Publications by authors named "Knut Adam"

5 Publications

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Application of the inverted classroom model in the teaching module "new classification of periodontal and peri-implant diseases and conditions" during the COVID-19 pandemic.

GMS J Med Educ 2021;38(5):Doc89. Epub 2021 Jun 15.

Hannover Medical School, Department of Conservative Dentistry, Periodontology and Preventive Dentistry, Hannover, Germany.

Due to the need for patient-free dental education during the COVID-19 pandemic, Hannover Medical School (MHH) implemented a new periodontology module. Its didactic structure was based on the "inverted classroom model" (ICM) in combination with elements of case-based learning. The educational objective was to increase the diagnostic confidence of dental students in the classification of periodontal patients (staging & grading), based on 33 digitized patient cases. To assess the suitability of the module for future dental curricula, this study aimed to evaluate student satisfaction and skills acquisition. The periodontology module, which was attended by final year dental students of MHH (n=55, mean age: 26.5±3.9 years, male/female ratio: 24.1%/75.9%) was evaluated in a two-tiered way. Student satisfaction was recorded using a questionnaire. Learning success was assessed by comparing error rates in patient case classifications before (T) and after (T) participation in the periodontology module. The study found a high level of student satisfaction with the ICM format and a significant reduction in error rates (T error rate=28.3%; MV±SD=3.12±1.67 vs. T error rate=18.7%; MV±SD=2.06±1.81; Δ=9.6%). However, of the 11 diagnostic decisions required, only four parameters (extent, grading, percentage of bone loss per age, phenotype) showed significant improvements, with effect sizes ranging from small to medium. The ICM-based teaching concept is definitely not an alternative to patient-based learning. However, in regard to student satisfaction and learning success, it might be superior to conventional classroom-based lectures, especially when complex topics are covered. In summary, the newly developed periodontology module may be a useful addition to traditional dental education in future curricula, even for the time after the COVID-19 pandemic.
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June 2021

Evaluation of stemness properties of cells derived from granulation tissue of peri-implantitis lesions.

Clin Exp Dent Res 2021 Feb 18. Epub 2021 Feb 18.

Department of Conservative Dentistry, Periodontology & Preventive Dentistry, School of Dentistry, Hannover Medical School (MHH), Hannover, Germany.

Objectives: Peri-implantitis (PI) is an inflammatory disease associated with peri-implant bone loss and impaired healing potential. There is limited evidence about the presence of mesenchymal stromal cells (MSCs) and their regenerative properties within the granulation tissue (GT) of infrabony peri-implantitis defects. The aim of the present study was to characterize the cells derived from the GT of infrabony PI lesions (peri-implantitis derived mesenchymal stromal cells-PIMSCs).

Material And Methods: PIMSC cultures were established from GT harvested from PI lesions with a pocket probing depth ≥6 mm, bleeding on probing/suppuration, and radiographic evidence of an infrabony component from four systemically healthy individuals. Cultures were analyzed for embryonic (SSEA4, NANOG, SOX2, OCT4A), mesenchymal (CD90, CD73, CD105, CD146, STRO1) and hematopoietic (CD34, CD45) stem cell markers using flow cytometry. PIMSC cultures were induced for neurogenic, angiogenic and osteogenic differentiation by respective media. Cultures were analyzed for morphological changes and mineralization potential (Alizarin Red S method). Gene expression of neurogenic (NEFL, NCAM1, TUBB3, ENO2), angiogenic (VEGFR1, VEGFR2, PECAM1) and osteogenic (ALPL, BGLAP, BMP2, RUNX2) markers was determined by quantitative RT-PCR.

Results: PIMSC cultures demonstrated high expression of embryonic and mesenchymal stem cell markers with inter-individual variability. After exposure to neurogenic, angiogenic and osteogenic conditions, PIMSCs showed pronounced tri-lineage differentiation potential, as evidenced by their morphology and expression of respective markers. High mineralization potential was observed.

Conclusions: This study provides evidence that MSC-like populations reside within the GT of PI lesions and exhibit a multilineage differentiation potential. Further studies are needed to specify the biological role of these cells in the healing processes of inflamed PI tissues and to provide indications for their potential use in regenerative therapies.
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February 2021

Root coverage using a connective tissue graft with epithelial striation in combination with enamel matrix derivatives - a long-term retrospective clinical interventional study.

BMC Oral Health 2019 07 15;19(1):148. Epub 2019 Jul 15.

Department of Conservative Dentistry, Periodontology and Preventive Dentistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.

Background: The application of a connective tissue graft with epithelial striation (CTG-ES) has been shown to improve the outcome of root coverage (RC) using the coronally advanced flap (CAF) and adjunctive administration of enamel matrix derivatives (EMD). Aim of the present study was to evaluate the long-term (mean: 16.19 ± 1.80 years, range: 13 to 18 years) stability of this treatment method with special focus on the location of the gingival margin and the width of keratinized tissue (WKT).

Methods: 16 patients (10 female, 6 male, aged 35.36 ± 14.70 years at surgery) with 25 Miller class I or II gingival recession (GR) defects were treated using the CAF combined with the CTG-ES and EMD. The clinical measurements recorded at baseline (t0), 6 months (t1), and 13 to 18 years (t2) after surgery included recession depth (RED), probing pocket depth (PPD), clinical attachment level (CAL), and WKT. In addition, the number of sites with complete RC (CRC) and the mean RC (MRC) were documented at t1 and t2. The statistical analysis was performed using a linear mixed model.

Results: The RED (t0: 4.52 ± 1.56 mm; t1: 0.36 ± 0.76 mm; t2: 0.30 ± 0.60 mm) and CAL (t0: 6.16 ± 1.62 mm; t1: 1.86 ± 0.87 mm; t2: 1.54 ± 0.92 mm) were significantly reduced at t1 and t2 compared to t0 (p <  0.001). The PPD was significantly reduced at t2 compared to t0 (p = 0.016). The WKT (t0: 1.18 ± 1.28 mm; t1: 3.26 ± 0.98 mm; t2: 4.26 ± 1.83 mm) significantly increased from t0 to t1, from t0 to t2 (p <  0.001) and from t1 to t2 (p = 0.007). A CRC was recorded at 19 sites (76.0%) at t1 and t2. The MRC was 93.6 ± 12.8% at t1 and 93.3 ± 13.3% at t2.

Conclusions: The use of the CAF combined with CTG-ES and EMD leads to stable long-term outcomes on teeth with Miller Class I or II GR defects. The CTG-ES represents a hybrid graft with increased position stability and advantageous properties for the healing process. We assume that the ES is responsible for the increase of the WKT.
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July 2019

Impaired angiogenic differentiation of dental pulp stem cells during exposure to the resinous monomer triethylene glycol dimethacrylate.

Dent Mater 2019 01 28;35(1):144-155. Epub 2018 Nov 28.

Department of Conservative Dentistry, Periodontology and Preventive Dentistry, Hannover Medical School, D-30625 Hannover, Germany. Electronic address:

Objective: Dental pulp stem cells (DPSCs) can differentiate into tissue specific lineages to support dental pulp regeneration after injuries. Triethylene glycol dimethacrylate (TEGDMA) is a widely used co-monomer in restorative dentistry with adverse effects on cellular metabolism. Aim of this study was to analyze the impact of TEGDMA on the angiogenic differentiation potential of DPSCs.

Methods: DPSCs were characterized by flow cytometry. Short-term (max. 72h) cytotoxicity of TEGDMA was assessed by MTT assay. To evaluate TEGDMA effects on angiogenic differentiation, DPSCs were cultivated in angiogenic differentiation medium (ADM) in the presence or absence of short-term non-toxic TEGDMA concentrations (0.1mM and 0.25mM). Subsequently, angiogenic differentiation was analyzed by qRT-PCR analysis of mRNA markers and in vitro spheroid sprouting assays.

Results: DPSCs treated with 0.25mM TEGDMA revealed downregulation of angiogenesis-related marker genes PECAM1 (max. 3.8-fold), VEGF-A (max. 2.4-fold) and FLT1 (max. 2.9-fold) compared to respective untreated control. In addition, a reduction of the sprouting potential of DPSCs cultured in the presence of 0.25mM TEGDMA was detectable. Larger spheroidal structures were detectable in the untreated control in comparison to cells treated with 0.25mM TEGDMA. In contrast, TEGDMA at 0.1mM was not affecting angiogenic potential in the investigated time period (up to 28 days).

Significance: The results of the present study show that TEGDMA concentration dependently impair the angiogenic differentiation potential of DPSCs and may affect wound healing and the formation of granulation tissue.
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January 2019

A haplotype block downstream of plasminogen is associated with chronic and aggressive periodontitis.

J Clin Periodontol 2017 Oct 11;44(10):962-970. Epub 2017 Sep 11.

Department of Periodontology, Institute of Dental, Oral and Maxillary Medicine, Charité - University Medicine Berlin, Berlin, Germany.

Aim: The intronic variant rs4252120 in the plasminogen gene (PLG) is known to be associated with aggressive periodontitis (AgP) and atherosclerosis. Here, we examined the chromosomal region spanning PLG for associations with both chronic periodontitis (CP) and AgP.

Materials And Methods: The association of PLG candidate rs4252120 was tested in a German case-control sample of 1,419 CP cases using the genotyping assay hCV11225947 and 4,562 controls, genotyped with HumanOmni BeadChips. The German and Dutch sample of AgP cases (N = 851) and controls (N = 6,836) were genotyped with HumanOmni BeadChips. The North American CP sample (N = 2,681 cases, 1,823 controls) was previously genotyped on the Genome-Wide Human SNP Array 6.0. Genotypes were imputed (software Impute v2), and association tests were performed using an additive genetic model adjusting for sex and smoking.

Results: Rs4252120 was not associated with CP. However, a haplotype block downstream of PLG and not in linkage disequilibrium with rs4252120 (r = .08) was associated with both AgP (rs1247559; p = .002, odds ratio [OR] = 1.33) and CP (p = .02, OR = 1.15). That locus was also significantly associated with PLG expression in osteoblasts (p = 6.9 × 10 ).

Conclusions: Our findings support a role of genetic variants in PLG in the aetiology of periodontitis.
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October 2017