Periodontal diseases in Thai schoolchildren. Clinical and microbiological observations.

The prevalence of periodontitis among Thai schoolchildren is unknown. In a cross-sectional study, the prevalence and severity of periodontal diseases, in a group of Thai schoolchildren, along with the presence and numbers of bacterial species commonly associated with periodontitis were investigated. A consent form was sent out to 192 schoolchildren in one school (Chanachanupathom School) in Chana, Southern Thailand (in the age range of 12-18 years) and 119 attended for a clinical and microbiological examination. Clinical recordings included number of teeth present, DMFT, plaque index, bleeding index, clinical attachment loss (CAL), and probing pocket depth (PPD). Pooled plaque samples were analyzed with culture and qPCR against bacteria associated with periodontitis. The children had low caries experience (DMFT = 3.2 ± 2.3), poor oral hygiene, high bleeding scores, and 67 (56.3%) had at least one interproximal site with CAL ≥ 1 mm. Thirty-seven (31.1%) of the children were diagnosed with periodontitis stage I, and sixteen (13.4%) were classified as periodontitis Stage II. Aggregatibacter actinomycetemcomitans was sparsely found in all but the healthy clinical groups (gingivitis, periodontitis Stage I and II), while the groups showed a high prevalence of Fusobacterium spp., Prevotella intermedia/nigrescens, and Campylobacter species as well as of the periodontitis-associated species Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia. Thai schoolchildren have poor oral hygiene with abundant amounts of plaque and high presence of bleeding. Early onset periodontitis is common but mostly in its mild form and is not associated with the presence of A. actinomycetemcomitans.

A comparative study on periodontitis and periodontitis-associated bacteria in Somali and non-Somali children and adolescents living in Trollhättan, Sweden.

The reported prevalence of periodontitis in children and adolescents varies considerably between populations globally. This cross-sectional study compares clinical and microbiological findings on 83 Somali immigrants and 96 non-Somali children aged 10-17 years old living in Trollhättan, Sweden. The clinical examination included registration of bleeding on probing, plaque, and calculus on incisors and first molars. The distance between cemento-enamel junction and bone level was measured on bitewing radiographs. Pooled microbiological samples (1 µL) were taken from the mesial surface of 16, 11, 31, 36, and analyzed by culture and real-time polymerase chain reaction for seven periodontal associated bacterial species. The Somali participants had poorer oral hygiene and more bleeding, plaque, and calculus. Ten of the Somali but none of the non-Somali participants showed periodontal breakdown (radiographical bone loss > 3 mm), corresponding to a prevalence of 12% (95% CI: 5.9, 21.0%). The presence of A. actinomycetemcomitans was almost exclusively associated with Somali participants. Further, the JP2 clone was found in five Somalis (including two periodontitis cases) confirming the association of this clone with African populations. The Somali group showed significantly higher frequencies and numbers of Porphyromonas gingivalis and Treponema denticola, implying a mature and adult type of subgingival microbiota.

Effect of biofilm formation on implant abutments with an anti-bacterial coating: A pre-clinical in vivo study.

OBJECTIVES: To analyse the long-term effect of plaque formation on implant abutments with an antibacterial coating and the ensuing host response in peri-implant tissues. MATERIALS AND METHODS: Four implants were installed in each mandibular premolar region following tooth extraction in six dogs. Three months later, two test abutments with a titanium-bismuth-gallium (Ti-Bi-Ga) coating and two control titanium abutments were connected to the implants on each side of the mandible. After 2 months, ligatures were placed around the implants in one side of the mandible and plaque formation was allowed until the end of the experiment. The ligatures were removed after 4 weeks. Radiographs and microbiological samples were obtained from each implant site during the plaque formation period. Biopsies were obtained 8 months after abutment connection and prepared for histological analysis. RESULTS: The analysis did not reveal any statistically significant differences in bone loss, bacterial growth and size of inflammatory lesions between implant units with and without the Ti-Bi-Ga coating. Implant sites exposed to the short period of ligature-induced breakdown demonstrated more pronounced bone loss and bacterial growth than non-ligature sites. CONCLUSIONS: It is suggested that a Ti-Bi-Ga coating does not prevent biofilm formation on the implant device and does not influence the ensuing host response in the adjacent peri-implant mucosa.

Oral Lactobacillus strains reduce cytotoxicity and cytokine release from peripheral blood mononuclear cells exposed to Aggregatibacter actinomycetemcomitans subtypes in vitro.

BACKGROUND: This study evaluated the effect of oral lactobacilli on the cytotoxicity and cytokine release from peripheral blood mononuclear cells (PBMCs) when exposed to Aggregatibacter actinomycetemcomitans subtypes in vitro. The supernatants and cell wall extracts (CWEs) of eight A. actinomycetemcomitans strains, representing different subtypes, and three Lactobacillus strains were used. The PBMCs from six blood donors were exposed to supernatants and CWEs of A. actinomycetemcomitans or Lactobacillus strains alone or combinations and untreated cells as control. The cytotoxicity was determined by trypan blue exclusion method and IL-1ß secretion by ELISA. TNF-α, IL-6, and IL-8 secretions were measured using Bioplex Multiplex Immunoassay. RESULTS: Supernatants or CWEs from all bacterial strains showed cytotoxicity and IL-1ß secretion and the subtypes of A. actinomycetemcomitans showed generally a significantly higher effect on PBMCs than that of the Lactobacillus strains. Two highly toxic A. actinomycetemcomitans strains (JP2 and JP2-like) induced a higher response than all other strains. When combined, Lactobacillus significantly reduced the toxicity and the IL-1ß secretion induced by A. acinomycetemcomitans. The effect varied between the subtypes and the reduction was highest for the JP2 and JP2-like strains. The Lactobacillus paracasei strain SD1 had a higher reducing effect than the other Lactobacillus strains. This strain had a consistent reducing effect on all subtypes of A. actinomycetemcomitans cytotoxicity, and release of IL-1ß, IL-6, IL-8, and TNF-α from PBMCs of the blood donors. A strong and significant variation in cytokine release between the six blood donors was noticed. CONCLUSIONS: Lactobacillus spp. and L. paracasei SD1 in particular, showed a limited but statistically significant reducing interaction with A. actinomycetemcomitans toxicity and release of cytokines in vitro.

Periodontitis phenotypes and clinical response patterns to non-surgical periodontal therapy: reflections on the new periodontitis classification.

We aimed to identify response patterns to non-surgical periodontal therapy and to investigate whether the new classification system for periodontitis reflects response to treatment after 1 yr. At baseline, data on sociodemographic status, smoking, and diabetes were obtained from participants with periodontal disease. Clinical periodontal data and subgingival plaque were also collected. Participants underwent non-surgical periodontal therapy, and after 3 and 12 months, clinical data were reassessed. Factor analyses, group-based-trajectory modeling, and mixed-effects regression models were used for data analysis. Factor analysis of the baseline periodontal parameters revealed two different periodontitis dimensions: 'moderate' and 'severe'. Two response patterns for each of these periodontitis dimensions were identified. Periodontal therapy had a beneficial effect on both 'moderate' and 'severe' periodontitis; however, individuals with higher levels of disease at baseline experienced greater treatment effect. Regarding the new classification system, while the staging component distinguished different levels of 'moderate' and 'severe' periodontitis before and after treatment, the grading component did not. This study shows the beneficial effect of non-surgical periodontal therapy on both 'moderate' and 'severe' periodontitis. However, the benefit was limited among individuals with low levels of disease. The new classification system did not adequately reflect the periodontal response to therapy in this patient group.

Current concepts and an alternative perspective on periodontal disease.

BACKGROUND: Epidemiological data from countries worldwide show a consistent pattern implying that a fraction of around 10% of those over 40-50 years in all populations will exhibit severe periodontitis with the potential risk of losing teeth during their life-time. The subgingival microbiota shows striking similarities between populations irrespective of disease severity and can only marginally explain the clinical pattern. It is also difficult to explain this pattern by genetic and acquired risk factors such as systemic disease (e.g. diabetes) or habits (e.g. smoking) even if they may have a confounding effect on the disease. MAIN TEXT: Inflammation of the gingiva appears to be a normal and physiological response to the presence of commensal bacteria along the gingival crevice and in the dental biofilm. Over many years of exposure to the dental biofilm, the chronic inflammation in the gingiva gradually results in a loss of attachment and bone loss. Numerous laboratory and clinical studies have provided insight into the potential role of determinants that are associated with periodontitis. However, it has been difficult to relate the findings to the pattern of the distribution of the disease observed in epidemiological studies. We propose a simple and parsimonious model that considers all the multitude of potential determinants as creating effectively random noise within the dental biofilm to which the tissues react by accumulating the effects of this noise. CONCLUSIONS: We suggest that such a model can explain many of the epidemiological features of periodontal breakdown over time, and we discuss its clinical implications.

Comparison of antimicrobial prescribing for dental and oral infections in England and Scotland with Norway and Sweden and their relative contribution to national consumption 2010-2016.

BACKGROUND: Prescribing in dental practice has a relatively small but important contribution to the quantity of antibiotics prescribed in primary care. This study aimed to analyse antibiotic prescribing in dentistry over time (2010-2016) in 4 different Northern European countries and their relative contribution to national outpatients consumption. METHODS: This retrospective study evaluated the frequency and number of national antibiotic prescriptions written by dentists in England, Scotland, Norway and Sweden. The consumption of such antibiotics was measured using WHO defined daily doses (DDDs), DDDs per 100,000 inhabitants per day (DIDs100,000). RESULTS: A total of more than 27 million prescriptions (27,026,599) archived between 2010 and 2016 from the four countries were analysed. The national contribution of Norwegian dentists to the total primary care prescription during this period was 8%. The corresponding figures for Sweden, Scotland and England were 7, 6, and 8%. Dental contribution to National antibiotic use in all four countries has decreased over the study time period for commonly prescribed antibiotics in dentistry, i.e., the beta-lactams (Phenoxymethyl penicillin/Amoxicillin) and metronidazole. There were less numbers of prescriptions by dentists in Norway and Sweden compared to England and Scotland. Marked differences in some classes of antibiotics were noted with Phenoxymethyl penicillin dominating in Sweden/Norway compared to Amoxicillin and Metronidazole in England/Scotland. In England and Scotland, dentists were the largest prescribers of metronidazole in primary care. Clindamycin prescriptions was higher in Norway and Sweden. CONCLUSION: Noticeable differences exist in prescribing patterns for the management of oral infections. High levels of metronidazole use in England and Scotland also require further analysis. All countries over the study period showed a decrease in total numbers of antibiotics prescribed.

The furcation tunnel preparation-A prospective 5-year follow-up study.

AIM: The aim of this study was to prospectively follow furcation tunnelled molars over a 5-year period of supportive periodontal therapy (SPT) and to identify factors associated with tooth loss. MATERIALS AND METHODS: A total of 32 patients with 42 furcation tunnelled molars (all class III prior tunnelling) were recruited upon commencing SPT following active periodontal therapy. Clinical registrations, bacterial samples and standardised radiographs were taken at baseline, year 1 (no radiographs), 2 and 5. Total viable counts, total streptococci, Streptococcus sanguinis and mutans streptococci (MS) were identified through culture, a panel of periodontal pathogens through the checkerboard technique. RESULTS: After 5 years, 29 molars (69%) were still in function. Of the lost molars, eight were upper and five lower molars. Recurrent periodontal disease and caries were reasons for tooth loss. A multilevel regression analysis showed that a smoking habit, bleeding on probing and the presence of MS in furcations were associated with an increased risk of tooth loss. CONCLUSIONS: Furcation tunnelled molars can in most cases be kept over a period of 5 years of SPT. A smoking habit, baseline bleeding scores and the presence of MS in the furcation were risk indicators for loss.

The cultivable bacterial flora of the esophagus in subjects with esophagitis.

BACKGROUND: The healthy human esophagus is colonized by bacteria similar to that of the oral mucosa. However, little is known about the microbiome of the esophagus in esophagitis or the possible role of bacteria in the inflammatory response. AIM: To survey bacterial diversity and compare the microbiome of the esophagus in subjects with gastro-esophageal reflux disease (GERD) and eosinophilic esophagitis (EoE). MATERIAL AND METHODS: Seventeen subjects diagnosed with GERD and 10 with EoE underwent endoscopic examination with brush sampling and biopsies from the oral cavity, upper and lower esophagus. The samples were cultivated on agar plates, and bacterial growth was identified to the genus or species level and semi-quantified. RESULTS: Significantly higher numbers of bacterial groups or species were found in specimens from the lower esophagus in subjects with EoE compared to subjects with GERD (median 4 (range 1-7) vs. 2 (range 0-6), p < .0014). Sixteen vs. 14 different bacterial groups or species were found in subjects with GERD and EoE, respectively, mostly in sparse or very sparse amounts. Alfa-streptococci (viridans streptococci) were the most common bacteria in both groups. Streptococci were present in all of the EoE-subjects but only in approximately 75% in lower esophagus of the GERD-subjects, regardless of the sampling method. CONCLUSION: Subjects with GERD had significantly less bacterial diversity in both oral and esophageal samples than EoE-subjects. Whether this discrepancy might be explained by an effect on the protective mucosal biofilm by the acidic content of the reflux in subjects with GERD remains unclear.

Soluble urokinase-type plasminogen activator receptor is associated with signs of periodontitis in adolescents.

Owing to its molecular stability in body fluids, soluble urokinase-type plasminogen activator receptor (suPAR) is used as a biomarker for the level of systemic inflammation. This study compares the suPAR levels in serum with those in the saliva of adolescents and evaluates their association with the periodontal conditions. Adolescents identified as screen positive (n = 87) or screen negative (n = 73) for periodontitis had saliva and serum samples taken, along with subgingival plaque samples. The concentrations of suPAR were determined in saliva and serum, and 18 microbial species and the immunoglobulin response to them was evaluated. Factor analyses were used to reduce the number of variables within each of the domains of clinical, microbiological, and immunological findings. The median salivary suPAR concentration was 13.18 [(interquartile range (IQR): 6.20-23.36] µg l-1 and was not associated with the serum suPAR levels (median 2.05; IQR: 1.62-2.46 µg l-1 ). Linear regression analysis showed that the log10 (salivary suPAR concentration) was statistically significantly positively associated with the clinical phenotype 'Periodontitis Extent' (ß = 0.28; 95% CI: 0.16-0.39) along with 'Putative periodontopathogens' (ß = 0.65; 95% CI: 0.51-0.79). The study represents the first determination of salivary suPAR concentration in a larger well-defined adolescent population. Our results suggest the potential for clinical use of suPAR in saliva as an inflammatory risk indicator/biomarker of periodontitis.

Caries and Periodontitis: Contesting the Conventional Wisdom on Their Aetiology.

We review the literature on the oral microbiome and the role of the microbiota in the development of dental caries and periodontitis. While most research has been focused on identifying one or more specific determinants of these diseases, the results have provided limited predictive value and have not been able to explain the variation in the distribution of these diseases observed in epidemiological or clinical studies. Drawing on existing knowledge about the nature of the oral microbiota, we suggest that a stochastic model based on the Weiner process provides simple and parsimonious explanations for the pathogenesis of both caries and periodontitis, making few assumptions, and providing explanations for phenomena that have hitherto proved difficult, or have required complex arguments, to explain. These diseases occur as the result of the dental hard tissues and periodontal tissues integrating the random "noise" caused by normal metabolic activities of commensal microorganisms in the dental biofilm. The processes that result in the progression and regression of caries and periodontitis may be considered as "natural," rather than pathological, even if, when left unchecked over long periods of time, they can result in the development of pathologies. The likelihood of progression or regression can be influenced by other determinants, but these processes will nevertheless occur in the absence of such influences. The distributional characteristics of the model approximate the findings of epidemiological studies indicating that, for both caries and periodontitis, there will be few sites affected in the early period after the eruption of the permanent dentition, but in those older there is an almost linear relationship with increasing age; furthermore, the longer a site survives without being affected, the less likely that it will be affected. We discuss the clinical and public health importance of these findings.

Rapid urease test (RUT) for evaluation of urease activity in oral bacteria in vitro and in supragingival dental plaque ex vivo.

BACKGROUND: Urease is an enzyme produced by plaque bacteria hydrolysing urea from saliva and gingival exudate into ammonia in order to regulate the pH in the dental biofilm. The aim of this study was to assess the urease activity among oral bacterial species by using the rapid urease test (RUT) in a micro-plate format and to examine whether this test could be used for measuring the urease activity in site-specific supragingival dental plaque samples ex vivo. METHODS: The RUT test is based on 2% urea in peptone broth solution and with phenol red at pH 6.0. Oral bacterial species were tested for their urease activity using 100 µl of RUT test solution in the well of a micro-plate to which a 1 µl amount of cells collected after growth on blood agar plates or in broth, were added. The color change was determined after 15, 30 min, and 1 and 2 h. The reaction was graded in a 4-graded scale (none, weak, medium, strong). Ex vivo evaluation of dental plaque urease activity was tested in supragingival 1 µl plaque samples collected from 4 interproximal sites of front teeth and molars in 18 adult volunteers. The color reaction was read after 1 h in room temperature and scored as in the in vitro test. RESULTS: The strongest activity was registered for Staphylococcus epidermidis, Helicobacter pylori, Campylobacter ureolyticus and some strains of Haemophilus parainfluenzae, while known ureolytic species such as Streptococcus salivarius and Actinomyces naeslundii showed a weaker, variable and strain-dependent activity. Temperature had minor influence on the RUT reaction. The interproximal supragingival dental plaque between the lower central incisors (site 31/41) showed significantly higher scores compared to between the upper central incisors (site 11/21), between the upper left first molar and second premolar (site 26/25) and between the lower right second premolar and molar (site 45/46). CONCLUSION: The rapid urease test (RUT) in a micro-plate format can be used as a simple and rapid method to test urease activity in bacterial strains in vitro and as a chair-side method for testing urease activity in site-specific supragingival plaque samples ex vivo.

The proteins of Fusobacterium spp. involved in hydrogen sulfide production from L-cysteine.

BACKGROUND: Hydrogen sulfide (H2S) is a toxic foul-smelling gas produced by subgingival biofilms in patients with periodontal disease and is suggested to be part of the pathogenesis of the disease. We studied the H2S-producing protein expression of bacterial strains associated with periodontal disease. Further, we examined the effect of a cysteine-rich growth environment on the synthesis of intracellular enzymes in F. nucleatum polymorphum ATCC 10953. The proteins were subjected to one-dimensional (1DE) and two-dimensional (2DE) gel electrophoresis An in-gel activity assay was used to detect the H2S-producing enzymes; Sulfide from H2S, produced by the enzymes in the gel, reacted with bismuth forming bismuth sulfide, illustrated as brown bands (1D) or spots (2D) in the gel. The discovered proteins were identified with liquid chromatography - tandem mass spectrometry (LC-MS/MS). RESULTS: Cysteine synthase and proteins involved in the production of the coenzyme pyridoxal 5'phosphate (that catalyzes the production of H2S) were frequently found among the discovered enzymes. Interestingly, a higher expression of H2S-producing enzymes was detected from bacteria incubated without cysteine prior to the experiment. CONCLUSIONS: Numerous enzymes, identified as cysteine synthase, were involved in the production of H2S from cysteine and the expression varied among Fusobacterium spp. and strains. No enzymes were detected with the in-gel activity assay among the other periodontitis-associated bacteria tested. The expression of the H2S-producing enzymes was dependent on environmental conditions such as cysteine concentration and pH but less dependent on the presence of serum and hemin.

Pro-inflammatory cytokine responses in human gingival epithelial cells after stimulation with cell wall extract of Aggregatibacter actinomycetemcomitans subtypes.

Varying cytokine responses of human gingival epithelial cells (HGECs) by Aggregatibacter actinomycetemcomitans subtypes have been found. Most studies have used reference strains, whereas a few has evaluated the cytokine expression in response to clinical subtypes of this bacterial species. This study aimed to examine whether there was any difference in cytokine responses of HGECs stimulated with cell wall extract (CWE) from A. actinomycetemcomitans subtypes included clinical strains from Thai adult periodontitis, various serotypes and non-serotypeable strains, strains from deep or shallow pockets, and reference serotype strains. Totally 50 clinical strains and 7 reference strains of A. actinomycetemcomitans were analyzed for the expression of IL-1ß, IL-6, IL-8, and TNF-α mRNAs in HGECs by real time-PCR, and the IL-8 concentrations in cell-free supernatant measured using ELISA. An in vitro effect of released IL-8 on neutrophil migration was examined using transwell chambers. Result showed that among four cytokines studied, IL-8 mRNA was highly up-regulated by both clinical and reference strains. Serotype f revealed the highest expression compared to other serotypes. The JP2-like leukotoxin promoter gene and non-serotypeable (NS1 and NS2) demonstrated lower IL-8 responses compared to serotypeable strains, and IL-8 responses upon stimulation with clinical strains from deep pockets were also significantly lower than those isolated from shallow pockets (P < 0.01). Our findings suggest that the clinical isolates of A. actinomycetemcomitans associating with deep pockets, JP2-like leukotoxin promoter gene, NS1, and NS2 may interfere neutrophil function via minimal and immunosuppressing IL-8 responses, which may enhance their survival and virulence.

Subgingival bacterial clusters and serum antibody response as markers of extent and severity of periodontitis in adult Chinese.

This study evaluated the associations between clinical, microbiological, and antibody activity manifestations of periodontitis in 123 adult rural Chinese subjects with no dental intervention. All participants were registered for full-mouth clinical attachment level (CAL) and pocket probing depth (PD) measurements, and microbial samples were taken from four sites and analyzed for 18 different bacterial species using the 'checkerboard'. Serum from each individual was analyzed to determine the antibody activity against the same 18 species. Exploratory factor analysis disclosed two microbial factors - Factor 1, consisting of seven species associated with periodontal health ('early colonizers'); and Factor 2, consisting of eight species associated with periodontitis ('putative periodontopathogens') - which explained 87% of the variation among the microbial variables. Factor 2 was consistently associated with disease-severity measures, whereas the 'early colonizer' factor was not. The antibody response showed weak or no correlations with bacterial load or with disease severity. We conclude that the bacteria investigated are resident in the subgingival plaque; that their load and proportions in the pocket may be ecologically driven; and that the antibody response is based on bacterial carrier state rather than on disease. The different antibody-response pattern found between the individuals may suggest that each individual could be classified as a good or a weak immune responder.

Oral microflora in preschool children attending a fluoride varnish program: a cross-sectional study.

BACKGROUND: To compare the oral microflora in preschool children attending a fluoride varnish program with a reference group receiving a standard oral health program without fluoride varnish applications. A second aim was to relate the microbial composition to the caries prevalence. METHODS: Five hundred seven 3-year-old children were enrolled from a cohort of 3403 preschool children taking part in a community based oral health project. Two hundred sixty-three of them had attended caries-preventive program with semi-annual applications of a fluoride varnish since the age of 1 year (test group) while 237 had received standard preventive care (reference group). Oral samples were collected with a sterile swab and analysed with checkerboard DNA-DNA hybridization using 12 pre-determined bacterial probes. Caries and background data were collected from clinical examinations and questionnaires. RESULTS: Gram-positive streptococci (S. intermedius, S. salivarius, S. oralis) were most frequently detected and displayed the highest counts in both groups. There were no significant differences between the groups concerning prevalence of any of the selected bacterial strains except for S. oralis that occurred less frequently in the reference group. In children with caries, V. parvula were significantly more common (p < 0.05) while strains of Lactobacillus, Bifidobacterium and Neisseria were more prevalent among the caries-free children (p < 0.05). CONCLUSIONS: A 2-year community program with semi-annual fluoride varnish applications did not seem to significantly influence the oral microflora in preschool children. TRIAL REGISTRATION: www.controlled-trials.com (ISRCTN35086887) 20131216 'retrospectively registered'.

Effect of cleansing of biofilm formed on titanium discs.

OBJECTIVES: To study the combined effect of mechanical and chemical cleansing on a 4-day biofilm grown intra-orally on titanium discs with different surface characteristics. MATERIAL AND METHODS: Twenty subjects used a splint with two metal plates in the upper jaw. Each plate was placed in the premolar-molar region and carried four titanium discs with four different surface characteristics (OsseoSpeed(™), TiOblast(™), experimental and turned surface). After 4 days of biofilm growth, the discs were cleaned mechanically and chemically with saline or chlorhexidine. Following cleansing, microbial samples were obtained and analysed by culture. The titanium discs were processed for scanning electron microscope (SEM) analysis. The experiment was repeated 3 days later using delmopinol or a mixture of essential oils during cleansing. RESULTS: The combination of mechanical and chemical cleansing was ineffective in complete biofilm removal from all four titanium discs. The microbiological analysis did not reveal any statistically significant differences between surface types or between cleaning agents regarding logarithmic mean counts of CFU for specific bacteria, aerobes, anaerobes or the TVC. Aerobes were more numerous than anaerobes on all surface types. The SEM analysis disclosed that the remaining biofilm on moderately rough surfaces (OsseoSpeed(™), TiOblast(™) and experimental) was complex and firmly attached, while the biofilm on turned surface had a pattern of spread bacteria forming less clusters. CONCLUSIONS: Cleansing may call for prolonged time of chemomechanical debridement and/or more effective disinfectants to suppress biofilms on dental implant surfaces.

Virulence of Aggregatibacter actinomycetemcomitans serotypes and DGGE subtypes isolated from chronic adult periodontitis in Thailand.

A high proportion of non-serotypeable isolates of Aggregatibacter actinomycetemcomitans among Thai periodontitis cases has been previously reported. The aim of this study was to investigate the expression of leukotoxin and toxicity, cytolethal distending toxin (Cdts), and internalization and the killing effect on fibroblasts by A. actinomycetemcomitans subtypes from Thai chronic periodontitis cases. A total of 96 A. actinomycetemcomitans strains from 37 periodontitis cases, previously serotyped with PCR and subtyped with DGGE, were examined for the presence of the ltx gene and cdt genes (cdtBC), and tested for leukotoxin expression, leukotoxicity, internalization, and apoptosis of fibroblast cells. The ltx gene was present in all isolates, while 84.4% showed the cdtBC gene. Two strains with a JP2-like ltx gene with a deletion of 530 bp in the promoter region, serotyped as c, showed virulence of similar magnitude to the JP2 strain. Furthermore, a higher virulence was found in the two non-serotypeable DGGE subtypes, NS1 and NS2, compared with the serotypeable strains (serotype a-f, serotype b and d were absent). Generally, the virulence of strains obtained from deep periodontal pockets was higher than those isolated from shallow non-bleeding pockets. A. actinomycetemcomitans subtypes isolated from adult Thais with chronic periodontitis showed a highly variable virulence, leukotoxin expression, leukotoxicity, internalization and apoptosis of fibroblast, and are regulated both genetically and environmentally.

Salivary microflora and mode of delivery: a prospective case control study.

BACKGROUND: Previous cross-sectional studies have suggested that the mode of delivery can influence the composition of oral microflora. The aim of this prospective study was to compare the salivary colonization in vaginally delivered children with children delivered by Caesarian section (C-section) during their first 6 months of life. METHODS: The study group consisted of 149 consecutively enrolled infants, delivered either vaginally (n = 96) or by C-section (n = 53) that volunteered after consent of their parents. Saliva samples were collected within 2 days after birth and then after 1, 3, and 6 months. A saliva sample from the mothers was obtained 6 months after delivery. The parents were asked to complete a questionnaire on socioeconomic factors, lifestyle, and hygiene at baseline and throughout the study period. All samples were analyzed with 13 pre-determined bacterial probes using checkerboard DNA-DNA hybridization. RESULTS: The groups were balanced at baseline concerning all relevant background factors. Gram-positive streptococci (S. mitis, S. salivarius) displayed the highest counts in both groups but a greater diversity was observed in the vaginally delivered group. A. naeslundi, A. odontolytics, F. nucleatum and L. salivarius were only detected among the vaginally delivered infants. The prevalence of S. sanguinis, S. gordoni, R. denticariosa, and B. dentinum increased by age in both groups but the prevalence was significantly lower in the C-section group (p < 0.05). There was a link between the mothers and their offspring's concerning the salivary microbial profile. CONCLUSION: The microbial composition in saliva differs by the mode of delivery during the first six months of life.

Protein and bacteria binding to exposed root surfaces and the adjacent enamel surfaces in vivo.

Exposure of root surfaces due to inflammatory tissue breakdown is a clinical characteristic of periodontitis. The gingival margin may further recede during treatment. Pellicles and early dental plaque on enamel surfaces of periodontitis patients have previously been described. The binding properties of exposed root surfaces, which may affect the incorporation of proteins from especially the GCF into the enamel pellicle and thereby early dental plaque formation are largely unknown. The aim of this study was to examine if exposed root surfaces could affect pellicle and initial dental plaque formation on the enamel surface by the analysis of proteins and early adhering bacteria binding to the exposed root surfaces and to the adjacent, gingival enamel surface. Supragingival pellicle and plaque samples were taken from exposed root surfaces and the adjacent enamel surfaces in eleven surgically treated periodontitis patients. For comparison, samples were taken from enamel surfaces of teeth not in need of treatment. Additionally, subgingival bacterial samples were taken. Pellicle proteins were analysed by SDS-PAGE, immunoblotting and image analysis, and bacterial samples by culturing. Significantly more plasma proteins and bacteria were found on the exposed root surfaces than on the enamel. The depth of the gingival recessions was negatively correlated to the amount of plasma proteins in the enamel pellicle. Actinomyces spp. were most frequently found on the exposed root surfaces. The total viable counts and streptococci (%TVC) were positively correlated between subgingival samples and samples from the root surface and enamel of surgically treated teeth. A positive correlation was also found for the findings of Gram-negative anaerobes in subgingival samples and samples from the enamel surface. Our findings suggest that an exposed root surface has binding properties different from an enamel surface and could affect early biofilm formation on the adjacent enamel surface.