Sampling of periodontal pathogens by paper points: evaluation of basic parameters

Periradicular tissue fluid-derived biomarkers for apical periodontitis: An in vitro methodological and in vivo cross-sectional study

BACKGROUND

Periradicular tissue fluid (PTF) offers a source of diagnostic, prognostic and predictive biomarkers for endodontic disease.

AIMS

(1) To optimize basic parameters for PTF paper point sampling in vitro for subsequent in vivo application. (2) To compare proteomes of PTF from teeth with normal apical tissues (NAT) and asymptomatic apical periodontitis (AAP) using high-throughput panels.

METHODOLOGY

(1) To assess volume absorbance, paper points (n = 20) of multiple brands, sizes and sampling durations were inserted into PBS/1%BSA at several depths. Wetted lengths (mm) were measured against standard curves to determine volume absorbance (μL). To assess analyte recovery, paper points (n = 6) loaded with 2 μL recombinant IL-1β (15.6 ng/mL) were eluted into 250 μL: (i) PBS; (ii) PBS/1% BSA; (iii) PBS/0.1% Tween20; (iv) PBS/0.25 M NaCl. These then underwent: (i) vortexing; (ii) vortexing/centrifugation; (iii) centrifugation; (iv) incubation/vortexing/centrifugation. Sandwich-ELISAs determined analyte recovery (%) against positive controls. (2) Using optimized protocols, PTF was retrieved from permanent teeth with NAT or AAP after accessing root canals. Samples, normalized to total fluid volume (TFV), were analysed to determine proteomic profiles (pg/TFV) of NAT and AAP via O-link Target-48 panel. Correlations between AAP and diagnostic accuracy were explored using principal-component analysis (PCA) and area under receive-operating-characteristic curves (AUC [95% CI]), respectively. Statistical comparisons were made using Mann-Whitney U, anova and post hoc Bonferonni tests (α < .01).

RESULTS

(1) UnoDent's 'Classic' points facilitated maximum volume absorbance (p < .05), with no significant differences after 60 s (1.6 μL [1.30-1.73]), 1 mm depth and up to 40/0.02 (2.2 μL [1.98-2.20]). For elution, vortexing (89.3%) and PBS/1% BSA (86.9%) yielded the largest IL-1β recovery (p < .05). (2) 41 (NAT: 13; AAP: 31) PTF samples proceeded to analysis. The panel detected 18 analytes (CCL-2, -3, -4; CSF-1; CXCL-8, -9; HGF; IL-1β, -6, -17A, -18; MMP-1, -12; OLR-1; OSM; TNFSF-10, -12; VEGF-A) in ≥75% of AAP samples at statistically higher concentrations (p < .01). CXCL-8, IL-1β, OLR-1, OSM and TNFSF-12 were strongly correlated to AAP. 'Excellent' diagnostic performance was observed for TNFSF-12 (AUC: 0.94 [95% CI: 0.86-1.00]) and the PCA-derived cluster (AUC: 0.96 [95% CI: 0.89-1.00]).

CONCLUSIONS

Optimized PTF sampling parameters were identified in this study. When applied clinically, high-throughput proteomic analyses revealed complex interconnected networks of potential biomarkers. TNFSF-12 discriminated periradicular disease from health the greatest; however, clustering analytes further improved diagnostic accuracy. Additional independent investigations are required to validate these findings.

A pattern of microbiological colonization of orthodontic miniscrew implants

INTRODUCTION

Current orthodontic literature reveals a lack of studies on bacterial colonization of orthodontic miniscrew implants (MSI) and their role in the stability of MSI. This study aimed to determine the pattern of microbiological colonization of miniscrew implants in 2 major age groups, to compare it with the microbial flora of gingival sulci in the same group of patients and to compare microbial flora in successful and failed miniscrews.

METHODS

The study involved 102 MSI placed in 32 orthodontic subjects in 2 age groups: (1) aged ≤14 years and (2) aged >14 years. Gingival and peri-mini implant crevicular fluid samples were collected using sterile paper points (International Organization for Standardization no. 35) >3 months and processed by conventional microbiologic culture and biochemical techniques. A microbiologist characterized and identified the bacteria, and the results were subjected to statistical analysis.

RESULTS

Initial colonization was reported within 24 hours, with Streptococci being the dominant colonizer. The relative proportion of anaerobic bacteria over aerobic bacteria increased over time in peri-mini implant crevicular fluid. Group 1 had greater Citrobacter (P = 0.036) and Parvimonas micra (P = 0.016) colonizing MSI than group 2. Failed MSI showed a significantly higher presence of Parvimonas micra (P = 0.008) in group 1 and Staphylococci (P = 0.008), Enterococci (P = 0.011), and Parvimonas micra (P <0.001) in group 2.

CONCLUSIONS

Microbial colonization around MSI is established within 24 hours. Compared to gingival crevicular fluid, peri-mini implant crevicular fluid is colonized by a higher proportion of Staphylococci, facultative enteric commensals and anaerobic cocci. The failed miniscrews showed a higher proportion of Staphylococci, Enterobacter, and Parvimonas micra, suggesting their possible role in the stability of MSI. The bacterial profile of MSI varies with age.

Smoking negatively impacts the clinical, microbiological, and immunological treatment response of young adults with Grade C periodontitis

OBJECTIVE

This study aimed to investigate the influence of smoking on clinical, microbiological and immunological parameters in young adult with stage III-IV Grade C periodontitis after full-mouth ultrasonic debridement (FMUD) associated with Amoxicillin and Metronidazole (AMX + MTZ), comparing smokers (PerioC-Y-Smk) with non-smokers (PerioC-Y-NSmk).

MATERIALS AND METHODS

Fifteen PerioC-Y-NSmk and 14 PerioC-Y-Smk patients underwent FMUD associated with AMX + MTZ for 10 days. All parameters were collected at baseline and 3 and 6 months after treatment. Plaque index (PI), bleeding on probing (BoP), probing depth (PD), clinical attachment level (CAL)- the primary variable-, and gingival recession (GR) were clinically assessed. The impact of PI on CAL change at 6-month was verified by a regression analysis. Samples of the subgingival biofilm was collected for detection of levels of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), Porphyromonas gingivalis (P.gingivalis), Tannerella forsythia (T. forsythia), and Fusobacterium nucleatum ssp (F. nucleatum), and were analyzed by real-time qPCR; gingival crevicular fluid was collected for detection of levels of interleukin (IL)-1β, IL-4, IL-6, IL-10, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, which were analyzed using an enzyme immunoassay.

RESULTS

PerioC-Y-Smk had significantly higher PI, BOP, and GR at baseline compared to non-smokers (p < .05). PerioC-Y-Smk presented higher PD, CAL, and GR at 3 and 6 months (p < .05) compared with PerioC-Y-NSmk in the same periods; PI negatively affected CAL gain in PerioC-Y-NSmk at 6-month follow-up (p = .052) and did not impact on clinical response in PerioC-Y-Smk (p = .882). Lower levels of IFN-γ, IL1-β, and IL-4 were observed at 3 months in the PerioC-Y-NSmk (p < .05) compared with PerioC-Y-Smk. Lower proportions of P. gingivalis were observed in PerioC-Y-NSmk at baseline and at 3 months (p < .05) and lower proportions of F. nucleatum were observed at 6 months, in the PerioC-Y-NSmk (p < .05).

CONCLUSIONS

PerioC-Y-Smk presents an unfavorable clinical, microbiological, and immunological response after 3 and 6 months after FMUD associated with AMX + MTZ.

CLINICAL RELEVANCE

Smoking worsens periodontal condition of young treated adults presenting stage III/IV Grade C periodontitis.

Oxidative/anti-oxidative effects of colloidal silver ions and chlorhexidine in saliva and gingival fluid of periodontal patients

Background/Aim. Chronic periodontitis is an inflammatory disease. Oxidative stress is an important factor in periodontitis progress, hence examining the antioxidative properties of antiseptics, such as chlorhexidine (CHX) and silver ions solution (SSI), is a beneficial biomarker in estimating the recovery of tissue impairment during periodontal disease treatment. Methods. This clinical trial was conducted on the control group referred to healthy volunteers and individuals with periodontal disease, divided into two subgroups: before and after applying antiseptic treatments (CHX or SSI). Measurements of oxidative/antioxidative parameters were addressed to determine thiobarbituric acid products (TBARS) concentration and total superoxide dismutase (tSOD) activity in saliva and gingival crevicular fluid (GCF) of periodontal patients. Results. TBARS concentration was increased in saliva before the CHX treatment compared to the periodontal group after the CHX treatment, as well as before both CHX and SSI antiseptic treatment in CGF, compared to controls and periodontal groups after the treatment. Patients before SSI treatment had increased tSOD activity in saliva compared to the control group treated with SSI, as well as compared to patients after the SSI treatment. Additionally, tSOD activity was increased in GCF in patients with periodontitis before antiseptic treatment (CHX, SSI) compared to the control or the group of patients after the appropriate treatment. Conclusion. Our results revealed elevated lipid peroxidation in CGF, which reflected the promotion of oxidative stress during periodontal inflammation. The study suggests that antiseptics with antioxidant properties may reduce tissue damage initiated by periodontal disease. Moreover, the determination of oxidative/antioxidative parameters can be important for diagnosing, monitoring, and prognosis of the clinical state of periodontal patients.

The Varied Proportion of Filifactor alocis in Periodontal Health and Disease in the South Indian Subpopulation

BACKGROUND AND AIM

The periodontal microbiome being complex, this study was aimed to detect and quantify the prevalence of Filifactor alocis in various stages of periodontitis and to evaluate its prospect as a diagnostic marker for periodontal disease.

SETTINGS AND DESIGN

Sixty subjects were selected (20 healthy controls, 20 with chronic periodontitis, and 20 with aggressive periodontitis) for the study.

MATERIALS AND METHODS

Clinical parameters probing depth and the level of clinical attachment was recorded, subgingival plaque samples were collected. The F. alocis 16srDNA was cloned, sequenced, and used as the standard for real-time quantification of bacterial load using SYBR green chemistry.

STATISTICAL ANALYSIS

Clinical, microbiological, and quantitative polymerase chain reaction (PCR) data were analyzed using ANOVA and Pearson's coefficient correlation.

RESULTS

(a) Real-time PCR analysis showed the highest average F. alocis count in chronic periodontitis subjects (32,409.85), which was followed by count in healthy controls (3046.15) and the least count in aggressive periodontitis subjects (939.84). The bacterial count was statistically significant at P = 0.005. (b) An intra-group comparison reveals that there was a statistically significant increase in the bacterial count with age and mean probing pocket depth at P = 0.0005.

CONCLUSION

F. alocis population in aggressive periodontitis was lower compared to chronic periodontitis and healthy controls. The F. alocis population surge in healthy controls may be due to geographical variations and the ethnicity of the subjects. A higher population of F. alocis in chronic periodontitis proves its high pathogenic potential to invade the host tissues to aid in further periodontal destruction.

Clinical influence of calcium hydroxide intracanal medications on matrix metalloproteinases and tissue inhibitors of metalloproteinases in apical periodontitis

OBJECTIVES

This study investigated the influence of calcium hydroxide intracanal medications on the levels of metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in apical periodontitis (AP).

MATERIALS AND METHODS

Twenty primarily infected root canals with AP were randomly divided into two groups: Ca(OH)₂ + sterile saline solution (SSL) group and Ca(OH)₂ + 2% chlorhexidine gel (CHX gel) group. We collected samples from the periradicular tissue fluid (PTF) before (s1) and after 14 days of intracanal medication (s2). MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were measured by ELISA assay.

RESULTS

MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were detected in all PTF samples at s1 and s2 (20/20). At s1, MMP-2 and MMP-9 were detected at higher levels than MMP-1 (p < .05). Higher levels of TIMP-1 than TIMP-2 were found in AP (p < .05). Additionally, we detected higher MMP-1, MMP-2, and MMP-9 over TIMP-1 and TIMP-2 levels in AP (p < .05). At s2, Ca(OH)₂ + SSL was as effective as Ca(OH)₂ + 2% CHX gel in lowering the levels of MMP-1, MMP-2, and MMP-9 after 14 days of intracanal medication, with no significant difference between them (p > .05). Both Ca(OH) ₂ intracanal medications had no significant impact on the levels of TIMP-1 and TIMP-2 (both p > .05). At s2, TIMP-1 levels were higher than TIMP-2 (p < .05). Moreover, there were positive correlations between the levels of MMP-1 and TIMP-1 and MMP-1 and TIMP-2 (p < .05).

CONCLUSIONS

Calcium hydroxide medications effectively lowered the levels of MMP-1, MMP-2, and MMP-9 in periapical tissues after 14 days of treatment, with no difference between them. Moreover, the calcium hydroxide intracanal medications tested here had no impact in TIMP-1 and TIMP-2 in periapical tissues.

CLINICAL RELEVANCE

MMPs and TIMPs play an essential role in the degradation of the extracellular matrix. The imbalance MMPs and TIMPs can cause periapical tissue destruction. Therefore, the reestablishment of the balance between activated MMPs and TIMPs with root canal therapy is essential to restore tissue homeostasis.

Increasing Reproducibility in Oral Microbiome Research

Evidence on the role of the oral microbiome in health and disease is changing the way we understand, diagnose, and treat ailments. Numerous studies on diseases affecting the oral cavity have revealed a large amount of data that is invaluable for the advancements in diagnosing and treating these diseases. However, the clinical translation of most of these exploratory data is stalled by variable methodology between studies and non-uniform reporting of the data.Understanding the key areas that are gateways to bias in microbiome studies is imperative to overcome this challenge faced by oral microbiome research. Bias can be multifactorial and may be introduced in a microbiome research study during the formulation of the study design, sample collection and storage, or the sample processing protocols before sequencing. This chapter summarizes the recommendations from literature to eliminate bias in the microbiome research studies and to ensure the reproducibility of the microbiome research data.

Detection of Epstein-Barr Virus in Periodontitis: A Review of Methodological Approaches

Periodontitis, an inflammatory condition that affects the structures surrounding the tooth eventually leading to tooth loss, is one of the two biggest threats to oral health. Beyond oral health, it is associated with systemic diseases and even with cancer risk. Obviously, periodontitis represents a major global health problem with significant social and economic impact. Recently, a new paradigm was proposed in the etiopathogenesis of periodontitis involving a herpesviral–bacterial combination to promote long-term chronic inflammatory disease. Periodontitis as a risk factor for other systemic diseases can also be better explained based on viral–bacterial etiology. Significant efforts have brought numerous advances in revealing the links between periodontitis and Epstein–Barr virus (EBV), a gamma herpesvirus ubiquitous in the adult human population. The strong evidence from these studies may contribute to the advancement of periodontitis research and the ultimate control of the disease. Advancing the periodontitis research will require implementing suitable methods to establish EBV involvement in periodontitis. This review evaluates and summarizes the existing methods that allow the detection and diagnosis of EBV in periodontitis (also applicable in a more general way to other EBV-related diseases), and discusses the feasibility of the application of innovative emerging technologies.

Clinical influence of calcium hydroxide and N-acetylcysteine on the levels of resolvins E1 and D2 in apical periodontitis

AIM

To investigate the presence of resolvins E1 (RvE1) and D2 (RvD2) in teeth with primary endodontic infections and apical periodontitis, and to assess the influence of calcium hydroxide medication [Ca(OH)₂ ], in association with 2% chlorhexidine gel (2% CHX gel), and N-acetylcysteine (NAC) on the levels of RvE1 and RvD2 in periapical tissues.

METHODOLOGY

Thirty-six single-rooted teeth with primary endodontic infections and apical periodontitis were selected and randomly divided into three groups according to the medication: [Ca(OH)₂ ] + saline solution (SSL) [Ca(OH)₂  + SSL group] (n = 12), Ca(OH)₂  + 2% chlorhexidine gel [Ca(OH)₂  + 2% CHX gel group] (n = 12) and NAC [NAC group] (n = 12). Samples were collected from the periapical interstitial fluid at two different sampling times: before (S1) and after 14 days of intracanal medications (S2). Resolvins were measured using the enzyme-linked immunosorbent assay. Data were analysed using paired t-test, Wilcoxon test and Kruskal-Wallis test, followed by Dunn's post hoc test; all statistical tests were performed at a significance level of 5%.

RESULTS

RvE1 and RvD2 were detected in 100% of the samples (36/36) at S1 and S2. Ca(OH)₂ medication did not increase the levels of RvE1 or RvD2 (both P > 0.05); however, NAC significantly increased the levels of RvE1 and RvD2 after 14 days of treatment (P < 0.05).

CONCLUSIONS

RvE1 and RvD2 were detected in periapical tissues from teeth with root canal infections. Moreover, calcium hydroxide medication did not increase the levels of resolvins in apical periodontitis. In contrast, the use of NAC intracanal medication significantly increased the levels of RvE1 and RvD2 after 14 days of treatment.

Challenges of next-generation sequencing targeting anaerobes

Next-generation sequencing allows for investigating the composition of microbiomes that are associated with infection (clinical microbiology) or dysbiosis (microbial ecology). The most commonly applied short-read sequencing technologies are Illumina MiSeq/HiSeq and Ion Torrent PGM, however, other platforms that generate long-reads are under way and optimized. A pre-condition for representative results is an appropriate method for contamination-free collection, homogenization, storage of specimens and a subsequent efficient DNA extraction protocol. As some of the anaerobes such as Clostridia or anaerobe Archaea are robust while others of the same environment, such as spirochetes, possess a very thin cell wall, a chemico-mechanical lysing strategy is recommended but with some precautions to avoid DNA-sheering and overheating. For amplicon sequencing, the Silva-TestPrime online tool helps to find the optimal 16S directed primers for individual studies. For metagenome profiling, the classifier tool has to be selected with helpful decision trees available but a combination based on different strategies seems to be indispensable. Further development of both hard- and software is needed before microbiome results become free of a substantial technology-dependent bias.

Ozone application as adjunctive therapy in chronic periodontitis: Clinical, microbiological and biochemical aspects

Background/purpose

The application of ozone as an adjunctive treatment represents a new approach in the management of chronic periodontitis. The purpose of this study was to evaluate the clinical, biochemical and microbiological efficacy of ozone treatment as an adjunct to scaling and root planing (SRP) in generalized chronic periodontitis (GCP) patients.

Materials and methods

Eighteen patients (9 males and 9 females; aged from 28 to 47 years, mean age of 40 ± 6.51 years) with GCP were recruited in the study. In a split mouth design, two quadrants in each patient were randomly allocated to SRP-alone or SRP-ozone therapy (SRP + OT) groups by coin toss method. Subgingival plaque and gingival crevicular fluid (GCF) samples were collected at baseline, following 1st and 3rd months. The clinical parameters were monitored at baseline and after 3 months. Microbiological parameters were analyzed by quantitative-PCR and GCF biomarkers were determined by ELISA. Results were analyzed statistically.

Results

Statistically significant improvements in all clinical parameters were accompanied by a reduction in microbiological and biochemical parameters in both treatment groups. SRP treatment resulted in a significant reduction of Porphyromonas gingivalis (Pg) at 1st month and Tannerella forsythia (Tf) and Prevotella intermedia (Pi) at 3 months. Following SRP treatment the interleukin (IL)-8 levels were significantly reduced at month 1. There were no significant differences between two treatments for any of the parameters.

Conclusion

Within the limitations of this study, adjunctive ozone therapy did not provide additional benefits to clinical, microbiological and biochemical parameters over SRP in chronic periodontitis patients.

Sampling Modification Effects in the Subgingival Microbiome Profile of Healthy Children

Background: Oral microbiota are considered major players in the development of periodontal diseases. Thorough knowledge of intact subgingival microbiomes is required to elucidate microbial shifts from health to disease.

Aims: This comparative study investigated the subgingival microbiome of healthy children, possible inter- and intra-individual effects of modified sampling, and basic comparability of subgingival microprints.

Methods: In five 10-year-old children, biofilm was collected from the upper first premolars and first molars using sterilized, UV-treated paper-points inserted into the subgingival sulcus at eight sites. After supragingival cleaning using an electric toothbrush and water, sampling was performed, firstly, excluding (Mode A) and, secondly, including (Mode B) cleansing with sterile cotton pellets. DNA was extracted from the pooled samples, and primers targeting 16S rRNA hypervariable regions V5 and V6 were used for 454-pyrosequencing. Wilcoxon signed rank test and t-test were applied to compare sampling modes. Principal coordinate analysis (PCoA) and average agglomerative hierarchical clustering were calculated with unweighted UniFrac distance matrices. Sample grouping was tested with permutational MANOVA (Adonis).

Results: Data filtering and quality control yielded 67,218 sequences with an average sequence length of 243bp (SD 6.52; range 231–255). Actinobacteria (2.8–24.6%), Bacteroidetes (9.2–25.1%), Proteobacteria (4.9–50.6%), Firmicutes (16.5–57.4%), and Fusobacteria (2.2–17.1%) were the five major phyla found in all samples. Differences in microbial abundances between sampling modes were not evident. High sampling numbers are needed to achieve significance for rare bacterial phyla. Samples taken from one individual using different sampling modes were more similar to each other than to other individuals' samples. PCoA and hierarchical clustering showed a grouping of the paired samples. Permutational MANOVA did not reveal sample grouping by sampling modes (p = 0.914 by R² = 0.09).

Conclusion: A slight modification of sampling mode has minor effects corresponding to a natural variability in the microbiome profiles of healthy children. The inter-individual variability in subgingival microprints is greater than intra-individual differences. Statistical analyses of microbial populations should consider this baseline variability and move beyond mere quantification with input from visual analytics. Comparative results are difficult to summarize as methods for studying huge datasets are still evolving. Advanced approaches are needed for sample size calculations in clinical settings.

Detection of subgingival periodontal pathogens--comparison of two sampling strategies

OBJECTIVE

The aim of the study is to compare detection frequency of periodontal pathogens in patients with aggressive/severe chronic periodontitis using pooled plaque samples from the deepest pockets per quadrant/per sextant.

METHODS

In 100 patients with aggressive/chronic periodontitis, subgingival plaque was sampled from the deepest pockets per quadrant (MT4) and per sextant (MT6). Plaque samples were taken using two sterile paper points simultaneously. One paper point from each pocket was pooled with the three other paper points of the pockets (MT4). Subsequently, the remaining four paper points were pooled with two paper points from the deepest pockets from the two remaining sextants (MT6). The content of each vial was analyzed with nucleic-acid based methods for Aggregatibacter actinomycetemcomitans, Tannerella forsythia, Porphyromonas gingivalis, Treponema denticola, Prevotella intermedia, Parvimonas micra, Fusobacterium nucleatum, Campylobacter rectus, Eubacterium nodatum, Eikenella corrodens, and Capnocytophaga sp.

RESULTS

The detection frequency of A. actinomycetemcomitans (MT4/MT6) at 22/24 %, T. forsythia at 93/96 %, P. gingivalis at 78/79 %, T. denticola at 88/90 %, P. intermedia at 40/46 %, P. micra at 75/79 %, F. nucleatum at both 99 %, C. rectus at 84/89 %, E. nodatum at 62/65 %, E. corrodens at 80/87 %, and Capnocytophaga sp. at 49/58 % was higher with MT6 than with MT4. None of these differences were statistically significant.

CONCLUSION

The detection frequency of the investigated periopathogens was statistically insignificant higher with the sampling method MT6 compared with MT4.

CLINICAL RELEVANCE

In daily dental practice, the plaque sampling of the deepest pockets per quadrant seems to be sufficient.

Antimicrobial photodynamic effect to treat residual pockets in periodontal patients: a randomized controlled clinical trial

AIM

A randomized controlled clinical trial was designed to evaluate the efficacy of the photodynamic therapy (PDT) in the treatment of residual pockets of chronic periodontitis patients.

MATERIAL AND METHODS

Thirty-four patients with at least four residual periodontal pockets undergoing maintenance care were included and randomly assigned to test group (PDT, n = 18) or control group (sham procedure, n = 16). The intervention was performed at baseline, 3, 6 and 12 months. Clinical parameters such as pocket probing depth (PPD), clinical attachment level (CAL), bleeding on probing (BoP) and plaque index (PI) were measured before intervention and after 3, 6 and 12 months. Subgingival samples were obtained at baseline, and after 7 days, 3, 6 and 12 months to quantify Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia by real-time polimerase chain reaction (PCR).

RESULTS

All clinical variables showed significant improvement during the study, but there was no significant difference between test and control groups. The microbiological analyses showed no differences between groups at any time during the study.

CONCLUSION

Within the limits of this clinical trial and considering the laser and photosensitizer protocol used, PDT failed to demonstrate additional clinical and bacteriological benefits in residual pockets treatment.

Microbial changes in subgingival plaque and polymicrobial intracellular flora in buccal cells after fixed orthodontic appliance therapy: a preliminary study

The oral ecosystem is strictly related to a balance maintained by specific niches recognized as sites, where oral bacteria can metabolize avoiding the immune system response. The oral bacteria species that colonize the ecological niches vary during fixed orthodontic treatment, with a prevalence of periodontal bacterial species. Qualitative analysis of five periodontal pathogens was used to investigate the microbial colonization rate in the crevice and buccal epithelial cells. The presence of inadequate oral hygiene was considered as a modulation variable for microbial colonization. Statistical analysis was performed by Fisher's exact test, ANOVA, and Pearson correlation. A P value lower than 0.05 was assumed as statistically significant. Tannerella forsythia was the only periodontal pathogen detected with a statistically admissible frequency. The positivity for Tannerella forsythia was correlated to sampling time and oral hygiene motivation. In buccal epithelial cells, both factors contributed to microbial decrease (P < 0.05), whereas, in crevice, oral hygiene motivation promoted a decrease in the microbial colonization rate (P < 0.05). According to microbiological findings, it is possible to identify how correct motivation for oral hygiene is more than enough to modulate or to avoid an upset of the oral ecosystem balance in early stages of orthodontic treatment.

Microbial analysis of subgingival plaque samples compared to that of whole saliva in patients with periodontitis

BACKGROUND

The detection of special bacterial species in patients with periodontitis is considered to be useful for clinical diagnosis and treatment. The collection of subgingival plaque samples is the common way for the determination of periodontopathic bacteria. However, recently, salivary analysis has been discussed as an advantageous future diagnostic method for periodontitis because it offers simple quantitative sampling and the possibility to assess various bacteria. The aim of this cross-sectional study is to investigate whether there is a correlation between the results of different bacterial species in saliva and subgingival plaque samples from individuals with aggressive periodontitis (AgP) and chronic periodontitis (CP).

METHODS

Whole saliva and subgingival plaque samples from the deepest pocket of each quadrant were collected from 43 patients with CP and 33 patients with AgP. Twenty different bacterial species from both samplings were determined by the 16S ribosomal RNA-based polymerase chain reaction with microarray technique.

RESULTS

All bacterial species were detected in salivary and subgingival plaque samples. For Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, as well as Actinomyces viscosus, Campylobacter rectus/showae, Prevotella intermedia, Parvimonas micra, Eubacterium nodatum, and Campylobacter gracilis, a significant positive correlation between salivary and subgingival plaque samples was detected in patients with both types of periodontitis. There were no significant differences in bacteria in salivary and subgingival plaque samples between AgP and CP.

CONCLUSION

Salivary analysis might be discussed as a potential alternative to subgingival plaque sampling for microbiologic analysis in both AgP and CP.

Investigation of the effect of type 2 diabetes mellitus on subgingival plaque microbiota by high-throughput 16S rDNA pyrosequencing

Diabetes mellitus is a major risk factor for chronic periodontitis. We investigated the effects of type 2 diabetes on the subgingival plaque bacterial composition by applying culture-independent 16S rDNA sequencing to periodontal bacteria isolated from four groups of volunteers: non-diabetic subjects without periodontitis, non-diabetic subjects with periodontitis, type 2 diabetic patients without periodontitis, and type 2 diabetic patients with periodontitis. A total of 71,373 high-quality sequences were produced from the V1-V3 region of 16S rDNA genes by 454 pyrosequencing. Those 16S rDNA sequences were classified into 16 phyla, 27 classes, 48 orders, 85 families, 126 genera, and 1141 species-level OTUs. Comparing periodontally healthy samples with periodontitis samples identified 20 health-associated and 15 periodontitis-associated OTUs. In the subjects with healthy periodontium, the abundances of three genera (Prevotella, Pseudomonas, and Tannerella) and nine OTUs were significantly different between diabetic patients and their non-diabetic counterparts. In the subjects carrying periodontitis, the abundances of three phyla (Actinobacteria, Proteobacteria, and Bacteriodetes), two genera (Actinomyces and Aggregatibacter), and six OTUs were also significantly different between diabetics and non-diabetics. Our results show that type 2 diabetes mellitus could alter the bacterial composition in the subgingival plaque.

Proteomic analysis of gingival crevicular fluid for discovery of novel periodontal disease markers

The protein composition of gingival crevicular fluid (GCF) may reflect the pathophysiology of periodontal diseases. A standard GCF proteomic pattern of healthy individuals would serve as a reference to identify biomarkers of periodontal diseases by proteome analyses. However, protein profiles of GCF obtained from apparently healthy individuals have not been well explored. As a step toward detection of proteomic biomarkers for periodontal diseases, we applied both gel-based and gel-free methods to analyze GCF obtained from healthy subjects as compared with supragingival saliva. To ensure optimized protein extraction from GCF, a novel protocol was developed. The proteins in GCF were extracted with high yield by urea buffer combined with ultrafiltration and the intensity of spots with supragingival saliva and GCF was compared using agarose two-dimensional electrophoresis. Eight protein spots were found to be significantly more intense in GCF. They included superoxide dismutase 1 (SOD1), apolipoprotein A-I (ApoA-I), and dermcidin (DCD). Moreover, GCF proteins from healthy subjects were broken down into small peptide fragments and then analyzed directly by LC-MS/MS analysis. A total of 327 proteins including ApoA-I, SOD1, and DCD were identified in GCF. These results may serve as reference for future proteomic studies searching for GCF biomarkers of periodontal diseases.

Measurement of tear production in black-tufted marmosets (Callithrix penicillata) using three different methods: modified Schirmer's I, phenol red thread and standardized endodontic absorbent paper points

OBJECTIVE

To report normal tear production of healthy adult black-tufted marmosets and propose a novel alternative for the measurement of the aqueous portion of tear production in animals with small eyes.

ANIMAL STUDIED

Black-tufted marmosets (Callithrix penicillata).

PROCEDURES

Tear production of 19 animals was evaluated by the following methods: modified Schirmer's I, phenol red thread and the novel use of standardized endodontic absorbent paper points. These methods and results were compared. Additionally, blink frequency and palpebral fissure length were measured.

RESULTS

Modified Schirmer's test I, mean = -0.46 ± 3.41 mm/min; Phenol red thread, mean = 13.27 ± 5.41 mm/15 s.; Standardized endodontic paper points, size 30, mean = 9.32 ± 3.09 mm/min; Mean palpebral fissure length = 7.83 ± 0.72 mm. Blink frequency, mean = 20.27 ± 5.92/5 min.

CONCLUSIONS

Normal parameters for blink frequency, palpebral fissure length and tear production measurement are presented. The palpebral fissure of black-tufted marmoset is very small and tear production is one of the lowest reported for all animal species. A novel and practical alternative for tear production measurement using standardized endodontic absorbent paper points is presented and is indicated for animals with small eyes.

Profiling of subgingival plaque biofilm microflora from periodontally healthy subjects and from subjects with periodontitis using quantitative real-time PCR

BACKGROUND AND OBJECTIVE

Qualitative and quantitative changes of the subgingival plaque biofilm microflora in periodontal pockets are thought to be associated with the development and progression of periodontitis. The aims of the present study were to quantify the proportions of nine periodontitis-associated bacterial species and four Streptococcus species in subgingival plaque, and to evaluate their relationship with periodontitis quantitatively.

MATERIAL AND METHODS

Subgingival plaque samples were obtained from 12 periodontally healthy subjects and from 28 patients with periodontitis. The amounts of total and target bacteria were measured by quantitative real-time PCR using universal and species-specific primers, respectively.

RESULTS

The proportion of total obligate anaerobes was found to be higher in subjects with periodontitis than in periodontally healthy subjects (p < 0.05). Among obligate anaerobes, Tannerella forsythia (2.04 +/- 5.27%, p < 0.05), Porphyromonas gingivalis (0.54 +/- 1.41%) and Eubacterium saphenum (0.30 +/- 0.96%) were detected at high proportions in subjects with periodontitis, but not in periodontally healthy subjects. By contrast, the proportion of total streptococci was lower in subjects with periodontitis (p < 0.05). Specifically, the proportion of T. forsythia, P. gingivalis or E. saphenum increased (>or= 2.78%) and the proportion of Streptococcus species decreased to virtually undetectable levels, in subjects with periodontitis.

CONCLUSION

Obligate anaerobes, including T. forthysia, P. gingivalis and E. saphenum, were identified predominantly in microflora from subjects with periodontitis, whereas Streptococcus species were identified predominantly in microflora from periodontally healthy subjects, suggesting a change in the subgingival environment that resulted in conditions more suitable for the survival of obligate anaerobes. The proportion of these obligate anaerobes in the subgingival plaque of subjects with periodontitis appears to be associated with the status of human periodontitis.

New methods for selective isolation of bacterial DNA from human clinical specimens

Separation of bacterial DNA from human DNA in clinical samples may have an important impact on downstream applications, involving microbial diagnostic systems. We evaluated two commercially available reagents (MolYsis), Molzym GmbH & Co. KG, Bremen and Pureprove, SIRS-Lab GmbH, Jena, both Germany) for their potential to isolate and purify bacterial DNA from human DNA. We chose oral samples, which usually contain very high amounts of both human and bacterial cells. Three different DNA preparations each were made from eight caries and eight periodontal specimens using the two reagents above and a conventional DNA extraction strategy as reference. Based on target-specific real-time-quantitative PCR assays we compared the reduction of human DNA versus loss of bacterial DNA. Human DNA was monitored by targeting the beta-2-microglobulin gene, while bacteria were monitored by targeting 16S rDNA (total bacteria and Porphyromonas gingivalis) or the glycosyltransferase gene (Streptococcus mutans). We found that in most cases at least 90% of human DNA could successfully be removed, with complete removal in eight of 16 cases using MolYsis, and two (of 16) cases using Pureprove. Conversely, detection of bacterial DNA was possible in all cases with a recovery rate generally ranging from 35% to 50%. In conclusion, both strategies have the potential to reduce background interference from the host DNA which may be of remarkable value for nucleic-acid based microbial diagnostic systems.

Recovery of putative pathogens from paper point sampling at different depths of periodontal lesions

Background

The aim of this study was to compare the recovery of three putative periodontal pathogens from periodontal lesions in samples using paper points inserted to different depths of the lesions.

Methods

Twenty 6–8 mm deep periodontal lesions with bleeding on probing were studied. Microbial samples were obtained using paper points inserted to three different depths of the lesions: orifice of lesion; 2 mm into the lesion; and to the base of lesion. Culturing was used for recovery and identification of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia.

Results

The recovery of each of the three putative periodontal pathogens was similar following sampling at the various depths of the lesions.

Conclusions

The findings may be explained by the fact that the paper points become saturated as they pass through the orifice of the lesion. Absorption of microorganisms will therefore primarily occur at the orifice. It is also conceivable that the pathogens may be present in similar proportions throughout the various depths of the periodontal lesions.

Photodynamic therapy for root canals infected with Enterococcus faecalis

OBJECTIVE

The aim of this study was to investigate the effects of photodynamic therapy (PDT) on endodontic pathogens by evaluating the decrease in numbers of Enterococcus faecalis colonies in the canals of extracted human teeth.

BACKGROUND DATA

Failure in endodontics is usually related to inadequate cleaning and disinfection of the root canal system. This is due to the establishment of microorganisms in areas where the instruments and chemical agents used during root canal preparation cannot eliminate them. PDT is a complementary therapeutic method that could be used to eliminate these remaining bacteria. PDT is a process in which radiation acts on a dye that is applied to the target organism, resulting in bacterial death.

MATERIALS AND METHODS

Forty-six uniradicular teeth had their canals contaminated with bacteria and were incubated for 48 h at 35 degrees C. After that, the teeth were divided into a control group (CG) and a test group (TG). The 23 CG teeth did not undergo any intervention, whereas in the TG the teeth received a solution of 0.0125% toluidine blue for 5 min followed by irradiation using a 50-mW diode laser (Ga-Al-As) at a wavelength of 660 nm. Bacterial samples were taken before and after irradiation. In each of the samples, the number of colony-forming units (CFU) was counted.

RESULTS

The mean decrease in CFU was 99.9% in the TG, whereas in the CG an increase of 2.6% was observed.

CONCLUSION

PDT was effective as a bactericidal agent in Enterococcus faecalis-contaminated root canals.

The reproducibility of curet sampling of subgingival biofilms

BACKGROUND

Because few studies have examined the critical issue of sampling reproducibility, the purpose of the present study was to examine the reproducibility of curet sampling of subgingival biofilms.

METHODS

Seven subgingival biofilm samples were taken successively, using a curet, from each of 80 sites and individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. One healthy site was sampled in each of 20 periodontally healthy subjects, and one sulcus/pocket of < or =3, 4 to 5, and > or =6 mm was sampled in each of 20 subjects with chronic periodontitis. The significance of differences in counts and proportions of individual species at the seven successive samplings for each probing depth (PD) category was determined using the Kruskal-Wallis test. The reproducibility of species proportions at each PD category was measured using the coefficient of variation (CV), and the consistency of microbial profiles across samples was examined using the minimum similarity coefficient.

RESULTS

There was no significant difference in the mean proportions of the 40 test species in the seven successive samples in each of the four PD categories. The median CV for individual species in the same site was 0.79 (95% confidence interval [CI]: 0.76 to 0.82) compared to 1.76 (95% CI: 1.69 to 1.82) in samples from different sites. The within-site mean minimum similarity coefficient (+/- SEM) was 51.2% +/- 2.2%, and it was 27.9% +/- 0.3% between sites.

CONCLUSION

The proportions of species remained consistent in successive curet samples, indicating that the use of curets provided a reliable and reproducible method to obtain subgingival samples.

Effects of fixed orthodontic appliances on subgingival microflora

OBJECTIVES

Fixed orthodontic appliances cause plaque accumulation around bands and brackets. Since the microbiological composition of dental plaque is closely connected to periodontal tissue health, the aim of this study was to determine the effects of fixed orthodontic appliances on subgingival microflora and periodontal status.

METHODS

This prospective study was carried out on 32 adolescents scheduled for fixed orthodontic treatment. Subgingival dental plaque samples and periodontal records (pocket probing depth and clinical attachment level) were obtained in four recording times: before bonding of fixed appliances (T0), 1 (T1), 3 (T2) and 6 (T3) months after the beginning of orthodontic therapy, in order to detect the changes in periodontopathic anaerobe microbial flora and its effects on periodontal status.

RESULTS

The values of pocket probing depth, total number of microorganisms and number of patients with positive findings of Prevotella intermedia and other periodontopathic anaerobes increased from T0 to the maximum obtained in T2 recording time. Both clinical and microbiological values decreased 6 months after the beginning of orthodontic therapy.

CONCLUSIONS

The therapy with fixed appliances may transitionally increase the growth of periodontopathogenic bacteria and consequently result in gingival inflammatory response but without destructive effect on deep periodontal tissues.

Clinical and microbiological effects of fixed orthodontic appliances on periodontal tissues in adolescents

OBJECTIVE

To determine the effects of fixed orthodontic appliances on periodontal health and microbiological composition of subgingival dental plaque.

MATERIAL AND METHODS

This prospective longitudinal self-controlled study was conducted on 32 adolescents (13 males, 19 females), who were scheduled for fixed orthodontic treatment between 2002 and 2005. Dental plaque accumulation, gingival inflammation and pocket probing depth were measured at the mesio-vestibular angle of the examined group of teeth followed by collection of subgingival dental plaque samples in the same points. These periodontal indices and microbiological parameters were determined prior to the placement of fixed appliances and 1, 3 and 6 months after the beginning of orthodontic treatment.

RESULTS

All values of both clinical and microbiological parameters started to increase after the placement of fixed appliances. Maximum values were reached 3 months after fixed appliance placement followed by their decrease in the last registration period of 6 months after the placement of fixed appliances.

CONCLUSIONS

Treatment with fixed appliances in adolescents may transitionally increase the values of all periodontal indices and stimulate the growth of periodontopathogenic bacteria, but without destructive effects on deep periodontal tissues.

Resolvin E1 regulates inflammation at the cellular and tissue level and restores tissue homeostasis in vivo

Resolvin E1 (RvE1) is a potent proresolving mediator of inflammation derived from omega-3 eicosapentaenoic acid that acts locally to stop leukocyte recruitment and promote resolution. RvE1 displays potent counter-regulatory and tissue-protective actions in vitro and in vivo. Periodontal disease is a local inflammatory disease initiated by bacteria characterized by neutrophil-mediated tissue injury followed by development of a chronic immune lesion. In this study, we report the treatment of established periodontitis using RvE1 as a monotherapy in rabbits compared with structurally related lipids PGE(2) and leukotriene B(4). PGE(2) and leukotriene B(4) each enhanced development of periodontitis and worsened the severity of disease. Promotion of resolution of inflammation as a therapeutic target with RvE1 resulted in complete restoration of the local lesion, and reduction in the systemic inflammatory markers C-reactive protein and IL-1beta. This report is the first to show that resolution of inflammation by a naturally occurring endogenous lipid mediator results in complete regeneration of pathologically lost tissues, including bone.

Selective isolation of bacterial DNA from human clinical specimens

We evaluated two DNA preparation strategies (MolYsis, Molzym GmbH & Co. KG, Bremen, Germany) and Pureprove, SIRS-Lab GmbH, Jena, Germany) to selectively extract bacterial DNA from human clinical samples. By testing 16 oral samples we found that human DNA could be largely eliminated while detectable levels of bacterial DNA were obtained with all samples. Both approaches hold great potential for microbial diagnostic systems.

Influence of Sampling Strategy on Microbiologic Results Before and After Periodontal Treatment

BACKGROUND

The aim of this study was to test whether different sampling strategies would influence the microbiologic outcomes by assessing the bacterial load and composition of the subgingival microbiota by means of anaerobic culturing before and after periodontal treatment.

METHODS

The first study (1 versus 4 [1vs4]) included 33 patients with generalized chronic periodontitis. Two sampling strategies were compared, sampling one site from the deepest pocket in the mouth (M1) versus a pooled sample of four sites from the deepest pockets in each quadrant (M4). The second study (2 versus 4 [2vs4]) included 20 patients with generalized chronic periodontitis. The strategy M4 was compared to a pooled sample of two non-adjacent sites in the same quadrant (M2). All samples were processed identically by means of anaerobic culturing. In both studies, a pretreatment sampling was taken. However, in the second study (2vs4), subgingival samples were also taken at 1, 3, and 6 months after periodontal therapy. Quantitative data were compared between strategies by means of t test and signed-rank test; qualitative data were compared by means of 2 x 2 contingency tables.

RESULTS

Pretreatment samples showed that total anaerobic counts were significantly higher for M4 compared to M1 (P <0.001) and M2 (P = 0.025). However, there were no significant differences in regard to percentage of microbiota and counts for each pathogen. Most of the qualitative differences between strategies were caused by false negatives in M1 and M2. Post-treatment samples showed a reduction in total counts and a limited impact in the frequency of detection of periodontal pathogens. M2 detected a significant decrease in the frequency of detection of Porphyromonas gingivalis, which was not confirmed by the M4 strategy.

CONCLUSION

The criteria of selection and the number of sites selected when sampling the subgingival biofilm in patients with generalized chronic periodontitis may influence the detection and quantitation of periodontal pathogens when evaluated by culture especially after treatment.

Comparison of Curet and Paper Point Sampling of Subgingival Bacteria as Analyzed by Real-Time Polymerase Chain Reaction

BACKGROUND

The outcome of microbiological diagnostics may depend on the sampling technique. It was the aim of the present study to compare two widely used sampling techniques for subgingival bacteria using quantitative real-time polymerase chain reaction.

METHODS

Twenty patients with chronic periodontitis were randomized into two groups. In group A, samples were taken first with a paper point and then with a curet at the same site (single-rooted teeth with probing depth >5 mm) before scaling and root planing and after 10 weeks. The sampling sequence was reversed in group B. The analysis enabled the quantification of Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, and Tannerella forsythensis and total bacterial counts (TBCs). Statistical analysis included t test, kappa, and Spearman correlation.

RESULTS

Higher TBC was harvested with curets than by paper points (P = 0.008). The plaque composition with regard to total target pathogens was similar for both sampling techniques. A strong positive correlation was found between curet and paper point samples for TBC and single target bacteria.

CONCLUSIONS

Overall, there was a relatively good agreement for the results of paper point and curet sampling. Thus, both techniques seem to be suitable for microbiological diagnostics.

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.

Periodontal Status in Smokers and Never-Smokers: Clinical Findings and Real-Time Polymerase Chain Reaction Quantification of Putative Periodontal Pathogens

BACKGROUND

Smoking is a well-known risk factor for destructive periodontal disease, but its relationship with periodontal status and subgingival microbiota remains unclear. Inherent limitations of microbiological methods previously used may partly explain these mixed results, and real-time polymerase chain reaction (PCR) has been presented as a valid alternative. The aim of the present study was to investigate the clinical condition and microbiological profile of patients with chronic periodontitis as related to the habit of smoking.

METHODS

Fifty patients (33 to 59 years old), 25 smokers and 25 never-smokers, constituted the sample. The visible plaque index (VPI), gingival bleeding index (GBI), bleeding on probing (BOP), periodontal probing depth (PD), clinical attachment loss (CAL), and gingival crevicular fluid (GCF) volume were recorded. Real-time PCR quantified Porphyromonas gingivalis, Micromonas micros, Dialister pneumosintes, Actinobacillus actinomycetemcomitans and total bacteria in subgingival samples.

RESULTS

Smokers and never-smokers showed similar values for VPI, GBI, and BOP. Smokers had deeper PD in buccal/lingual sites and higher CAL independently of the tooth surface. The GCF volume was smaller in smokers, independent of the PD. Similar amounts of total bacteria and P. gingivalis were observed for both groups. Significantly higher numbers of D. pneumosintes and M. micros were present in smokers and associated with moderate and deep pockets. When heavy smokers were considered, higher counts of total bacteria, M. micros, and D. pneumosintes were observed.

CONCLUSIONS

Smoking seems to have a detrimental impact on the periodontal status and microbiological profile of patients with periodontitis. Compared to never-smokers, smokers had deeper pockets, greater periodontal destruction, and higher counts of some putative periodontal pathogens.

Usefulness of real time PCR for the differentiation and quantification of 652 and JP2 Actinobacillus actinomycetemcomitans genotypes in dental plaque and saliva

BACKGROUND

The aim of our study is to describe a fast molecular method, able to distinguish and quantize the two different genotypes (652 and JP2) of an important periodontal pathogen: Actinobacillus actinomycetemcomitans. The two genotypes show differences in the expression of an important pathogenic factor: the leukotoxin (ltx). In order to evidence this, we performed a real time PCR procedure on the ltx operon, able to recognize Aa clinical isolates with different leukotoxic potentials.

METHODS

The specificity of the method was confirmed in subgingival plaque and saliva specimens collected from eighty-one Italian (Sardinian) subjects with a mean age of 43.9, fifty five (68 %) of whom had various clinical forms of periodontal disease.

RESULTS

This procedure showed a good sensitivity and a high linear dynamic range of quantization (10(7)-10(2) cells/ml) for all genotypes and a good correlation factor (R2 = 0.97-0.98). Compared with traditional cultural methods, this real time PCR procedure is more sensitive; in fact in two subgingival plaque and two positive saliva specimens Aa was only detected with the molecular method.

CONCLUSION

A low number of Sardinian patients was found positive for Aa infections in the oral cavity, (just 10 positive periodontal cases out of 81 and two of these were also saliva positive). The highly leukotoxic JP2 strain was the most representative (60 % of the positive specimens); the samples from periodontal pockets and from saliva showed some ltx genotype for the same patient. Our experience suggests that this approach is suitable for a rapid and complete laboratory diagnosis for Aa infection.

Subgingival distribution of Campylobacter rectus and Tannerella forsythensis in healthy children with primary dentition

OBJECTIVE

It is important to know how many subgingival plaque samples should be assayed from a child to ascertain infection with a periodontal pathogen. Plaque samples from several sites may fail to detect some important bacteria if only a limited number of gingival sites are sampled. The purpose of this study was to evaluate the detection of periodontal pathogens in a large number of subgingival sites in the same children in order to determine the number of samples necessary.

METHODS

Ten children, aged 4-6 years, with complete primary dentition were enrolled in this study. Plaque samples from the mesio-buccal aspect of each erupted tooth were first collected by gently inserting a sterile paper point for 10s. Purified genomic DNA from all plaque samples was prepared for polymerase chain reaction. The primers for species-specific 16S ribosomal RNA sequence were selected as the target sequence. Standard strains of Campylobacter rectus and Tannerella forsythensis (formerly Bacteroides forsythus) were used as control strains.

RESULTS

All subjects were found positive for C. rectus and T. forsythensis with the mean of positive sites at 17.6 +/- 2.4 (range: 12-20 sites) for C. rectus and 9.3 +/- 5.0 (range: 1-19) for T. forsythensis. The mean number of positive sites was 1.7 +/- 0.8 for C. rectus and 6.5 +/- 4.9 for T. forsythensis, with a confidence ratio of 95%.

CONCLUSIONS

We concluded that two or more random sites for C. rectus and seven or more random sites for T. forsythensis from children to detect those bacteria at 95% probability.

Quantitative real-time PCR using TaqMan and SYBR Green for Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, tetQ gene and total bacteria

Accurate quantification of bacterial species in dental plaque is needed for microbiological diagnosis of periodontal diseases. The present study was designed to assess the sensitivity, specificity and quantitativity of the real-time PCR using the GeneAmp Sequence Detection System with two fluorescence chemistries. TaqMan probe with reporter and quencher dye, and SYBR Green dye were used for sources of the fluorescence. Primers and probes were designed for Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia and total bacteria based on the nucleotide sequences of the respective 16S ribosomal RNA genes. Since spread of antibiotic resistance genes is one of the crucial problems in periodontal therapy, quantitative detection of tetQ gene, which confers resistance to tetracycline, was included in the examination. The detection of P. gingivalis, P. intermedia and A. actinomycetemcomitans was linear over a range of 10-10(7) cells (10-10(7) copies for tetQ gene), while the quantitative range for total bacteria was 10(2)-10(7) cells. Species-specific amplifications were observed for the three periodontal bacteria, and there was no significant difference between the TaqMan and SYBR Green chemistry in their specificity, quantitativity and sensitivity. The SYBR Green assay, which was simpler than TaqMan assay in its manipulations, was applied to the clinical plaque samples. The plaque samples were obtained from eight patients (eight periodontal pockets) before and 1 week after the local drug delivery of minocycline. Although the number of P. gingivalis, P. intermedia and A. actinomycetemcomitans markedly decreased after the antibiotic therapy in most cases, higher copy numbers of the tetQ gene were detectable. The real-time PCR demonstrated sufficient sensitivity, specificity and quantitativity to be a powerful tool for microbiological examination in periodontal disease, and the quantitative monitoring of antibiotic resistance gene accompanied with the antibiotic therapy should be included in the examination.

Superinfecting microorganisms in patients under treatment with cyclosporin-A and its correlation to gingival overgrowth

The aim of this study was to identify the presence of superinfecting microorganisms (Gram-negative enteric rods and Candida sp.) in heart transplant patients and correlate this with gingival overgrowth. Thirty patients (10 females, 20 males--mean age 45 years) were examined. All were under cyclosporin-A (CsA) therapy. Patients who had taken any antibiotics 3 months prior the study or had been submitted to periodontal therapy were not enrolled. Patients were required to have at least 6 teeth. The plaque index (PI), gingival index (GI), pocket depth (PD) and clinical attachment level (CAL) were recorded. Microbiological samples were taken from sulcus/pocket (s/p) and from stimulated saliva (ss) and submitted to analysis. Patients were divided into two groups: the ones with gingival overgrowth (GO) and those without gingival overgrowth (WGO). After statistical analysis (chi-square test, Student's t-test, Fisher test, p < or = 0.05), we concluded that there was no statistical difference between groups in the parameters of gender, CsA dosage, time since transplantation, PI, GI, PD and CAL. Gram-negative rods from either the sulcus/pocket or saliva samples were not found. Candida sp. was detected (s/p-30% and ss-30%). Stimulated saliva samples analysis determined that the presence of Candida sp. was associated with patients without gingival overgrowth.

DNA probes and primers in dental practice

In clinical microbiology, molecular genetic techniques are increasingly being used to detect and/or differentiate uncultivable, anaerobic, or fastidious microorganisms. During the past decade, DNA probe hybridization and in vitro amplification by polymerase chain reaction have also been introduced to detect oral pathogens. The present review describes experiences with methods and commercial test systems for the detection of pathogens in periodontitis and caries.