Gerhard Schmalz

Detection of five potentially periodontal pathogenic bacteria in peri-implant disease: A comparison of PCR and real-time PCR

The aim of this study was to compare the microbial analysis methods of polymerase chain reaction (PCR) and real-time PCR (RT-PCR) in terms of detection of five selected potentially periodontal pathogenic bacteria in peri-implant disease. Therefore 45 samples of healthy, mucositis and peri-implantitis (n = 15 each) were assessed according to presence of the following bacteria using PCR (DNA-strip technology) and RT-PCR (fluorescent dye SYBR green-system): Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Treponema denticola (Td), Tanerella forsythia (Tf), and Fusobacterium nucleatum (Fn). There were no significant correlations between the bacterial and disease patterns, so the benefit of using microbiological tests for the diagnosis of peri-implant diseases is questionable. Correlations between the methods were highest for Tf (Kendalls Tau: 0.65, Spearman: 0.78), Fn (0.49, 0.61) and Td (0.49, 0.59). For Aa (0.38, 0.42) and Pg (0.04, 0.04), lower correlation values were detected. Accordingly, conventional semi-quantitative PCR seems to be sufficient for analyzing potentially periodontal pathogenic bacterial species.

MicroRNAs as Salivary Markers for Periodontal Diseases: A New Diagnostic Approach?

The aim of this review is to discuss current findings regarding the roles of miRNAs in periodontal diseases and the potential use of saliva as a diagnostic medium for corresponding miRNA investigations. For periodontal disease, investigations have been restricted to tissue samples and five miRNAs, that is, miR-142-3p, miR-146a, miR-155, miR-203, and miR-223, were repeatedly validated in vivo and in vitro by different validation methods. Particularly noticeable are the small sample sizes, different internal controls, and different case definitions of periodontitis in in vivo studies. Beside of that, the validated miRNAs are associated with inflammation and therefore with various diseases. Furthermore, several studies successfully explored the use of salivary miRNA species for the diagnosis of oral cancer. Different cancer types were investigated and heterogeneous methodology was used; moreover, no overlap of results was found. In conclusion, five miRNAs have consistently been reported for periodontitis; however, their disease specificity, detectability, and expression in saliva and their importance as noninvasive markers are questionable. In principle, a salivary miRNA diagnostic method seems feasible. However, standardized criteria and protocols for preanalytics, measurements, and analysis should be established to obtain comparable results across different studies.

Active matrix metalloproteinase‐8 and periodontal bacteria depending on periodontal status in patients with rheumatoid arthritis

BACKGROUND AND OBJECTIVES The aim of this clinical cross-sectional study was to determine the level of active matrix metalloproteinase-8 (aMMP-8) and periodontal pathogenic bacteria in gingival crevicular fluid in patients with rheumatoid arthritis (RA) with varying periodontal conditions. MATERIAL AND METHODS In total, 103 patients with RA and 104 healthy controls (HC) were included. The assessment of periodontal status included periodontal probing depth, bleeding on probing and clinical attachment loss. Periodontal disease was classified as healthy/mild, moderate or severe. For the determination of aMMP-8 levels using enzyme-linked immunosorbent assay and periodontal pathogenic bacteria using polymerase chain reaction, samples of gingival crevicular fluid were taken from the deepest gingival pockets. The statistical analyses used included a Mann-Whitney U-test, a chi-squared test or a Fishers exact test, and the significance level was set at α = 5%. RESULTS We found that 65% of patients with RA and 79% of HC had moderate to severe periodontal disease (p = 0.02). The prevalence of periodontal pathogens was almost equal (p > 0.05). Furthermore, depending on periodontal disease severity only minor differences in bacterial prevalence were detected. With increasing severity of periodontal disease, higher aMMP-8 levels were observed. Accordingly, a significant difference in patients with moderate periodontal disease (RA: 15.3 ± 13.8; HC: 9.1 ± 9.1; p ≤ 0.01) and severe periodontal disease (RA: 21.7 ± 13.3; HC: 13.1 ± 8.6; p = 0.07) was detected, with a greater tendency in the latter group. CONCLUSION The increased aMMP-8 levels in the RA group indicate that the presence of RA appears to have an influence on the host response at a comparable level of bacterial load and periodontal disease severity.

Oral findings and dental behaviour before and after liver transplantation – a single-centre cross-sectional study

OBJECTIVE The aim of this single-centre, cross-sectional study was to evaluate dental, periodontal and mycological findings, as well as oral behaviour, in patients before (pre-LTx) and after (post-LTx) liver transplantation. METHODS A total of 47 patients pre-LTx and 119 patients post-LTx were asked to participate. Oral health behaviour was assessed using a standardised questionnaire. Oral examinations included dental [decayed, missing and filled teeth (DMFT) index] and periodontal [papillary bleeding index (PBI), periodontal probing depth (PPD) and clinical attachment loss (CAL)] findings. For Candida screening, swabs from the oral mucosa were cultured. Statistical analysis was performed using the Students t-test or the Mann-Whitney U-test, depending on whether or not the data followed a normal distribution; Fishers exact test was also performed. The significance level was α = 5%. RESULTS A total of 110 patients were included (pre-LTx, n = 35; post-LTx, n = 75). Different patients were investigated in the post-LTx and pre-LTx groups. Lack of use of supplemental oral-hygiene aids was noted. Between-group comparisons failed to find significant overall differences in DMFT and periodontal status. The post-LTx group showed fewer decayed teeth (P = 0.03). A total of 86% of patients pre-LTx and 84% of patients post-LTx were found to need dental treatment, and 60% of patients pre-LTx and 55% of patients post-LTx showed a need for periodontal treatment. The prevalence of Candida albicans was high; however, there were no statistically significant differences between the groups in regard to fungal infection. CONCLUSION Improved dental care pre- and post-transplant, including screening for fungal infections, is recommended to avoid systemic infections in LTx patients. Increased attention to oral health care, and interdisciplinary collaboration to provide guidance, is needed to improve the oral health of patients before and after LTx.

Complex integrated analysis of lncRNAs-miRNAs-mRNAs in oral squamous cell carcinoma

OBJECTIVES This study aims to reveal regulatory network of lncRNAs-miRNAs-mRNAs in oral squamous cell carcinoma (OSCC) through gene expression data. MATERIAL AND METHODS Differentially expressed lncRNAs, miRNAs and mRNAs (cut-off: False discovery rate (FDR)<0.05 and |fold change|>1.5) were unveiled by package edgeR of R. Cox regression analysis was performed to screen prognostic factors in OSCC related with overall survival (OS) and relapse-free survival (RFS). Protein-protein interaction (PPI) network was constructed for differentially expressed mRNAs using BioGRID, HPRD and DIP. Key hub genes were identified from top 100 differentially expressed mRNAs ranked by betweenness centrality using recursive feature elimination. LncRNA-miRNA and miRNA-mRNA regulatory network were constructed and combined into ceRNAs regulatory network. Gene ontology biological terms and Kyoto Encyclopedia of Genes and Genomes pathways were identified using Fishers exact test. RESULTS A total of 929 differentially expressed mRNAs, 23 differentially expressed lncRNAs and 29 differentially expressed miRNAs were identified. 59 mRNAs, 6 miRNAs (hsa-mir-133a-1, hsa-mir-1-2, hsa-mir-486, hsa-mir-135b, hsa-mir-196b, hsa-mir-193b) and 6 lncRNAs (C10orf91, C2orf48, SFTA1P, FLJ41941,PART1,TTTY14) were related with OS; and 52 mRNAs, 4 miRNAs (hsa-mir-133a-1, hsa-mir-135b, hsa-mir-196b, hsa-mir-193b) and 2 lncRNAs (PART1, TTTY14) were associated with RFS. A support vector machine (SVM) classifier containing 37 key hub genes was obtained. A ceRNA regulatory network containing 417 nodes and 696 edges was constructed. ECM-receptor interaction, cytokine-cytokine receptor interaction, focal adhesion, arachidonic acid metabolism, and p53 signaling pathway were significantly enriched in the network. CONCLUSION These findings uncover the pathogenesis of OSCC and might provide potential therapeutic targets.

Oral health related quality of life depending on oral health and specific factors in patients after lung transplantation

Patients after lung transplantation (LuTx) were found to present oral health deficiencies. The investigation of potentially underlying or influencing factors appears to be of clinical relevance.

Microbiological and aMMP-8 findings depending on peri-implant disease in patients undergoing supportive implant therapy

The aim of this study was to evaluate microbiological findings and aMMP-8 level of peri-implant mucositis (M) and peri-implantitis (P) in patients undergoing supportive implant therapy (SIT). Eighty-nine patients with 171 implants were included. The case definitions were as follows: M: PPD ≥4mm, BOP; P: PPD≥4mm, BOP, radiographic bone loss ≥3.5mm. Samples of peri-implant sulcular fluid (PISF) were taken from all peri-implant pockets at each implant to detect periodontal pathogens using PCR and aMMP-8 level with ELISA. Only Treponema denticola (Td) and Prevotella intermedia (Pi) showed significantly higher prevalence in P (healthy implants [HI]: Td=27%, Pi=17%; M: Td=26%, Pi=15%; P: Td and Pi=50%; P<0.05). The mean aMMP-8 level at implant sites did not show any significant difference (P=0.05) among HI (5.2±8.1), M (9.9±19.0), and P (4.9±7.7). Microbiological findings and aMMP-8 levels are not reliable criteria to distinguish between HI, M, and P in patients undergoing SIT.

Periodontal condition is associated with disease duration and motoric disabilities in patients with ankylosing spondylitis: results of a cross-sectional study

ObjectiveRecent literature reveals worse periodontal health condition in ankylosing spondylitis (AS). However, roles of AS-related parameters, periodontal condition, and their association appear unclear. This cross-sectional study aimed at investigating dental and periodontal health as well as potentially periodontal pathogenic bacteria in patients with AS compared to healthy control subjects (HC).MethodsDental examination comprised dental findings (DMF-T), periodontal probing depth (PPD), bleeding on probing, clinical attachment loss (CAL), papillary bleeding index, and microbiological analysis based on polymerase chain reaction of selected potentially periodontal pathogenic bacteria. Classification of periodontitis severity was based on PPD and/or CAL and divided into no/mild, moderate, and severe periodontitis.Results52 participants with AS and 52 HC were included. 96% of the AS group and 75% of HC had moderate to severe periodontitis (moderate: AS = 26, HC = 34; severe: AS = 23, HC = 5; p < 0.01). Furthermore, a higher number of decayed teeth (D-T) were found in AS compared to HC (p = 0.02). A significant difference between AS und HC was detected for the prevalences of Parvimonas micra (AS = 92%, HC = 71%; p = 0.01), Eubacterium nodatum (AS = 35%, HC = 17%; p = 0.05), and Eikenella corrodens (AS = 96%, HC = 77%; p = 0.01). Bath Ankylosing Spondylitis Metrology Index (BASMI) and disease duration showed significant associations to PPD and CAL (p < 0.01).ConclusionPatients with AS show worse dental and periodontal conditions compared to HC. Thereby, prevalence of bacteria related to insufficient oral hygiene was higher in AS. BASMI and duration of AS affect periodontal burden. Accordingly, particular attention considering dental care and oral hygiene in AS patients seems to be reasonable.

Antimicrobial peptides as a possible interlink between periodontal diseases and its risk factors: A systematic review

Antimicrobial peptides (AMPs) play a critical role in controlling innate and acquired immune responses. Local dysregulation of AMP is implicated in the pathogenesis of periodontal diseases as a response to periodontal pathogen challenge. Changes in AMP expression also characterize tobacco smoking, diabetes mellitus, obesity and rheumatoid arthritis, which are established risk factors of periodontal diseases, suggesting AMP may act as putative mechanistic links between these. The aim was to evaluate and summarize critically the current evidence pertaining to interrelationships between AMPs, periodontal diseases and selected periodontal disease risk factors. General and theme specific keywords were used to search the PUBMED database for studies relevant to AMP, periodontal diseases, smoking, diabetes mellitus, obesity and rheumatoid arthritis and critically reviewed. A total of 131 abstracts and 119 full text articles were screened for relevance; 13 studies were selected for inclusion after critical review. Local AMP dysregulation characteristic to periodontal diseases appears to occur within a broader landscape of complex systemic immune perturbations independently induced by smoking, metabolic and rheumatoid disease. The nature of these interactions and mechanistic pathways involved are inadequately understood. AMPs could be possible mechanistic interlinks between periodontal diseases and its risk factors. However, such evidence is very limited and more in vivo and in vitro studies are necessary to clarify the nature of such relationships. A greater understanding of AMPs as shared mediators is essential for unraveling their value as therapeutic or biomarker candidates.

The impact of expert- and peer feedback on communication skills of undergraduate dental students – a single-blinded, randomized, controlled clinical trial

OBJECTIVE To evaluate the effect of peer- and expert feedback on communication skills of undergraduate dental students. METHODS All students of the first clinical treatment course (n=46) were randomly assigned into two groups. For three times a medical-dental interview/consultation of each student with a real patient was videotaped. After every consultation the videos were assessed either by a person experienced in communication (expert group) or by a fellow student (peer group), giving the students feedback regarding their chairside performed communication skills. Before and after the feedback-interventions all students conducted an interview with simulated patients, which was rated using a validated global rating and analyzed statistically. RESULTS Global ratings mean scores after feedback-intervention were significantly improved (p<0.05). Thereby, no significant differences in the overall assessment could be observed between expert and peer feedback (p>0.05). CONCLUSION During this study students improved their communication skills in dentist-patient interactions. The communication experience of the feedback provider seems not to have any impact on the communication skills in undergraduate dental students. PRACTICE IMPLICATIONS The clinical courses in dentistry offer the opportunity to implement peer-feedback interventions in real treatment situation as part of communication training to longitudinally improve communication skills.