Recovery of A. actinomycetemcomitans from teeth, tongue, and saliva

The oral microbiome of children in health and disease-a literature review

The oral microbiome is a complex community of microorganisms residing in the oral cavity interacting with each other and with the host in a state of equilibrium. Disruptions in this balance can result in both oral and systemic conditions. Historically, studying the oral microbiome faced limitations due to culture-dependent techniques that could not capture the complexity and diversity of the microbial community. The emergence of advanced genomic technologies and the ease of sample collection from the oral cavity has revolutionized the understanding of the oral microbiome, providing valuable insights into the bacterial community in both health and disease. This review explores the oral microbiome in children, discussing its formation and dynamics in both states of health and disease, its role in various conditions such as dental caries, periodontal disease, oral cancer, cleft lip and palate, and explores its connection to several systemic consequences.

Adaptation by Ancient Horizontal Acquisition of Butyrate Metabolism Genes in Aggregatibacter actinomycetemcomitans

There has been considerable interest in the impact of short-chain fatty acids (SCFAs) on inflammatory effects related to the microbiome. Here, we present evidence that SCFAs may also be important in disease by providing an energy source or disease-associated cue for colonizing pathogens.

Like the bacterial residents of the human gut, it is likely that many of the species in the human oral microbiota have evolved to better occupy and persist in their niche. Aggregatibacter actinomycetemcomitans (Aa) is both a common colonizer of the oral cavity and has been implicated in the pathogenesis of periodontal disease. Here, we present a whole-genome phylogenetic analysis of Aa isolates from humans and nonhuman primates that revealed an ancient origin for this species and a long history of association with the Catarrhini, the lineage that includes Old World monkeys (OWM) and humans. Further genomic analysis showed a strong association with the presence of a short-chain fatty acid (SCFA) catabolism locus (atoRDAEB) in many human isolates that was absent in almost all nonhuman OWM isolates. We show that this locus was likely acquired through horizontal gene transfer. When grown under conditions that are similar to those at the subgingival site of periodontitis (anaerobic, SCFA replete), Aa strains with atoRDAEB formed robust biofilms and showed upregulation of genes involved in virulence, colonization, and immune evasion. Both an isogenic deletion mutant and nonhuman primate isolates lacking the ato locus failed to grow in a robust biofilm under these conditions, but grew well under the carbohydrate-rich conditions similar to those found above the gumline. We propose that the acquisition of the ato locus was a key evolutionary step allowing Aa to utilize SCFAs, adapt, and modulate subgingival disease.

Intraindividual Variation and Personal Specificity of Salivary Microbiota

Salivary microbiota is a typical habitat of the human microbiome. This study intended to use salivary microbiota as a model aiming to systematically address the influence of collection methods and temporal dynamics on the human microbiota compared to personal specificity. We carried out a supervised short-term longitudinal study to evaluate the influence of the change of collection methods and sampling time point on salivary microbiota in 10 systemically and orally healthy individuals with certain confounding factors (sex, oral and general health state, medication history, physical exercise, diet, and oral hygiene behavior) controlled before and during the sampling period. The microbial profiles were analyzed by 16S rDNA V3 to V4 hypervariable region amplicon sequencing. The taxonomic structure represented by the dominant species and the weighted UniFrac distance algorithm were used to demonstrate the individual specificity and the intraindividual variation introduced by the change of collection method and sampling time point. The findings suggested individual specificity existed in salivary microbiota from individuals with similar oral and general health status. The intraindividual variation brought by the change of collection method or sampling time point might introduce remarkable perturbation with the personal specificity. Insights into the intraindividual variation and personal specificity of salivary microbiota will enhance our understanding in salivary microbiota-related research. We recommend keeping collection conditions consistent within a study to avoid interference brought by the sampling. The strategy of repeated sampling at multiple time points as representative samples, as well as thorough interpretation of the complex relationships and causality between microbiome composition and disease without the interference of temporal dynamics, is optimal for research exploring the relationship between the salivary microbiome and disease.

Real-time polymerase chain reaction quantification of the salivary levels of cariogenic bacteria in patients with orthodontic fixed appliances

Aim

The aim was to investigate the salivary detection frequencies and quantities of caries‐associated bacteria from patients with orthodontic brackets.

Methods

Patients wearing orthodontic brackets (n = 40, mean age = 26 years) and healthy controls without brackets (n = 40, mean age = 17 years) were enrolled in the study. Saliva samples from each patient was collected. After DNA purification, target species comprising streptococci and a Lactobacillus species were detected and quantified from the samples using polymerase chain reaction (PCR) and real‐time quantitative PCR.

Results

Detection frequencies did not differ between the orthodontic patients and the control subjects for any target species except for Streptococcus sobrinus, which showed significantly lower detection rates in orthodontic patients (p < .05). Lactobacillus casei and Streptococcus gordonii were found at the highest detection frequencies with both species being detected in 38 (95%) of the saliva samples of orthodontic patients. Similarly, L. casei and Streptococcus salivarius were the species with highest detection frequencies (35, 87.5%) in the control subjects. Real‐time PCR revealed that Streptococcus mutans and S. salivarius quantities were significantly higher in orthodontic patients than in the control subjects (p < .05).

Conclusions

Application of orthodontic brackets for 12 months leads to increased salivary levels of cariogenic bacteria and may serve as a potential risk factor for caries initiation.

Comparison of Bacterial Contamination and Antibacterial Efficacy in Bristles of Charcoal Toothbrushes versus Noncharcoal Toothbrushes: A Microbiological Study

Background:

Charcoal toothbrushes have been marketed widely claiming lesser bacterial contamination owing to the presence of activated charcoal.

Aim and Objective:

The aim of this study was to evaluate the bacterial contamination and antimicrobial efficacy of charcoal bristles compared to noncharcoal bristles in used toothbrushes.

Materials and Methods:

A total of 50 patients met inclusion criteria which were given standard brushing instructions on the use of a charcoal toothbrush and were asked to return the used brushes after 1 week of usage. After a washout period of 1-week, the participants were then provided with noncharcoal toothbrush and given similar brushing instructions to both groups and were instructed to return the brush after another week of usage. Bristles of the used toothbrushes were sectioned and placed in a 5 ml of saline, and 0.1 ml was inoculated on blood agar plates, which were then placed in a gas pack jar for anaerobic culture. Colony forming units (CFU) were measured after 48 h of incubation. To evaluate the antibacterial efficacy of charcoal bristles, the zone of inhibition was evaluated for charcoal versus noncharcoal after 24 h of incubation. Data collected were analyzed using a paired sample t-test.

Results:

The mean CFU count for noncharcoal bristles was almost double that of charcoal bristles. About 10 mm of the zone of inhibition was found around charcoal bristles as compared to 3 mm for noncharcoal bristles.

Conclusion:

This study shows the statistically significant difference in bacterial counts between bristle types and lower CFUs in the charcoal bristles compared with noncharcoal bristles, after 1 week of use. The zone of inhibition that was found around charcoal tooth bristles supported the antimicrobial properties of the charcoal toothbrush.

Nonsurgical and surgical treatment of periodontitis: how many options for one disease?

Treatment of periodontitis aims at preventing further disease progression with the intentions to reduce the risk of tooth loss, minimize symptoms and perception of the disease, possibly restore lost periodontal tissue and provide information on maintaining a healthy periodontium. Therapeutic intervention includes introduction of techniques to change behavior, such as: individually tailored oral-hygiene instructions; a smoking-cessation program; dietary adjustment; subgingival instrumentation to remove plaque and calculus; local and systemic pharmacotherapy; and various types of surgery. No single treatment option has shown superiority, and virtually all types of mechanical periodontal treatment benefit from adjunctive antimicrobial chemotherapy. Periodontal treatment, because of the chronic nature of periodontitis, is a lifelong commitment to intricate oral-hygiene techniques, which, when properly implemented, will minimize the risk of disease initiation and progression.

Aggregatibacter actinomycetemcomitans Growth in Biofilm versus Planktonic State: Differential Expression of Proteins

Aggregatibacter actinomycetemcomitans (Aa) is a pathogenic bacterium residing in the subgingival plaque biofilm strongly associated with the pathogenesis of periodontitis. The aim of this investigation was to study the protein differential expression of Aa when growing on biofilm compared with planktonic state using proteomic analysis by the 2D-DIGE system. Eighty-seven proteins were differentially expressed during biofilm growth (1.5-fold, p < 0.05), with 13 overexpressed and 37 down-expressed. Those repressed were mainly proteins involved in metabolism, biosynthesis, and transport. The overexpressed proteins were outer membrane proteins (OMPs) and highly immunogenic proteins such as YaeT (OMP), FtsZ, OMP39, OMP18/16, the chaperone GroEL, OMPA, adenylate kinase (Adk), and dihydrolipoamide acetyltransferase. The enrichment fractions of the OMPs from biofilm and planktonic states were obtained, and these proteins were analyzed by Western blotting with human serum from a periodontitis patient and one healthy control. These immunogenic proteins overexpressed in the biofilm may represent candidate virulence factors.

Effect of preparation method and storage period on the stability of saliva DNA

Saliva is an attractive source for oral microbial detection and quantification since sampling is non-invasive and rapid.

OBJECTIVES

To determine whether different saliva preparation methods or preservation time periods affect DNA stability.

METHODS

Saliva samples from 4 healthy adult volunteers were processed to obtain 3 different preparations: whole saliva, and after centrifugation pellet and supernatant. Purified DNA (MasterPure™) from each sample was divided into 4 aliquots, one for immediate analysis and 3 (stored at -80°C) for later analyses after 1 week and 2 and 6 months. DNA concentrations and qPCR based quantities of Porphyromonas gingivalis, Prevotella intermedia, Parvimonas micra, Fusobacterium nucleatum, Filifactor alocis and Streptococcus mutans were determined.

RESULTS

DNA concentration did not decrease (P>0.05) during the 6-month period in any sample. Mean (SE) DNA concentrations (ng/μl) in whole saliva were 152.2 (51.2) and 147.8 (50) at day 0 and 6 months, respectively. Similarly, the values for pellet were 134.9 (42.5) and 133.6 (42.9), and for supernatant, 11 (1.9) and 8.9 (2.3), the difference being significant (P<0.001) between supernatant and whole saliva or pellet. The quantities of most bacterial species found at day 0 remained stable over the 6-month period in all saliva preparations. In supernatant, species quantities were lower (P<0.05) than in whole saliva or pellet.

CONCLUSIONS

DNA concentrations were comparable between whole saliva and pellet, suggesting that either of them can be used for DNA-based analyses. Our results also demonstrated that DNA extracted from saliva can be preserved at -80°C for at least 6 months without decrease in DNA concentration.

Comparative analysis of bacterial profiles in unstimulated and stimulated saliva samples

Background and objective

The microbial profiles of stimulated saliva samples have been shown to differentiate between patients with periodontitis, patients with dental caries, and orally healthy individuals. Saliva was stimulated to allow for easy and rapid collection; however, microbial composition may not reflect the more natural, unstimulated state. The purpose of this study was to validate whether stimulated saliva is an adequate surrogate for unstimulated saliva in determining salivary microbiomes.

Design

Unstimulated (n=20) and stimulated (n=20) saliva samples were collected from 20 orally and systemically healthy, non-smoking participants. Salivary bacterial profiles were analyzed by means of the Human Oral Microbe Identification using Next Generation Sequencing (HOMINGS), and statistical analysis was performed using Mann–Whitney test with Benjamini–Hochberg's correction for multiple comparison, cluster analysis, principal component analysis, and correspondence analysis.

Results

From a total of 40 saliva samples, 496 probe targets were identified with a mean number of targets per sample of 203 (range: 146–303), and a mean number of probe targets of 206 and 200 in unstimulated and stimulated saliva samples, respectively (p=0.62). Based on all statistical methods used for this study, the microbial profiles of unstimulated and stimulated saliva samples collected from the same person were not statistically significantly different.

Conclusions

Analysis of bacterial salivary profiles in unstimulated and stimulated saliva samples collected from the same individual showed comparable results. Thus, the results verify that stimulated saliva is an adequate surrogate of unstimulated saliva for microbiome-related studies.

Salivary carriage of periodontal pathogens in generalized aggressive periodontitis families

BACKGROUND

Generalized aggressive periodontitis (GAP) is a multifactorial disease that shows a specific microbial profile and a familial aggregation.

AIM

This study evaluated the salivary microbial profile of families with a history of GAP and compared them with healthy families.

DESIGN

Fifteen families with parents presenting periodontal health and 15 with parents with a history of GAP were selected. Each family had a child aged 6-12 years. Stimulated saliva was collected from all subjects, and Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), and Aggregatibacter actinomycetemcomitans (Aa) amounts were determined.

RESULTS

Children of GAP families showed higher detection of Aa (90%) than children of healthy families (45%) (P < 0.05). Parents with GAP showed a Pg salivary concentration statistically higher than that of healthy parents (P < 0.05).Children of GAP families, however, exhibited similar Pg concentration than healthy children (P > 0.05). Tf amounts did not differ either in parents or in children (P > 0.05) The infection risk calculation indicates that children who have one parent who is positive for Aa have 16.3 times (95% CI 3.1-87.2) more risk of being infected with Aa (P < 0.05) than children from an Aa-negative family.

CONCLUSION

It may be concluded that children of parents with aggressive periodontitis have higher levels and higher risk of Aa infection.

Evaluation of the effect of one stage versus two stage full mouth disinfection on C-reactive protein and leucocyte count in patients with chronic periodontitis

Background:

Conventional non-surgical periodontal therapy is carried out in quadrant basis with 1-2 week interval. This time lag may result in re-infection of instrumented pocket and may impair healing. Therefore, a new approach to full-mouth non-surgical therapy to be completed within two consecutive days with full-mouth disinfection has been suggested. In periodontitis, leukocyte counts and levels of C-reactive protein (CRP) are likely to be slightly elevated, indicating the presence of infection or inflammation. The aim of this study is to compare the efficacy of one stage and two stage non-surgical therapy on clinical parameters along with CRP levels and total white blood cell (TWBC) count.

Materials and Methods:

A total of 20 patients were selected and were divided into two groups. Group 1 received one stage full mouth dis-infection and Group 2 received two stages FMD. Plaque index, sulcus bleeding index, probing depth, clinical attachment loss, serum CRP and TWBC count were evaluated for both the groups at baseline and at 1 month post-treatment.

Results:

The results were analyzed using the Student t-test. Both treatment modalities lead to a significant improvement of the clinical and hematological parameters; however comparison between the two groups showed no significant difference after 1 month.

Conclusion:

The therapeutic intervention may have a systemic effect on blood count in periodontitis patients. Though one stage FMD had limited benefits over two stages FMD, the therapy can be accomplished in a shorter duration.

Genomic Stability of Aggregatibacter actinomycetemcomitans during Persistent Oral Infection in Human

The genome of periodontal pathogen Aggregatibacter actinomycetemcomitans exhibits substantial variations in gene content among unrelated strains primarily due to the presence or absence of genomic islands. This study examined the genomic stability of A. actinomycetemcomitans during its persistent infection in the same host. Four pairs of A. actinomycetemcomitans strains, each pair isolated from an individual over time (0–10 years), were examined for their gains/losses of genes by whole genome sequencing, comparative genomic hybridization by microarray and PCR analysis. Possible effects due to genomic changes were further assessed by comparative transcriptome analysis using microarrays. The results showed that each pair of strains was clonally identical based on phylogenetic analysis of 150 core genes. A novel 24.1-Kb plasmid found in strain S23A was apparently lost in the sibling strain I23C. A 353-bp inversion affecting two essential genes of the serotype-specific gene cluster was found in the serotype antigen-nonexpressing strain I23C, while the same gene cluster was intact in the serotype-expressing sibling strain S23A. A 2,293-bp deletion affecting a gene encoding oxaloacetate decarboxylase and its neighbor region was found in strain SCC2302 but not in the sibling strain AAS4a. However, no evidence of gains or losses of genomic islands was found in the paired strains. Transcriptome profiles showed little or no difference in the paired strains. In conclusion, the genome of A. actinomycetemcomitans appears to be relatively stable during short-term infection. Several types of genomic changes were observed in the paired strains of A. actinomycetemcomitans recovered from the same subjects, including a mutation in serotype-specific gene cluster that may allow the bacteria to evade host immune response.

Saliva: A diagnostic biomarker of periodontal diseases

Early detection of disease plays a crucial role in successful therapy. Early diagnosis and management reduces the severity and possible complications of the disease process. To overcome this challenge, medical researchers are devoted to finding molecular disease biomarkers that reveal a hidden lethal threat before the disease becomes complicated. Saliva, an important physiologic fluid, containing a highly complex mixture of substances, is rapidly gaining popularity as a diagnostic tool. Periodontal disease is a chronic disease of the oral cavity comprising a group of inflammatory conditions affecting the supporting structures of the dentition. In the field of periodontology, traditional clinical criteria are often insufficient for determining sites of active disease, for monitoring the response to therapy, or for measuring the degree of susceptibility to future disease progression. Saliva, as a mirror of oral and systemic health, is a valuable source for clinically relevant information because it contains biomarkers specific for the unique physiologic aspects of periodontal diseases. This review highlights the various potentials of saliva as a diagnostic biomarker for periodontal diseases.

A review of C-reactive protein: A diagnostic indicator in periodontal medicine

Periodontitis is a local inflammatory process mediating the destruction of periodontal tissues, triggered by bacterial insult. Recent evidence suggests the presence of chronic inflammatory periodontal disease may significantly affect systemic health conditions such as coronary heart disease, stroke, or adverse pregnancy outcome. C-reactive protein (CRP) is an acute phase protein which reflects a measure of the acute phase response. CRP is used as one of the markers of choice in monitoring the acute phase response because it increases to a relatively high concentration compared to basal concentration. CRP has been shown to predict cardiovascular (CV) mortality in recent studies, and elevated CRP levels have been observed in middle-aged patients with periodontitis. Combination of chronic infections like periodontitis with elevated CRP is associated with higher chronic heart diseases. The recognition of the relationship between periodontal diseases and atherosclerotic events is relatively recent and mostly based on the inflammatory hypothesis of atherosclerosis. Periodontal disease is one of the risk factors for cardiovascular disease and possibly one of its causes. Hence, even associations of modest magnitude have a large impact. The cost to the society directly attributable to atherosclerotic sequelae is very large. Periodontitis is treatable; moreover, it is preventable. Experimental conformation of this shows that another widely prevalent and preventable contributor to the burden of cardiovascular disease would be added to the options available of the clinicians and public health practitioners for the control of the epidemic of cardiovascular disease.

Non-surgical management of periodontal disease

Non-surgical removal of plaque and calculus has been part of the initial phase of the management of patients with gingivitis and periodontitis for decades. It consists of patient motivation and oral hygiene instruction as well as mechanical removal of supra and subgingival plaque deposits. The purpose of this review was to assess recent changes. The article reports on changes in our understanding of plaque as a biofilm, developments in patient plaque control, chemical plaque control and scaling instruments. It also comments on full-mouth disinfection, the use of lasers and host modulation. Modern technology has made removal of microbial deposits by the patient and dental professionals more efficient. However, other advancements need to be used in conjunction with mechanical debridement at this time.

Salivary Genomics, Transcriptomics and Proteomics: The Emerging Concept of the Oral Ecosystem and their Use in the Early Diagnosis of Cancer and other Diseases

There is an increasingly growing interest world-wide for the genomics, transcriptomics and proteomics of saliva and the oral cavity, since they provide a non-invasive source of unprecedently rich genetic information. The complexity of oral systems biology goes much beyond the human genome, transcriptome and proteome revealed by oral mucosal cells, gingival crevicular fluid, and saliva, and includes the complexity of the oral microbiota, the symbiotic assembly of bacterial, fungal and other microbial flora in the oral cavity. In our review we summarize the recent information on oral genomics, transcriptomics and proteomics, of both human and microbial origin. We also give an introduction and practical advice on sample collection, handling and storage for analysis. Finally, we show the usefulness of salivary and oral genomics in early diagnosis of cancer, as well as in uncovering other systemic diseases, infections and oral disorders. We close the review by highlighting a number of possible exploratory pathways in this emerging, hot research field.

Population-based study of salivary carriage of periodontal pathogens in adults

Large, general population-based data on carriage rates of periodontal pathogens hardly exist in the current literature. The objectives of the present study were to examine the salivary detection of Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans, Campylobacter rectus, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Treponema denticola in a representative sample of the adult population living in southern Finland and to clarify which determinants are associated with the presence of these pathogens in saliva. 16S rRNA-based PCR methods with species-specific primers were employed to determine the presence of the six target bacteria in stimulated saliva samples, which were available from 1,294 subjects aged > or =30 years. The age group, gender, level of education, marital status, smoking history, number of teeth, and number of teeth with deepened pockets were included in the statistical analysis. In general, the carriage of periodontal pathogens was common, since at least one of the examined pathogens was found in 88.2% of the subjects. In descending order, the total detection rates were 56.9%, 38.2%, 35.4%, 31.3%, 20.0%, and 13.9% for T. forsythensis, T. denticola, P. gingivalis, C. rectus, A. actinomycetemcomitans, and P. intermedia, respectively. Age per se was strongly associated with the carriage of P. gingivalis (P = 0.000), and the level of education with that of T. denticola (P = 0.000). There was an association between the number of teeth with deepened pockets and carriage of P. gingivalis (P = 0.000), P. intermedia (P = 0.000), T. denticola (P = 0.000), and A. actinomycetemcomitans (P = 0.004). The data suggest that distinct species have a different carriage profile, depending on variables such as age, educational level, and periodontal status.

Comparison of subgingival bacterial sampling with oral lavage for detection and quantification of periodontal pathogens by real-time polymerase chain reaction

BACKGROUND

Saliva has been studied for the presence of subgingival pathogens in periodontitis patients. With the anaerobic culture technique, the discrepancy between salivary recovery and subgingival presence has been significant, which makes this approach not suitable for practical use in the microbial diagnosis of periodontitis patients. The real-time polymerase chain reaction (PCR) technique represents a very sensitive technique to detect and quantify bacterial pathogens. The aim of the study was to compare the presence and numbers of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythensis, Prevotella intermedia, and Micromonas micros in subgingival plaque and mouthwash samples by the anaerobic culture and real-time PCR techniques.

METHODS

Pooled subgingival plaque samples and 10-ml mouthwash samples were collected from 21 adult patients with periodontitis and analyzed by quantitative anaerobic culture and real-time PCR for A. actinomycetemcomitans, P. gingivalis, T. forsythensis, P. intermedia, and M. micros.

RESULTS

The detection frequency of A. actinomycetemcomitans, P. gingivalis, and T. forsythensis in subgingival plaque was identical by culture and real-time PCR and was higher for P. intermedia and M. micros by real-time PCR. The highest detection frequencies for the target bacteria were found in mouthwash samples by real-time PCR. The additional value of the real-time PCR to detect target bacteria was 38% for P. gingivalis, 73% for T. forsythensis, 77% for P. intermedia, and 71% for M. micros. The sensitivity to detect target species in mouthwash by real-time PCR was 100% for all test species except for P. intermedia (93.8%).

CONCLUSIONS

Rapid detection and quantification of periodontal pathogens in mouthwash samples are possible by real-time PCR. The procedure is significantly less time-consuming than subgingival sampling with paper points. This approach to detect major periodontal pathogens in mouthwash samples may simplify microbial diagnosis in periodontitis patients and may be used to monitor periodontal treatment.

Microbiota of the dorsum of the tongue after plaque accumulation: an experimental study in humans

BACKGROUND

The purpose of the present investigation was to determine the effect of the absence of tongue hygiene on the microbiota of the dorsum of the tongue.

METHODS

Ten volunteers (aged 19 to 22 years) entered the study at baseline and were instructed to abstain from tongue cleaning for 7 days, followed by a period of 3 days without any kind of oral hygiene. Subsequently, a period of 21 days of washout was employed, and this protocol was repeated three times. Microbiological samples were obtained from the dorsum of the tongue at baseline and at the end of the period of coating accumulation and analyzed using the checkerboard DNA-DNA hybridization technique.

RESULTS

The species found in highest mean counts at baseline and day 10 were Prevotella melaninogenica and Veillonella parvula. The mean bacterial total counts enhanced significantly during the study (from 17.1x10(6) to 33.7x10(6)). Proportions of red and blue complexes and levels of 18 species also increased after the period of coating accumulation, including several periodontal pathogens, such as Prevotella intermedia, Prevotella nigrescens, Streptococcus constellatus, Tannerella forsythensis, Porphyromonas gingivalis, Treponema denticola, and P. melaninogenica.

CONCLUSION

The tongue surface could be an important reservoir for periodontal pathogens and may play a role in the recolonization of tooth surfaces and in the etiology of oral halitosis.

The TadV protein of Actinobacillus actinomycetemcomitans is a novel aspartic acid prepilin peptidase required for maturation of the Flp1 pilin and TadE and TadF pseudopilins

The tad locus of Actinobacillus actinomycetemcomitans encodes genes for the biogenesis of Flp pili, which allow the bacterium to adhere tenaciously to surfaces and form strong biofilms. Although tad (tight adherence) loci are widespread among bacterial and archaeal species, very little is known about the functions of the individual components of the Tad secretion apparatus. Here we characterize the mechanism by which the pre-Flp1 prepilin is processed to the mature pilus subunit. We demonstrate that the tadV gene encodes a prepilin peptidase that is both necessary and sufficient for proteolytic maturation of Flp1. TadV was also found to be required for maturation of the TadE and TadF pilin-like proteins, which we term pseudopilins. Using site-directed mutagenesis, we show that processing of pre-Flp1, pre-TadE, and pre-TadF is required for biofilm formation. Mutation of a highly conserved glutamic acid residue at position +5 of Flp1, relative to the cleavage site, resulted in a processed pilin that was blocked in assembly. In contrast, identical mutations in TadE or TadF had no effect on biofilm formation, indicating that the mechanisms by which Flp1 pilin and the pseudopilins function are distinct. We also determined that two conserved aspartic acid residues in TadV are critical for function of the prepilin peptidase. Together, our results indicate that the A. actinomycetemcomitans TadV protein is a member of a novel subclass of nonmethylating aspartic acid prepilin peptidases.

Tongue coating and tongue brushing: a literature review

The present paper reviews the role of the tongue as a habitat for oral microorganisms and the potential need for tongue cleaning as part of daily oral hygiene. In addition tongue coating is described. Many microorganisms have been found colonizing the dorsum of the tongue. Some studies find a positive effect to tongue brushing on bacterial counts on the tongue. On the other hand there are also studies that do not find any differences in bacterial counts before or after tongue brushing. Bacteria colonizing the tongue and periodontal pockets play an important role in the production of volatile sulphur compounds in periodontal health and disease. These compounds can be the cause of oral malodour. The amount of tongue coating in patients complaining of halitosis was significantly greater than in patients without halitosis. Tongue brushing on a regular basis, particular aiming at removing the coating on the dorsum of the tongue, has been found to be fruitful in reducing oral malodour. Studies investigating the role of tongue brushing and plaque accumulation or gingival inflammation show conflicting results. It is clear that the tongue forms the largest niche for microorganims in the oral cavity. However, on the basis of literature, there appears to be no data to justify the necessity to clean the tongue on a regular basis. One exception would be oral malodour.

Identification of oral bacteria associated with crevicular epithelial cells from chronic periodontitis lesions

Bacterial invasion of host epithelial cells plays an important role in the pathogenesis of periodontal diseases; however, the interactions between subgingival species and the gingival crevice cells are not fully understood. This study determined the prevalence of a group of oral bacterial species on or in epithelial cells derived from periodontal pockets and the gingival crevice of subjects with periodontitis. Samples of epithelial cells were obtained from 120 sites with periodontal pockets > or =4 mm and 92 periodontally healthy sites from 49 patients (mean age 46.3+/-1.4 years; 43% males) with chronic periodontitis. Bacteria in or on epithelial cells were separated from unattached bacteria by Percoll density-gradient centrifugation. The presence and levels of 33 oral species were determined in epithelial cell samples by whole genomic DNA probes and the checkerboard method. The most frequently detected species were Porphyromonas gingivalis (42%), Treponema denticola (38%), Prevotella intermedia (37%), Streptococcus intermedius (36%), Campylobacter rectus (35%), Streptococcus sanguinis (35%) and Streptococcus oralis (34%). Species of Actinomyces were found in low prevalence and levels. The data indicated that there were more micro-organisms on or in epithelial cells obtained from periodontal pockets than from healthy sulci; however, no significant differences regarding the percentage and level of any specific species were found between these sites. Veillonella parvula, S. oralis, Streptococcus gordonii and Streptococcus mitis tended to be more prevalent in sites without disease. These findings demonstrated that a wide range of oral species may be detected on or in crevicular epithelial cells from sites with periodontitis and from periodontally healthy sulci.

Oral lactobacilli in chronic periodontitis and periodontal health: species composition and antimicrobial activity

BACKGROUND/AIMS

Lactobacilli are known to play an important role in the maintenance of health by stimulating natural immunity and contributing to the balance of microflora. However, their role in chronic periodontitis is unclear. We aimed to identify oral lactobacilli in chronic periodontitis and periodontally healthy subjects, and to determine their antimicrobial activity against putative oral pathogens.

METHODS

A total of 238 Lactobacillus isolates from the saliva and subgingival sites of 20 chronic periodontitis and 15 healthy subjects were collected. In all, 115 strains were identified using rapid amplified ribosomal DNA restriction analysis. Antimicrobial activity against Streptococcus mutans, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia was assessed.

RESULTS

Lactobacilli belonging to 10 species were identified. The most prevalent strains in healthy persons were Lactobacillus gasseri and Lactobacillus fermentum and in chronic periodontitis patients, Lactobacillus plantarum. Obligately homofermentatives, particularly L. gasseri, were less prevalent in chronic periodontitis patients compared with healthy subjects (8% vs. 64% for L. gasseri, P < 0.01). Sixty-nine percent of tested lactobacilli inhibited S. mutans, 88% A. actinomycetemcomitans, 82% P. gingivalis and 65% P. intermedia. The strongest antimicrobial activity was associated with Lactobacillus paracasei, L. plantarum, Lactobacillus rhamnosus, and Lactobacillus salivarius. The strains from periodontally healthy patients showed a lower antimicrobial activity against S. mutans than the strains from chronic periodontitis patients.

CONCLUSION

The composition of oral lactoflora in chronic periodontitis and healthy subjects differs, with a higher prevalence of homofermentative lactobacilli, particularly L. gasseri, in the latter group. Both homo- and heterofermentative oral lactobacilli suppress the growth of periodontal pathogens, but the antimicrobial properties are strain, species and origin specific.

Transmission of periodontal bacteria and models of infection

BACKGROUND

Bacteria play an essential role in the aetiology of periodontitis. Most bacterial species isolated from subgingival plaque are indigenous to the oral cavity. Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis are detected infrequently in periodontal health, which makes these species prime candidates to study person-to-person transmission. The aim of the present study was to review the literature on transmission of these periodontal bacterial species.

METHOD

We review the literature on bacterial typing techniques and summarize the information on clonal distribution of A. actinomycetemcomitans and P. gingivalis in family units based on different typing techniques in order to establish the likelihood for person-to-person transmission of these periodontal pathogens.

RESULTS

Vertical transmission of A. actinomycetemcomitans is estimated to be between 30% and 60%, whereas vertical transmission of P. gingivalis has rarely been observed. Horizontal transmission between spouses ranges between 14% and 60% for A. actinomycetemcomitans and between 30% and 75% for P. gingivalis. There is some evidence to show that cohabitation with a periodontitis patient influences the periodontal status of the spouse; however, substantially more information is needed to prove this hypothesis.

CONCLUSIONS

Transmission of putative periodontal pathogens between family members has been shown. The clinical consequences of these events have been poorly documented. Based on the current knowledge, screening for and prevention of transmission of specific virulent clones of A. actinomycetemcomitans may be feasible and effective in preventing some forms of periodontal disease. P. gingivalis is usually recovered from diseased adult subjects, and transmission of this pathogens seems largely restricted to adult individuals. Horizontal transmission of P. gingivalis may therefore be controlled by periodontal treatment involving elimination or significant suppression of the pathogen in diseased individuals and by a high standard of oral hygiene.

Association between sharing of toothbrushes, eating and drinking habits and the presence of Actinobacillus actinomycetemcomitans in Moroccan adolescents

BACKGROUND/AIMS

Actinobacillus actinomycetemcomitans is frequently detected in dental plaque collected from Moroccan adolescents, and has been shown to be associated with clinical attachment loss in this population. The aim of this study was to assess whether behaviors such as the sharing of toothbrushes, and eating and drinking habits were associated with the presence of A. actinomycetemcomitans in Moroccan adolescents.

MATERIALS AND METHODS

A total of 121 adolescents were clinically examined. Interviews regarding sharing of toothbrushes, eating and drinking habits were performed, and plaque samples were collected and analyzed for A. actinomycetemcomitans with different leukotoxin promoter types by polymerase chain reaction. Based on eating and drinking habits, the study population was divided in a low risk behavior group (LRB) and a high risk behavior group (HRB).

RESULTS

No association was found between the sharing of toothbrushes and the presence of A. actinomycetemcomitans. The odds ratios between the HRB and LRB group for being positive for the JP2 type, for non-JP2 types, and for any type of A. actinomycetemcomitans were 4.74 (95% CI 0.55; 40.71), 2.49 (95% CI 1.03; 5.97), and 2.97 (95% CI 1.28; 6.91), respectively. The difference in the mean number of teeth with a clinical attachment loss of > or = 3 mm between the HRB and the LRB group was 0.91(95% CI 0.09; 1.72).

CONCLUSION

Sharing of toothbrushes does not seem to be associated with the presence of A. actinomycetemcomitans in young Moroccans. Eating and drinking habits conducive to exchange of saliva are positively associated with presence of A. actinomycetemcomitans, and with a higher level of clinical attachment loss.

Effects of single-visit full-mouth ultrasonic debridement versus quadrant-wise ultrasonic debridement

BACKGROUND

The aim of this randomized controlled clinical trial was to determine the effects of single-visit full-mouth ultrasonic debridement versus quadrant-wise therapy.

MATERIAL AND METHODS

Thirty-six subjects with chronic periodontitis, were randomly allocated to three groups--quadrant-wise ultrasonic debridement, single-visit full-mouth ultrasonic debridement with povidone iodine and single-visit full-mouth ultrasonic debridement with water. Whole-mouth plaque, bleeding on probing (BOP), pocket depth and attachment level were recorded before treatment and 1, 3 and 6 months post-treatment. Plaque and saliva samples were collected for microbiological analysis.

RESULTS

After treatment, all groups showed significant improvement in clinical parameters. Full-mouth treatments resulted in similar improvements in full-mouth mean plaque percentage, probing pocket depth and probing attachment level as conventional therapy. When data were analysed based on pocket depth and tooth type, there was no difference between groups in probing depth reduction or attachment gains. The full-mouth groups demonstrated greater reduction in BOP% and number of pockets > or =5 mm and the total treatment time was significantly shorter. The detection frequencies of periodontal pathogens in plaque and saliva showed slight changes with no difference between groups.

CONCLUSION

Single-visit full-mouth mechanical debridement may have limited additional benefits over quadrant-wise therapy in the treatment of periodontitis, but can be completed in a shorter time.

Periodontal dressing (VocopacR) influences outcomes in a two-step treatment procedure

OBJECTIVES

It is not clear if periodontal dressing influences the long-term results in a non-surgical treatment procedure.

MATERIAL AND METHODS

The periodontal parameters (pre-baseline) of 36 patients with aggressive periodontitis were obtained before the patients were treated initially (1st step) by a dental hygienist, who completely removed the supra- and subgingival concrements. Baseline parameters were raised 3 weeks after the 1st step, before the 2nd therapy step was conducted. It consisted of a non-surgical procedure, which comprised a closed full-mouth manual root curettage (root planing), immediate systemic application of metronidazole, and the placement of a periodontal dressing (Vocopac, Voco). The patients were randomized to two test groups having their periodontal packs removed after 3-4 days (group 1, n=12) and 7-8 days (group 2, n=12), respectively and a control group (n=12) without periodontal dressing. Clinical parameters were raised again after 6 and 24 months.

RESULTS

Six and 24 months later, changes in probing pocket depth (PPD) and probing attachment level (PAL) were observed in all three groups compared with baseline, but the difference was significant in group 2 only. In addition, group 2 showed a greater reduction in mean PPD and also a significantly greater gain of attachment in comparison with the controls.

CONCLUSION

Wound dressing has a positive effect on clinical long-term results using a two-step non-surgical procedure. Moreover, removing the dressing after 7-8 days leads to clearly better results than removing it earlier.

The effect of periodontal treatment on the salivary bacterial load and early plaque formation

AIM

The purpose of the present study was to investigate in periodontitis patients the relationship between the number of bacteria in the saliva and the amount of de novo plaque formation before and after treatment.

METHODS

At baseline, before any treatment was provided, patients rinsed with 10 ml sterile saline. After professional tooth cleaning the patients were instructed to abolish all tooth cleaning procedures for the subsequent 24 h. After this period, the rinsing procedure was repeated and the amount of de novo plaque was assessed. Three months after the initial periodontal therapy was completed the experiment was repeated. The microbiological evaluation of the rinsing samples was carried out by means of phase contrast microscopy and anaerobic culturing.

RESULTS

After treatment the amount of de novo plaque was less compared to before treatment, 0.40 and 0.65 respectively. Both before and after treatment more de novo plaque was present at sites with inflammation than at healthy sites. In order to evaluate the contribution of the numbers of salivary bacteria to the amount of de novo plaque formation an analysis was carried out for healthy sites. This analysis included only healthy sites as determined before treatment and the same sites after treatment. The results showed a significant reduction in the de novo plaque formation after treatment (0.49 before and 0.22 after treatment). Phase contrast microscopic evaluation showed that the number of bacteria in the rinsing samples after treatment was less than before treatment. After treatment also a reduction was found in the prevalence of Prevotella intermedia, Tannerella forsythensis and Peptostreptococcus micros in the rinsing samples.

CONCLUSION

The present study confirms the observation in the literature that the periodontal condition is of major importance in the rate of de novo plaque formation. In addition, the results suggest that the number of bacteria in the saliva may play a role.

Quantitative detection of periodontal pathogens using real-time polymerase chain reaction with TaqMan probes

Quantitative analysis, with identification of periodontopathic bacteria, is important for the diagnosis, therapeutic evaluation and risk assessment of periodontal disease. We developed a highly sensitive and specific method using real-time polymerase chain reaction (PCR) to detect and quantify six periodontal bacteria: Porphyromonas gingivalis, Tannerella forsythia, Actinobacillus actinomycetemcomitans, Treponema denticola, Prevotella intermedia, and Prevotella nigrescens. Species-specific TaqMan probe/primer sets were designed according to 16S ribosomal RNA gene sequences. Plaque and tongue debris specimens were collected from 10 patients with advanced periodontitis and 10 periodontal healthy individuals and analyzed. All species, except for P. nigrescens, were detected in samples from diseased sites in significantly greater numbers than in those from healthy sites, whereas greater numbers of P. nigrescens were found in the controls. These results suggest that the present real-time PCR method with the designed probe/primer sets enabled sensitive detection of the six periodontal bacteria, and may also assist future microbial studies of periodontal diseases.

Effects of periodontitis and smoking on the microbiota of oral mucous membranes and saliva in systemically healthy subjects

BACKGROUND/AIM

To examine the differences in the proportions of 40 bacterial species in samples from eight oral soft-tissue surfaces and saliva in systemically healthy adult subjects with and without periodontitis and in smokers and nonsmokers.

METHODS

Saliva and microbial samples were taken from eight oral soft-tissue surfaces in 229 systemically healthy subjects stratified by periodontal and smoking status. Subjects included 84 periodontally healthy and 145 periodontitis individuals. Of these, there were 182 nonsmokers and 47 smokers. Soft-tissue samples were taken using a "buccal brush" and saliva was taken by expectoration. All samples were individually evaluated for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The percentage of total DNA probe count was determined for each species at each sample location and averaged across subjects. The significance of differences among the proportions of the 40 test species at different sample locations was sought in these populations using the Kruskall-Wallis test and adjusted for multiple comparisons.

RESULTS

When stratified for periodontal status or smoking status, microbial profiles at most sites did not differ significantly. Generally, periodontal pathogens were found at higher levels on the soft tissues of periodontitis subjects than in periodontally healthy subjects, and at higher levels in smokers than nonsmokers. Few significant differences were found, although trends in the populations were noted.

CONCLUSIONS

Small differences in the proportions of bacterial species were observed on soft tissues and in saliva comparing periodontally healthy and periodontitis subjects. Somewhat greater differences between smokers and nonsmokers were found; however, these were not statistically significant.

Molecular pathogenicity of the oral opportunistic pathogen Actinobacillus actinomycetemcomitans

Periodontitis is mankind's most common chronic inflammatory disease. One severe form of periodontitis is localized aggressive periodontitis (LAP), a condition to which individuals of African origin demonstrate an increased susceptibility. The main causative organism of this disease is Actinobacillus actinomycetemcomitans. A member of the Pasteurellaceae, A. actinomycetemcomitans produces a number of interesting putative virulence factors including (a) an RTX leukotoxin that targets only neutrophils and monocytes and whose action is influenced by a novel type IV secretion system involved in bacterial adhesion; (b) the newly discovered toxin, cytolethal distending toxin (CDT); and (c) a secreted chaperonin 60 with potent leukocyte-activating and bone resorbing activities. This organism also produces a plethora of proteins able to inhibit eukaryotic cell cycle progression and proteins and peptides that can induce distinct forms of proinflammatory cytokine networks. A range of other proteins interacting with the host is currently being uncovered. In addition to these secreted factors, A. actinomycetemcomitans is invasive with an unusual mechanism for entering, and traveling within, eukaryotic cells. This review focuses on recent advances in our understanding of the molecular and cellular pathogenicity of this fascinating oral bacterium.

Effect of various chlorhexidine regimens on salivary bacteria and de novo plaque formation

AIM

The aim of the present experiment was to study the effect of different chlorhexidine regimens on the number of bacteria in saliva, and on de novo plaque formation.

MATERIAL AND METHODS

Ten subjects with gingivitis, but no signs of destructive periodontitis, were recruited. Following a screening examination, the volunteers were given oral hygiene instruction, meticulous scaling and professional mechanical tooth cleaning (PTC). The PTC was repeated once every 3 days during a 2-week period to establish healthy gingival conditions. The study was designed as a double-blind cross-over clinical trial including three phases. Each experimental phase comprised one preparatory period of 7 days and one plaque accumulation period (no oral hygiene measures) of 4 days. During all preparatory periods, the volunteers (i) performed mechanical tooth cleaning using a toothbrush and dentifrice and (ii) were, in addition, given two sessions of PTC. The final PTC was delivered after bacterial sampling had been made on Day 0. Preparatory period A: the participants continued the self-performed plaque control regimen that employed only mechanical means. Preparatory period B: the participants were in addition instructed to rinse and gargle, twice daily, with a 0.2% chlorhexidine mouthrinse. Preparatory period C: in addition to the above, the participants were instructed to brush the dorsum of the tongue for 60 s, twice daily, with a 1.0% chlorhexidine gel. Following each plaque accumulation period, there was a 10-day washout interval. The presence and amount of dental plaque (QHI) was scored after 1, 2 and 4 days of no oral hygiene. Samples of saliva were obtained on Day 0 and after 1 and 2 days. The samples were placed on Brucella agar plates and incubated (anaerobically) for 5 days. The total number of colony-forming units was determined and used to estimate the density of bacteria in saliva.

RESULTS

In period A, the mean QHI increased from 1.0 (Day 1) to 1.4 (Day 2) and 2.1 (Day 4). The corresponding scores for periods B and C were 0.5, 0.8, 1.6 and 0.3, 0.8, 1.2, respectively. At all re-examination intervals more plaque formed during period A than during periods B and C. Further, during period C, less plaque formed than that during period B. Saliva samples from Day 0 in period A contained a larger number of TVC than the baseline samples in periods B and C. There was no significant difference in TVC among the groups on Day 2.

CONCLUSION

The daily use of chlorhexidine as an adjunct to mechanical tooth cleaning markedly reduced the number of microorganisms that could be detected in saliva. The number of salivary bacteria may have influenced the amount of plaque that formed during an early phase of no oral hygiene.

The diagnostic applications of saliva--a review

This review examines the diagnostic application of saliva for systemic diseases. As a diagnostic fluid, saliva offers distinctive advantages over serum because it can be collected non-invasively by individuals with modest training. Furthermore, saliva may provide a cost-effective approach for the screening of large populations. Gland-specific saliva can be used for diagnosis of pathology specific to one of the major salivary glands. Whole saliva, however, is most frequently used for diagnosis of systemic diseases, since it is readily collected and contains serum constituents. These constituents are derived from the local vasculature of the salivary glands and also reach the oral cavity via the flow of gingival fluid. Analysis of saliva may be useful for the diagnosis of hereditary disorders, autoimmune diseases, malignant and infectious diseases, and endocrine disorders, as well as in the assessment of therapeutic levels of drugs and the monitoring of illicit drug use.

Can presence or absence of periodontal pathogens distinguish between subjects with chronic and aggressive periodontitis? A systematic review

OBJECTIVES

The purpose of this study was to determine to what extent the presence or absence of periodontal pathogens can distinguish between subjects with chronic and aggressive periodontitis.

MATERIAL AND METHODS

A systematic review of cross sectional and longitudinal studies providing microbiological data both from patients with chronic periodontitis (ChP) and aggressive periodontitis (AgP) at a subject level. Strict inclusion criteria were applied. The presence or absence of five microorganisms was selected as primary study parameters: Actinobacillus actinomycetemcomitans (AA), Porphyromonas gingivalis (PG), Prevotella intermedia (PI), Bacteroides forsythus (BF), and Campylobacter rectus (CR).

RESULTS

The presence or absence of AA could be evaluated in 11 papers. In seven papers the presence or absence of PG could be analysed. Subject specific data on PI were available from six studies. Two studies could be used regarding the presence or absence of BF, and two regarding CR. Sensitivity and specificity of every microbiological test were individually calculated for each selected study, assuming that the clinical diagnosis of AgP or ChP was the true status the tests attempted to detect. AgP was considered to be the condition of interest and ChP was considered equivalent to 'non-AgP'. Receiver Operator Characteristic (ROC) diagrams were constructed using these data. ROC diagrams indicated the limited discriminatory ability of all of the test parameters to identify subjects with AgP. An additional assessment showed that the highly leukotoxic variant of AA was uniquely associated with patients suffering from aggressive periodontitis. However, in a high proportion of patients diagnosed with AgP the presence of this variant could not be detected.

CONCLUSION

The presence or absence of AA, PG, PI, BF or CR could not discriminate between subjects with AgP from those with ChP.

Distribution of selected bacterial species on intraoral surfaces

BACKGROUND/AIM

To examine the proportions of 40 bacterial species in samples from 8 oral soft tissue surfaces and saliva in systemically healthy adult subjects and to compare these microbiotas with those of supra- and subgingival plaque.

METHODS

Microbial samples were taken from 8 oral soft tissue surfaces of 225 systemically healthy subjects using a "buccal brush". Saliva was taken by expectoration. Forty-four of these subjects provided additional supra- and subgingival plaque samples. Samples were individually evaluated for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The percentage of total DNA probe count was determined for each species, at each sample location and averaged across subjects. The significance of differences among the proportions of the 40 test species at different sample locations was sought in the 225 and 44 subjects separately using the Quade test and adjusted for multiple comparisons. Cluster analysis was performed using the proportions of the 40 species at the different sample locations using the minimum similarity coefficient and an average unweighted linkage sort. The proportions of each species were averaged across subjects in the resulting cluster groups and the significance of differences was tested using the t-test and ANOVA.

RESULTS

Microbial profiles differed markedly among sample locations in the 225 subjects, with 34 of 40 species differing significantly. Proportions of Veillonella parvula and Prevotella melaninogenica were higher in saliva and on the lateral and dorsal surfaces of the tongue, while Streptococcus mitis and S. oralis were in significantly lower proportions in saliva and on the tongue dorsum. Cluster analysis resulted in the formation of 2 clusters with >85% similarity. Cluster 1 comprised saliva, lateral and dorsal tongue surfaces, while Cluster 2 comprised the remaining soft tissue locations. V. parvula, P. melaninogenica, Eikenella corrodens, Neisseria mucosa, Actinomyces odontolyticus, Fusobacterium periodonticum, F. nucleatum ss vincentii and Porphyromonas gingivalis were in significantly higher proportions in Cluster 1 and S. mitis, S. oralis and S. noxia were significantly higher in Cluster 2. These findings were confirmed using data from the 44 subjects providing plaque samples. The microbial profiles of supra- and subgingival plaque differed from the other sample locations, particularly in the increased proportions of the Actinomyces species. Species of different genera exhibited different proportions on the various intraoral surfaces, but even within the genus Streptococcus, there were differences in colonization patterns. S. oralis, S. mitis and S. constellatus colonized the soft tissues and saliva in higher proportions than the samples from the teeth, while the other 4 streptococcal species examined colonized the dental surfaces in proportions comparable to the soft tissue locations and saliva.

CONCLUSIONS

Proportions of bacterial species differed markedly on different intraoral surfaces. The microbiota of saliva was most similar to that of the dorsal and lateral surfaces of the tongue. The microbiotas of the soft tissues resembled each other more than the microbiotas that colonized the teeth both above and below the gingival margin.

Susceptibilities of different Actinobacillus actinomycetemcomitans strains to lactoperoxidase-iodide-hydrogen peroxide combination and different antibiotics

Actinobacillus actinomycetemcomitans has an important aetiological role in localized juvenile periodontitis and in progressive periodontitis in adults. A. actinomycetemcomitans is found mainly in periodontal pockets but also in whole saliva, a potential transmission medium. It is sensitive to peroxidase-halide systems, but the differences between periodontitis associated clinical isolates and type strains are unclear. The sensitivities of these 2 strain groups to lactoperoxidase (LP)-iodide (I(-))-hydrogen peroxide (H(2)O(2)) combinations were investigated, and the sensitivities were compared with the susceptibilities to four antibiotics. There was great variation between the sensitivities of different strains, but the 2 strain groups responded similarly. The LP (75 microg)-I(-) (100 nmol)-H(2)O(2) (1000 nmol) combination produced a similar degree of inhibition as 2 microg ampicillin. The LP-I(-) system might be a potential antimicrobial agent against A. actinomycetemcomitans transmission via saliva.

Guided tissue regeneration using a polylactic acid barrier. Part I: Environmental effects on bacterial colonization

OBJECTIVES

The purpose of this study was to assess the dynamics of bacterial colonization in intra-osseous defects following guided tissue regeneration (GTR) therapy using a resorbable barrier.

PATIENTS AND METHODS

In each of 30 patients, one intra-osseous defect was treated with GTR using a polylactic acid membrane (Guidor). Plaque samples were taken from the defect site, other teeth and mucous membranes following initial therapy (baseline), and at 3, 6 and 12 months after periodontal surgery. Additionally, samples were taken from the defect sites at 1, 2 and 4 weeks. Actinobacillus actinomycetemcomitans (A.a.), Porphyromonas gingivalis (P.g.), and Bacteroides forsythus (B.f.) were detected by polymerase chain reaction (PCR). Supportive periodontal therapy was performed at 3-month intervals.

RESULTS

In the 29 patients completing the study, the assessed microflora was detected in 3 (A.a.), 13 (P.g.) and 14 (B.f.) defect sites at baseline, in 2 (A.a.), 2 (P.g.) and 2 (B.f.) following surgical debridement, and in 6 (A.a.), 10 (P.g.) and 22 (B.f.) at 12 months. Defect site colonization following GTR therapy was significantly correlated with presurgical colonization at other assessed teeth (A.a. and P.g.: tau = 0.45 and 0.66, respectively; P < 0.001), or on mucous membranes (B.f.: tau = 0.44, P < 0.001).

CONCLUSION

The colonization of periodontal pathogens at sites treated by GTR may correlate with the intra-oral presence of these pathogens before surgery. If colonization of GTR sites by periodontal pathogens is to be prevented, intra-oral suppression/eradication of these pathogens may be required before surgery.