 and 12m post-therapy. The samples were divided into two portions allowing evaluation of reproducibility. In total, 531 samples were analyzed in a first run, using standard bacterial preparations of cells and 513 samples were accessible for analysis in the second, using standards based on purified DNA from the species. The microbial probe panel consisted of periodontitis marker bacteria as well as non-oral microorganisms. Three different ways of quantifying and presenting data; the visual scoring method, VSM, the standard curve method, SCM, and the percent method, PM, were compared. The second set of analyses based on the use of standard preparations of pure DNA was shown to be more consistent ...
The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP) in ... more The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP) in the treatment of chronic, destructive periodontitis remains equivocal and it is not known whether the use of adjunctive antibiotics may enhance the effect of FDIS. Therefore, the aim of this study was to evaluate the effect of conventional SRP completed over 21 days or 1-day FDIS, with or without systemically delivered adjunctive metronidazole (MET) on the presence of P. gingivalis and T. forsythia after 3 and 12 months. One hundred and eighty-four patients with moderate-to-severe periodontitis were randomly allocated to one of four treatment groups; (1) FDIS+MET; (2) FDIS+placebo; (3) SRP+MET; (4) SRP+placebo. Prior to treatment, pooled subgingival samples were obtained from the five deepest pockets. The same sites were sampled again 3 and 12 months after treatment. All samples were analyzed for P. gingivalis and T. forsythia by PCR, whereas A. actinomycetemcomitans and other bacteria w...
The prevalence of Actinobacillus actinomycetemcomitans isolates was examined in a rural populatio... more The prevalence of Actinobacillus actinomycetemcomitans isolates was examined in a rural population of southern Thailand. Sixty individuals aged 30-39 and 50-59 years were randomly selected from a group of 363 persons, living in four villages, who had been clinically examined previously. A subgingival plaque sample was taken with a curette from the mesial aspect of the two upper and lower first molars. Each sample was dispersed in 3.3 ml of VMGA III transport medium and spread onto Trypticase Soy Broth with Bacitracin and Vancomycin (TSBV)-agar plates on the same day. After incubation in 10% CO2 for 5 days the plates were examined for typical A. actinomycetemcomitans colonies which were tested for catalase activity. Each strain was further tested for biochemical characteristics, serotyped against serotype-specific antisera a-e and ribotyped after DNA digestion using the restriction endonucleases HindIII and EcoRI. For 53 (88%) of the 60 individuals, A. actinomycetemcomitans was present in at least one subgingival sample, which is considerably higher than the prevalence in Western European adults. In 11 individuals, two or three different strains were found. Serotypes a and c were the most prevalent, and serotype b was found only once among 46 tested isolates. Eleven ribotypes were found among the 46 strains. While the same ribotype could be found among individuals of the same village, no ribotype of A. actinomycetemcomitans was unique for individuals of any one village. The study demonstrated a high prevalence of A. actinomycetemcomitans among adults of the rural population of southern Thailand and indicates that this species is present as part of the resident oral flora in this population.
Two groups of elderly chinese were selected from a large epidemiological sample on the basis of a... more Two groups of elderly chinese were selected from a large epidemiological sample on the basis of a low ("best" group) or a high ("worst" group) number of sites with attachment loss levels > or = 6 mm and/or pocket depth > or = 4 mm and at least 16 teeth present. Six years later the patients were clinically reexamined and the subgingival microflora was assessed. This paper presents the clinical characteristics of destructive periodontal disease progression among the two subgroups. The "best" group lost an average of 1.8 teeth, contrasting the average loss of 5.3 teeth among the "worst" group. Virtually all teeth lost among the "worst" group had a baseline attachment loss level > or = 4 mm, in contrast to 48% among the "best" group. While dental caries could be identified as a cause of tooth loss in both groups, the excess tooth loss among the "worst" group seems attributable to periodontal destruction. The average of 1.21 mm attachment/site lost among the "best" group was not statistically significantly different from the 1.36 mm/site lost among the "worst" group during the 6 years. Individual mean losses of attachment ranged from a gain of 0.03 mm to a loss of 3.19 mm. An attachment loss > or = 2 mm at a site was highly positively associated with a high initial attachment loss level (> or = 4 mm) at that site among the "best" group, whereas a highly negative association was seen among the "worst" group.(ABSTRACT TRUNCATED AT 250 WORDS)
Smokers have frequently been reported to have more severe periodontitis, to respond less favorabl... more Smokers have frequently been reported to have more severe periodontitis, to respond less favorably to periodontal therapy, and to show elevated rate of recurrence compared with non-smokers. The aims of this study was to compare the results of baseline-adjusted and -unadjusted analyses when assessing the effect of smoking on change in periodontal status following therapy and to discuss the methodological issues involved. This is a secondary analysis of data from 180 periodontitis patients enrolled in a randomized controlled clinical intervention trial. Information on smoking habits was elicited from the participants before, and 12 months after, therapy. The clinical parameters analyzed were probing pocket depth and clinical attachment level, using both simple analysis of change (SAC) and analysis of covariance (ancova), adjusting for age, gender, and treatment group. The current smokers presented with more severe periodontitis at baseline than did former and never smokers. Results of the SAC indicated that the current smokers benefitted more from treatment than did former or never smokers, whereas the results of the baseline-adjusted ancova indicated no such differences. Both sets of results are likely to be biased with respect to valid conclusions regarding the 'causal' effect of smoking. Possible sources of bias are discussed.
This paper presents a method for the analysis of data originating from studies of destructive per... more This paper presents a method for the analysis of data originating from studies of destructive periodontal disease. The proposed method is an extension of the Mantel-Haenszel technique for the analysis of case-control studies and allows for expression of the site-specificity of destructive periodontal disease while maintaining the individual as the unit of analysis. Using data originating from a cross-sectional study of periodontal breakdown and oral hygiene parameters in a random sample of adult rural Kenyans, the proposed method is illustrated and the results compared with results obtained when two alternative analytical methods are used. The results demonstrate that the choice of analytical strategy may have profound implications for the conclusions to be drawn. Depending on the strategy chosen, one may draw conclusions which are qualitatively different and the present study indicates that the direction of these differences is not predictable.
In this study, the null hypothesis was tested that topical application of standard buffer solutio... more In this study, the null hypothesis was tested that topical application of standard buffer solutions, pH 7.00 and pH 4.01, to 4-day-old plaque deposits accumulated in situ causes the plaque to attain the pH values of the buffer solutions applied. Following a 4-day abstention from all oral hygiene procedures, the plaque pH of four interdental sites in each of 5 volunteers was measured at resting state and following topical applications of buffers pH 7 and pH 4. Later the same day plaque pH was measured following rinses with the buffers. Topical application of buffer pH 7 caused a plaque pH increased from a mean value of 6.40 to 6.59 within 30 s, while buffer pH 4 caused plaque pH to drop to a mean value of 5.11. Rinsing with buffers caused plaque pH to increase to 6.50 (buffer pH 7) and to drop to 4.92 (buffer pH 4). Statistical analysis of the results led to rejection of the null hypothesis. The results thus indicated that the validity of the in situ approach of calibration of plaque-covered indwelling electrodes may be questioned.
ABSTRACT Objectives: To describe the subgingival microbial profiles of selected putative periodon... more ABSTRACT Objectives: To describe the subgingival microbial profiles of selected putative periodontal pathogens and investigate their role as diagnostic markers for destructive periodontal diseases in a periodontally untreated and isolated population from Brazil. Materials and Methods: The target population consisted of all subjects aged ≥ 12 years, identified by a census. A full-mouth clinical examination was conducted and pooled subgingival plaque samples were obtained from four sites per subject. PCR analyses were performed to identify the following microorganisms: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia and Campylobacter rectus. Results: Among the 214 subjects (81% response rate) clinically examined, 170 of the 195 dentate provided subgingival plaque samples. Two main specific subgingival microbial profiles were identified: Absence of all microorganisms but Campylobacter rectus, or; co-occurrence of Tannerella forsythia and Porphyromonas gingivalis. Presence of selected periodontal microorganisms did not provide superior accuracy when added to traditional clinical markers. The best misclassification % for the diagnosis of at least one site with CAL ≥ 5 mm was 13.5 % for microbial + clinical markers and 16.5 % for clinical markers only (p = 0.292). Similarly, the misclassification % for the diagnosis of at least one site with CAL ≥ 7 mm was 7.6 % for microbial + clinical markers and 9.4 % for clinical markers only (p = 0.421). Conclusions: Specific microbial profiles could be identified in this isolated population, but did not provide significant superior diagnostic accuracy when added to traditional clinical markers. Funding: FAPESP grant numbers 09/50555-3 and 08/55404-0
This study describes the histopathological features and the distribution of oral epithelial Lange... more This study describes the histopathological features and the distribution of oral epithelial Langerhans cells in 19 gingival biopsies originating from an adult Tanzanian population characterized by very poor oral hygiene and severe gingiva! inflammation. Light-microscopically, all biopsies contained often large inflammatory connective tissue infiltrates, 6 of which predominantly contained plasma cells while the rest were dominated by lymphocytes. Seven specimens contained ed peculiar accumulations of round lymphoid and dendritic cells in the lower cell layers of the oral epithelium. These phenomena have not previously been demonstrated in human gingiva and deserve further attention in studies on the pathogenesis of periodontal diseases. Immuno-histochemical staining with 0KT6, OKT4 and OKT8 antibodies showed markedly increased numbers of OKT6-positive cells in 7 specimens and clusters of 0KT4-and OKT8-positive cells in the oral epithelium of 4 specimens. High numbers of OKT6-positive cells were not related to the presence of intra-epithelial, non-keratinocyte infiltrates or large connective tissue infiltrates. The variable numbers of oral epithelial Langerhans cells may therefore result from different bacterial antigens elucidating different responses or, alternatively, reflect different responses to similar plaque antigens penetrating the surface of the oral epithelium.
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Papers by Vibeke Baelum