Microbiological diagnostics in periodontics: biological significance and clinical validity

A method for Porphyromonas gingivalis based on recombinase polymerase amplification and lateral flow strip technology

OBJECTIVE

A practical visual detection method was established to detect Porphyromonas gingivalis (P. gingivalis) by employing a combination of recombinase polymerase amplification and lateral flow strips (RPA-LF) assay, designed for conducting point-of-care testing in clinical settings.

METHODS

Primers and probes targeting the P. gingivalis pepO gene were designed. The RPA-LF assay was established by optimising reaction temperature and time, determining the limit of detection (LOD). The specificity of the method was determined by assessing its cross-reactivity with deoxyribonucleic acid from 23 pathogenic bacteria. Finally, the clinical samples from healthy controls (n = 30) and individuals with periodontitis (n = 31) were analysed. The results were compared with those obtained using real-time polymerase chain reaction (PCR).

RESULTS

The optimal reaction temperature and time were 39 °C and 12 min. The method exhibited a LOD at 6.40 × 10-4 μg/mL and demonstrated high specificity and sensitivity during cross-reactivity assessment. The RPA-LF assay achieved a P. gingivalis detection rate of 84 % in individuals with periodontitis and 3 % in healthy controls. The results were consistent with those obtained through real-time PCR.

CONCLUSION

An RPA-LF assay was developed for detecting P. gingivalis, characterised by its high sensitivity, high specificity, simple operational procedure, and rapid reaction time.

Europe's contribution to the evaluation of the use of systemic antimicrobials in the treatment of periodontitis

This narrative review celebrates Europe's contribution to the current knowledge on systemically administered antimicrobials in periodontal treatment. Periodontitis is the most frequent chronic noncommunicable human disease. It is caused by dysbiotic bacterial biofilms and is commonly treated with subgingival instrumentation. However, some sites/patients do not respond adequately, and its limitations and shortcomings have been recognized. This has led to the development of alternative or adjunctive therapies. One is the use of antimicrobials to target bacteria in subgingival biofilms in the periodontal pocket, which can be targeted directly through the pocket entrance with a locally delivered antibiotic or systemically by oral, intravenous, or intramuscular methods. Since the early 20th century, several studies on systemic antibiotics have been undertaken and published, especially between 1990 and 2010. Europe's latest contribution to this topic is the first European Federation of Periodontology, S3-level Clinical Practice Guideline, which incorporates recommendations related to the use of adjuncts to treat stage I-III periodontitis. Understanding the etiopathogenesis of periodontal diseases, specifically periodontitis, has influenced the use of systemic periodontal antibiotic therapy. Randomized clinical trials and systematic reviews with meta-analyses have demonstrated the clinical advantages of adjunctive systemic antimicrobials. However, current recommendations are restrictive due to concerns about antibiotic misuse and the increase in microbial antibiotic resistance. European researchers have contributed to the use of systemic antimicrobials in the treatment of periodontitis through clinical trials and by providing rational guidelines. Nowadays, European researchers are exploring alternatives and directing clinical practice by providing evidence-based guidelines to limit the use of systemic antimicrobials.

Influence of Anti-Infective Periodontal Therapy on Subgingival Microbiota Evaluated by Chair-Side Test Compared to qPCR—A Clinical Follow-Up Study

A chair-side test (CST) for five periodontal pathogens (Aggregatibacter actinomycetemcomitans, A.a.; Porphyromonas gingivalis, P.g.; Prevotella intermedia, P.i.; Treponema denticola, T.d.; Tannerella forsythia, T.f.) was compared with qPCR in a previous clinical study on 100 periodontitis patients at first diagnosis (T0). Following non-surgical treatment alone (SRP) or in combination with systemic or local antibiotics, 74 patients (57.4 ± 13.5 years) were again tested at the same sites from 14 to 24 months after T0. Bacterial elimination (%; compared to T0) was determined for each single species and compared between both test systems. In all patients, all five pathogens could not be fully eliminated regardless of therapy or test method. Tested with CST, the mean elimination ranged from 90% for SRP + Amoxicillin/Metronidazole to 59.13% for SRP only. The corresponding qPCR values were 30% and 29.6%. Only A.a. was eradicated in 100% by SRP + Amoxicillin/Metronidazole tested by CST, and it was 80% when qPCR was the test method. CST agreed with qPCR in 98.7% in the detection of A.a., and 74.3%, 78.4%, 73.0%, and 48.7% for P.g., P.i., T.d., and T.f., respectively. Neither conventional treatment nor the additional use of antibiotics—even with the correct indication—could completely eradicate the tested pathogens or prevent pocket reinfection.

Personalized and Defect-Specific Antibiotic-Laden Scaffolds for Periodontal Infection Ablation

Periodontitis compromises the integrity and function of tooth-supporting structures. Although therapeutic approaches have been offered, predictable regeneration of periodontal tissues remains intangible, particularly in anatomically complex defects. In this work, personalized and defect-specific antibiotic-laden polymeric scaffolds containing metronidazole (MET), tetracycline (TCH), or their combination (MET/TCH) were created via electrospinning. An initial screening of the synthesized fibers comprising chemo-morphological analyses, cytocompatibility assessment, and antimicrobial validation against periodontopathogens was accomplished to determine the cell-friendly and anti-infective nature of the scaffolds. According to the cytocompatibility and antimicrobial data, the 1:3 MET/TCH formulation was used to obtain three-dimensional defect-specific scaffolds to treat periodontally compromised three-wall osseous defects in rats. Inflammatory cell response and new bone formation were assessed by histology. Micro-computerized tomography was performed to assess bone loss in the furcation area at 2 and 6 weeks post implantation. Chemo-morphological and cell compatibility analyses confirmed the synthesis of cytocompatible antibiotic-laden fibers with antimicrobial action. Importantly, the 1:3 MET/TCH defect-specific scaffolds led to increased new bone formation, lower bone loss, and reduced inflammatory response when compared to antibiotic-free scaffolds. Altogether, our results suggest that the fabrication of defect-specific antibiotic-laden scaffolds holds great potential toward the development of personalized (i.e., patient-specific medication) scaffolds to ablate infection while affording regenerative properties.

Microbiological testing of clinical samples before and after periodontal treatment. A comparative methodological study between real-time PCR and real-time-PCR associated to propidium monoazide

Objectives

The aim of the present methodological study was to evaluate the discrepancies in the detection of a number of periodontally involved pathogenic bacteria obtained from clinical samples by two methods: the quantitative Polymerase Chain Reaction (qPCR) and the qPCR combined with pre‐treatment by Propidium Monoazide (PMA).

Material and methods

Plaque and saliva samples were obtained from 30 subjects: 20 subjects with chronic or aggressive periodontitis in need of periodontal therapy with or without antibiotics and 10 subjects in Supportive Periodontal Treatment (SPT). The clinical samples taken before treatment (BL) and 1 month later (M1), were divided in two aliquots: one was immediately treated with PMA while the other was left untreated. All samples were further analyzed with qPCR after DNA extraction, for the detection of Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), Parvimonas micra (Pm), and Prevotella intermedia (Pi).

Results

Large inter‐individual variations were observed in the concentration of the studied bacteria. At both instances (BL and M1) and for the three groups, significantly lower counts of bacteria were depicted when plaque and saliva samples were pre‐treated with PMA as compared to those without treatment. Treatment resulted in significant decreases in the number of bacteria, mainly in the plaque samples. However, these changes were almost similar in the three groups independently of the method of detection used (PMA‐qPCR vs. q‐PCR).

Conclusion

Removal of DNA from non‐viable cells with PMA treatment is an easily applied step added to the classical qPCR that could give accurate information on the presence of viable bacterial load and evaluate the response to periodontal treatment.

Comparison of three qPCR-based commercial tests for detection of periodontal pathogens

In periodontal practice microbial results of periodontal test kits for identification of key pathogens are an aid in the treatment planning. Information on the performance of commercially available test kits is therefore essential for the clinician. In this retrospective analysis three commercially available qPCR kits for detection and quantification of selected periodontal bacterial species were compared, using 100 clinical samples from patients with untreated periodontitis. The analysis involved two separate comparisons in which kit A (LabOral Diagnostics, The Netherlands) was compared with kit B (Advanced Dental Diagnostics, The Netherlands), and with kit C (OralDent diagnostics, The Netherlands). Analytic procedures for detection and quantification of selected periodontal bacterial species were carried out according to the instructions of the laboratories. Kit A detected target species more often, and absolute numbers of bacterial cells were higher than with kit B. A high degree of similarity was found between the test outcomes by kit A and kit C. All three kits performed satisfactory but small and significant differences exist between kits.

Changes in clinical and microbiological parameters of the periodontium during initial stages of orthodontic movement in patients with treated severe periodontitis: A longitudinal site-level analysis

Applying orthodontic braces makes oral hygiene difficult and increases plaque accumulation, frequently resulting in gingival inflammation. In patients with previous severe periodontitis, this inflammation overlaps with the pre-existing inflammatory challenge and can lead to further progression of periodontal attachment loss. The aim of this study was to assess longitudinal site-level changes as mirrored by clinical and microbiological parameters during the initial remodeling of alveolar bone and the periodontal ligament, produced as an effect of light orthodontic forces in adult patients with severe periodontal disease that underwent standard (non-surgical and conventional surgical) periodontal therapy. Thirteen patients with previously treated severe generalized periodontitis were given fixed orthodontic appliances for re-alignment of teeth misaligned or displaced during the course of periodontitis. Before insertion of orthodontic appliances and at 2, 4, and 6 months of treatment, periodontal clinical parameters were recorded in the same deepest residual pocket of at least 3 mm in each patient. The same pocket was sampled at baseline and after 6 months of orthodontic treatment for the frequency of positive detection of Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Tanerella forsythia (Tf), Treponema denticola (Td). An average reduction in Pocket Depth by 0.2 mm at the end of the assessment period was identified. The only clinical parameter with statistically significant improvement was bleeding on probing. The frequency of detection of Aa, Pg, Pi, and Tf was not significantly different between baseline and 6 months of treatment, while a marginally significant increase of Td was found. There were no significant differences in the clinical parameters or microflora in the initial phase of orthodontic treatment in patients with reduced periodontal support. By correlating clinical and microbiological data, we concluded that the presence of periopathogens do not negatively influence periodontal health during orthodontic treatment in adult patients treated for severe periodontitis.

Systemic doxycycline as an adjunct to scaling and root planing in diabetic patients with periodontitis: a systematic review and meta-analysis

BACKGROUND

To compare the effectiveness of systemic doxycycline as an adjunct to scaling and root planing (SRP) with SRP alone in improving periodontal clinical attachment level and glycemic control in diabetic patients with periodontitis.

METHODS

Two independent reviewers (KY and SJ) screened two electronic databases, PubMed and Scopus, for randomized clinical trials on the use of systemic doxycycline as an adjunct to scaling and root planing in improving periodontal status and glycemic control in diabetic patients with periodontitis using predetermined selection criteria within a 3-month period. The reviewers independently did data screening, data selection, data extraction and risk of bias. Quality of studies involved was analysed using the revised Cochrane Risk of Bias 2.0. Weighted standard mean differences (SMD) and 95% confidence intervals were calculated using a random effects meta-analysis model. Publication bias was evaluated using funnel plot. Quality of evidence was evaluated by Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Electronic searches provided 1358 records and six studies were selected. The meta-analyses indicated that there was no statistically significant difference in the improvement of periodontal status with the use of systemic doxycycline as an adjunct for scaling and root planing (SRP). SMD of clinical attachment levels (- 0.22 [- 0.52, 0.08]) and HbA1c levels (- 0.13 [- 0.41, 0.15]) were calculated. Overall risk of bias is high in 2 out of 6 studies involved.

CONCLUSION

Systemic doxycycline when used in addition to scaling and root planing yields no significant improvement of clinical attachment levels for periodontal status and reduction of HbA1c levels in treatment of diabetic patients with periodontitis when comparing the test group to the control group.

Validation of a multiplex qPCR assay for the identification and quantification of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis: In vitro and subgingival plaque samples

OBJECTIVE

To validate a multiplex qPCR (m-qPCR) assay for the simultaneous identification and quantification of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis in subgingival samples.

MATERIAL AND METHODS

In vitro samples: DNA combinations of A. actinomycetemcomitans and P. gingivalis in similar or different concentrations were prepared. qPCR and m-qPCR were performed using the same primers and hydrolysis probes specific for 16SrRNA genes. Results were analyzed using intra-class (ICCs) and Lin's correlation coefficients (r) based on quantification cycle (Cq) values. Subgingival plaque samples: a cross-sectional study analyzing subgingival plaque samples harvested from periodontally-healthy and chronic periodontitis patients. Samples were processed by either qPCR or m-qPCR targeting both bacteria. Sensitivity, specificity, predictive values and Lińs correlation coefficients (r) were calculated using CFU/mL as primary outcome.

RESULTS

In vitro samples: m-qPCR yielded a good reproducibility (coefficients of variation around 1% and ICCs > 0.99) for both bacterial species. m-qPCR achieved detection limits and specificity similar to qPCR. An excellent concordance (r = 0.99) was observed between m-qPCR and qPCR for A. actinomycetemcomitans and P. gingivalis without statistical significant differences between both methods Subgingival plaque samples: a high sensitivity (above 80%) and specificity (100%) was obtained with the m-qPCR for both bacteria. The m-qPCR yielded a good concordance in Cq values, showing a good level of agreement between qPCR and m-qPCR.

CONCLUSION

The tested m-qPCR method was successful in the simultaneous quantification of A. actinomycetemcomitans and P. gingivalis, with a high degree of sensitivity and specificity on subgingival plaque samples.

Microbial colonization of the periodontal pocket and its significance for periodontal therapy

The aim of this paper was to evaluate strategies for periodontal therapy from the perspective of periodontal disease being a consequence of microbial colonization of the periodontal pocket environment. In classic bacterial infections the diversity of the microbiota decreases as the disease develops. In most cases of periodontitis, however, the diversity of the flora increases. Most incriminating bacteria are thought to harm tissues significantly only if present in high numbers over prolonged periods of time. Clinical trials have repeatedly demonstrated that scaling and root planing, a procedure that aims to remove subgingival bacterial deposits by scraping on the tooth surface within the periodontal pocket, is effective. At present, for the therapy of any form of periodontal disease, there exists no protocol with proven superiority, in terms of efficiency or effectiveness, over scaling and root planing plus systemic amoxicillin and metronidazole. Some exponents advocate rationing these drugs for patients with a specific microbial profile. However, the evidence for any benefit of bacteriology-assisted clinical protocols is unsatisfactory. Treated sites are subject to recolonization with a microbiota similar to that present before therapy. The degree and speed of recolonization depends on the treatment protocol, the distribution patterns of periodontal microorganisms elsewhere in the oral cavity and the quality of the patient's oral hygiene. To limit the use of antibiotics and to avoid accumulation of harmful effects by repeated therapy, further efforts must be made to optimize procedures addressing the microbial colonization and recolonization of the periodontal pocket.

Comparison of adjunctive azithromycin and amoxicillin/metronidazole for patients with chronic periodontitis: preliminary randomized control trial

BACKGROUND

There are insufficient guidelines for the use of adjunctive systemic antibiotics for patients with periodontal disease. The aim of this study was to compare clinical outcomes for patients with moderate-advanced chronic periodontitis treated with: scaling and root planing (SRP), SRP with amoxicillin and metronidazole (A+M), SRP with Azithromycin (Az).

METHODS

Thirty-seven non-smokers with generalized moderate to advanced chronic periodontitis were divided into three treatment groups: SRP, A+M and Az. Patients received the medications after the last SRP session and were reviewed three months later. Changes in clinical parameters were compared between the groups. Separate analyses were executed for: 'all sites', 'molar sites', 'sites with different PPD severities' and 'number of sites with shallow, moderate and deep PPD'.

RESULTS

The three groups exhibited improvements in most clinical parameters. At three months, A+M showed a higher reduction in PPD compared to Az in the 'all sites analysis'. Molars exhibited better reduction in BOP and PPD with A+M than SRP. Pocket depth of the 4-6 mm category reduced more in the A+M than SRP. A+M experienced a higher increase in the number of sites with PPD 1-3 mm than Az.

CONCLUSIONS

Adjunctive systemic antibiotics in the initial phase of treatment may result in improved clinical outcomes.

Antibiotic-prescribing habits among Norwegian dentists: a survey over 25 years (1990-2015)

Bacterial antibiotic resistance is a steadily growing global problem, which today is compared with issues such as global warming, ozone depletion, and extinction of species. Consequently, calls come from global, Pan-European, and national authorities to gain insight into, limit, and stringently qualify the use of antibiotics in human and veterinary medicine, as well as in food production. Dentists are not considered to be frequent prescribers of antibiotics. However, few studies have identified how much, and in which situations, dentists prescribe such drugs. The aims of the present study were to survey Norwegian dentists' antibiotic-prescribing habits in 2015 and to compare the findings with previous studies (1990 and 2004) and with the actual numbers of dispensed prescriptions obtained from the 'Norwegian National Prescription Register'. The results from 1990 to 2004 show that there was a general increase in antibiotic prescriptions by Norwegian dentists, followed by a reduction or flattening of the prescription volume curve from 2004 to 2015. Despite this, possibilities for further improvements have been identified and recommendations given for targeted campaigns to reduce the prescription volume in dentistry by a further 30%, which has been ordered by the Norwegian National Assembly.

Introduction to Clinical Microbiology for the General Dentist

Clinical oral microbiology may help dental professionals identify infecting pathogenic species and evaluate their in vitro antimicrobial susceptibility. Saliva, dental plaque biofilms, mucosal smears, abscess aspirates, and soft tissue biopsies are sources of microorganisms for laboratory testing. Microbial-based treatment end points may help clinicians better identify patients in need of additional or altered dental therapies before the onset of clinical treatment failure, and help improve patient oral health outcomes. Microbiological testing appears particularly helpful in periodontal disease treatment planning. Further research and technological advances are likely to increase the availability and clinical utility of microbiological analysis in modern dental practice.

Systemic moxifloxacin vs amoxicillin/metronidazole adjunct to non-surgical treatment in generalized aggressive periodontitis

Background

The objective of this randomized clinical study was to evaluate the effect of systemic administration of moxifloxacin compared to amoxicillin and metronidazole, combined with non-surgical treatment in patients with generalized aggressive periodontitis (GAgP) in a 6-month follow-up.

Material and Methods

A total of 39 systemically healthy patients with GAgP were evaluated in this randomized clinical trial. Periodontal parameters were recorded at the baseline during the 1st, 3rd and 6th month. Patients received either 400 mg of moxifloxacin per os once daily or 500 mg of metronidazole and 500 mg amoxicillin per os three times daily for 7 days consecutively.

Results

No significant differences between groups were found in any parameters at the baseline. Both groups led to a statistically significant decrease in all clinical periodontal parameters compared to the baseline (PI, p<0.001 and GI, PD, BOP, CAL, p<0.01). There were no differences between the 1st and 3rd months or the 3rd and 6th months for clinical parameters in the groups. Also, no intergroup difference was observed in any parameters at any time, except the gingival index at 6th months.

Conclusions

Systemic administration of moxifloxacin as an adjunct to non-surgical treatment significantly improves clinical outcomes and provides comparable clinical improvement with less adverse events to that of combination of amoxicillin and metronidazole in the treatment of GAgP.

Key words: Aggressive periodontitis, amoxicillin, metronidazole, moxifloxacin, nonsurgical periodontal debridement.

16S rRNA based microarray analysis of ten periodontal bacteria in patients with different forms of periodontitis

DNA microarray analysis is a computer based technology, that a reverse capture, which targets 10 periodontal bacteria (ParoCheck) is available for rapid semi-quantitative determination. The aim of this three-year retrospective study was to display the microarray analysis results for the subgingival biofilm samples taken from patient cases diagnosed with different forms of periodontitis. A total of 84 patients with generalized aggressive periodontitis (GAP,n:29), generalized chronic periodontitis (GCP, n:25), peri-implantitis (PI,n:14), localized aggressive periodontitis (LAP,n:8) and refractory chronic periodontitis (RP,n:8) were consecutively selected from the archives of the Oral Microbiological Diagnostic Laboratory. The subgingival biofilm samples were analyzed by the microarray-based identification of 10 selected species. All the tested species were detected in the samples. The red complex bacteria were the most prevalent with very high levels in all groups. Fusobacterium nucleatum was detected in all samples at high levels. The green and blue complex bacteria were less prevalent compared with red and orange complex, except Aggregatibacter actinomycetemcomitas was detected in all LAP group. Positive correlations were found within all the red complex bacteria and between red and orange complex bacteria especially in GCP and GAP groups. Parocheck enables to monitoring of periodontal pathogens in all forms of periodontal disease and can be alternative to other guiding and reliable microbiologic tests.

Differential benefits of amoxicillin-metronidazole in different phases of periodontal therapy in a randomized controlled crossover clinical trial

BACKGROUND

The specific advantage of administering systemic antibiotics during initial, non-surgical therapy or in the context of periodontal surgery is unclear. This study assesses the differential outcomes of periodontal therapy supplemented with amoxicillin-metronidazole during either the non-surgical or the surgical treatment phase.

METHODS

This is a single-center, randomized placebo-controlled crossover clinical trial with a 1-year follow-up. Eighty participants with Aggregatibacter actinomycetemcomitans-associated moderate to advanced periodontitis were randomized into two treatment groups: group A, antibiotics (500 mg metronidazole plus 375 mg amoxicillin three times per day for 7 days) during the first, non-surgical phase of periodontal therapy (T1) and placebo during the second, surgical phase (T2); and group B, placebo during T1 and antibiotics during T2. The number of sites with probing depth (PD) >4 mm and bleeding on probing (BOP) per patient was the primary outcome.

RESULTS

A total of 11,212 sites were clinically monitored on 1,870 teeth. T1 with antibiotics decreased the number of sites with PD >4 mm and BOP per patient significantly more than without (group A: from 34.5 to 5.7, 84%; group B: from 28.7 to 8.7, 70%; P <0.01). Twenty patients treated with antibiotics, but only eight treated with placebo, achieved a 10-fold reduction of diseased sites (P = 0.007). Consequently, fewer patients of group A needed additional therapy, the mean number of surgical interventions was lower, and treatment time in T2 was shorter. Six months after T2, the mean number of residual pockets (group A: 2.8 ± 5.2; group B: 2.2 ± 5.0) was not significantly different and was sustained over 12 months in both groups.

CONCLUSION

Giving the antibiotics during T1 or T2 yielded similar long-term outcomes, but antibiotics in T1 resolved the disease quicker and thus reduced the need for additional surgical intervention.

Determination of periodontopathogens in patients with Cri du chat syndrome

Objectives: Cri du chat syndrome is a genetic alteration associated with some oral pathologies. However, it has not been described previously any clinical relationship between the periodontal disease and the syndrome. The purpose of this comparative study was to compare periodontopathogenic flora in a group with Cri du chat syndrome and another without the síndrome, to assess a potential microbiological predisposition to suffer a periodontitis. Study Design: The study compared nineteen subjects with Cri du chat Syndrome with a control group of nineteen patients without it. All patients were clinically evaluated by periodontal probing, valuing the pocket depth, the clinical attachmente level and bleeding on probing. There were no significant differences between both groups. Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia and Treponema denticola were detected by multiplex-PCR using 16S rDNA (microIDENT). Results: When A. actinomycetemcomitans, P. gingivalis, P. intermedia and T. denticola were compared, no statistically significant differences were found between the two groups (p>0.05). The value of T. forsythia was significantly higher for Cri du chat syndrome (31.6%) than for the control group (5.3%). The odds ratio for T. forsythia was 8.3. Conclusions: In the present study T. forsythia is associated with Cri du chat syndrome subjects and not with healthy subjects.

Key words:Cri du Chat syndrome, periodontal health, microbiology, special care dentistry.

Does routine analysis of subgingival microbiota in periodontitis contribute to patient benefit?

In clinical periodontology it is common practice to sample subgingival plaque from periodontitis patients and to search for the presence of alleged periodontal pathogens using routine laboratory techniques such as culture, DNA-DNA hybridization or real-time PCR. Usually, special attention is given to the recognition of 'red complex' microorganisms and to Aggregatibacter actinomycetemcomitans. Recently, molecular open-ended techniques have been introduced which are distinct from the more 'classical' approaches in that they do not preselect for certain species. In this study, we investigated to what extent the outcome of these techniques has changed our insight into the composition of the subgingival microbiota and whether this has consequences on clinical decision making. The open-ended approaches showed that the composition of subgingival plaque is much more complex than previously thought. Next to the 'classical' putative periodontal pathogens, several non-culturable and fastidious species are now recognized as being associated with periodontitis, thus enlarging the group of suspected periodontal pathogens. We conclude that routine analyses of subgingival plaque in the clinic are not necessarily of benefit to the patient.

Patient-related risk factors for tooth loss in aggressive periodontitis after active periodontal therapy

OBJECTIVES

Evaluation of patient-related risk factors contributing to tooth loss and recurrence of periodontitis 10.5 years after initial therapy in patients with aggressive periodontitis (AgP).

MATERIAL AND METHODS

Eighty-four of 174 patients were included. Re-examination consisted of patient's history, clinical examination and test for interleukin (IL)-1 composite genotype. Patients' charts were searched for regularity of maintenance and initial diagnosis. Statistical analysis was performed using Poisson and logistical regression analysis.

RESULTS

The responder rate was 48%. Thirteen of 84 patients presented a localized AgP, 68 were females and 29 smoked. One hundred and thirteen teeth out of 2154 were lost after therapy (1.34 teeth/patient). Age (p=0.0018), absence of IL-1 composite genotype (p=0.0091) and educational status (p=0.0085) were identified as statistically significant risk factors for tooth loss. Twenty patients exhibited recurrence of periodontitis at re-examination. Smoking (p=0.0034) and mean Gingival Bleeding Index (GBI) (p=0.0239) contributed significantly to recurrence of disease. No patient participating regularly in supportive periodontal therapy (SPT) showed disease recurrence.

CONCLUSION

Age, absence of IL-1 composite genotype and low social status are detected as risk factors for tooth loss. Smoking and high mean GBI are associated with an increased risk for recurrence of periodontitis, whereas regular SPT acts as a protective factor.

Prevalence of tetM, tetQ, nim and bla(TEM) genes in the oral cavities of Greek subjects: a pilot study

AIM

To investigate the prevalence of tetM, tetQ, nim and bla(TEM) antimicrobial resistance genes in subgingival and tongue samples of Greek subjects.

MATERIALS AND METHODS

Fifty-four subjects participated in the present study. Participants each contributed with one pooled subgingival sample from the mesiobuccal surface of the four first molars and one sample from the tongue. Samples were analysed using polymerase chain reaction for tetM, tetQ, nim and bla(TEM) genes using the primers and conditions described previously. Subjects were stratified according to periodontal status (health, gingivitis or periodontitis). Intake of any antibiotic for medical or dental reasons during the previous 12 months was also recorded (self-reported). Comparisons within and between groups were performed by applying non-parametric tests (z-test with Bonferroni corrections).

RESULTS

A high prevalence of tetM, tetQ and bla(TEM) genes was detected in both tongue and subgingival samples (48.1-82.2%). No differences were observed across genes between periodontally healthy, gingivitis or periodontitis cases, and no statistical correlation was observed between the presence of the bla(TEM) gene and the intake of beta-lactams during the last 12 months (Fisher's exact test, p>0.05).

CONCLUSIONS

Findings from the present study suggest a high prevalence of tetM, tetQ and bla(TEM), but not nim resistance genes in subgingival and tongue samples from Greek subjects.

Salivary detection of periodontopathic bacteria in periodontally healthy children

BACKGROUND

Salivary occurrence of periodontopathic bacteria is of interest especially in children as a risk indicator for the transmission, development and control of periodontal disease. We assessed the prevalence of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia, Prevotella nigrescens and Treponema denticola as microbial complexes in the saliva of children with mixed dentition and healthy gingiva.

MATERIALS AND METHODS

Paraffin-stimulated saliva samples were collected from 41 children (22 boys and 19 girls), aged 6-13 years old. Gingival health was determined during the initial screening exam. The test bacteria were identified using a 16S rRNA-based PCR analysis.

RESULTS

P. nigrescens was the most frequent species (80%), followed by T. denticola (32%), A. actinomycetemcomitans (24%) and P. gingivalis (12%). P. intermedia and T. forsythia were not detected. P. nigrescens was also common species in combinations. Paired and triple bacterial combinations were found in 24% and 20% of all children, respectively. There was no positive association between bacterial combinations in colonization and subject's gender (P>0.05, Fisher exact test).

CONCLUSION

The salivary presence of P. nigrescens, T. denticola, A. actinomycetemcomitans and P. gingivalis but not P. intermedia and T. forsythia can occur in childhood without clinical signs of gingival disease. Thus, the possible risk of bacterial transmissions through saliva and, the need to screen for periodontal pathogens should be considered before mixed dentition.

A retrospective clinical, radiographic and microbiological study of periodontal conditions of teeth with and without crowns

The aim of this study was to evaluate retrospectively the periodontal conditions of teeth with fixed crowns that had been in place from 3 to 5 years before the study was conducted. Forty individuals were recalled for a follow-up visit. Full-mouth clinical examinations were carried out and Visible Plaque Index (VPI), Gingival Bleeding Index (GBI), Probing Pocket Depth (PPD), and clinical attachment level (CAL) were assessed in 6 sites per tooth. Parallel radiographs were also taken and blindly analyzed by a digital caliper (distance between the apex and the bone crest). BANA tests were performed. A contra-lateral sound tooth was considered the control. Mean values were obtained and Wilcoxon and paired sample t tests were used to compare the test and control sites. Crowns had a mean VPI value of 30.42% as compared to 49.17% for sound teeth. The GBI was 33.33% and 26.25% for test and control teeth respectively. Assessment of PPD revealed values of 2.30 and 2.14 mm, and assessment of CAL revealed averages of 2.02 and 1.89 mm for test and control teeth respectively. The mean values for radiographic distances were 12.73 and 13.67 mm, and for the BANA test, 67.50 and 50.00 for sound and crowned teeth, respectively. Statistically significant differences were observed for all parameters except for CAL and for the BANA test. It may be concluded that, with the methods used in the present study, crowns may be associated with more signs of inflammation, however not with periodontal breakdown.