Eminent science support from Jews to the young Turkish republic; a particular focus on dentistry.

During World War II, millions of people were mistreated and imprisoned in Nazi concentration camps. Due to the antisemitic pressure applied by the Nazi regime, many scientists had to leave Germany, and they immigrated to the United States, Switzerland, Turkey or South America. Alfred Kantorowicz was among those highly educated people who were forced out of their professional career. For a certain period, he had to stay away from the world of research and academia, which were his favorite occupations. However, these unexpected difficulties did not prevent him to pursue his success story with many awards, books, and scientific studies. Professor Kantorowicz was saved from a concentration camp upon the efforts of Mustafa Kemal Atatürk to modernize the university education system in Turkey. Prof. Kantorowicz worked from 1933 until his retirement in 1948 and acted as the "father of dentistry" in Turkey. His vision of preventive dentistry and his entrepreneurial approach should set an example for today's young dentists.

Cytotoxic impact of nicotine products on periodontal ligament cells.

OBJECTIVES: The primary objective of this in vitro experiment was an assessment of proliferative capacity, metabolic activity, and potential cellular detriment of human periodontal ligament cells (hPDL) exposed to cigarette smoke (CS), electronic cigarette vapor (eCV), and heated tobacco product aerosol (HTP), or air (control). MATERIALS AND METHODS: Using a CAD/CAM-designed exposition chamber, hPDL were exposed to CS, eCV, HTP, or air (control) based on the Health Canada Intense Smoking Regime. Cell proliferation, metabolic activity, and cellular detriment were assessed at various time points. RESULTS: Compared to the control, hPDL exposed to CS exhibited significantly decreased cell numbers at all time points. HTP exposure led to reduced cell numbers 48 h and 72 h post-exposure, while eCV-exposed cells showed no significant decrease. The metabolic activity of eCV-treated hPDL was slightly reduced at 7 h but recovered at 24 h and 48 h. In contrast, CS-treated cells exhibited significantly decreased metabolic activity at 24 h and 48 h, and HTP-exposed cells showed a significant decrease after 48 h. Flow cytometry indicated both apoptotic and necrotic cell death following CS exposure, with necrotic cell death being more pronounced. CONCLUSIONS: eCV and HTP demonstrated comparatively reduced detrimental effects on hPDL compared to CS. CLINICAL RELEVANCE: The findings suggest that conventional cigarette smoke poses a substantial risk to periodontal health by significantly impairing cell proliferation and metabolic activity. However, alternatives such as eCV and HTP may offer a comparatively reduced risk.

The working angle in low-abrasive air polishing has an influence on gingival damage-an ex vivo porcine model.

OBJECTIVES: To investigate the influence of instrumentation angle during low-abrasive air polishing (LAA) on the oral gingiva using an ex vivo porcine model. MATERIAL AND METHODS: Six tissue samples from each of 14 porcine mandibles were randomly selected and instrumented. Two different LAA powders (glycine 25 µm, tagatose 15 µm) were investigated. An application angle of either 30-60° or 90° was selected. Gingival specimens from different mandibles served as untreated references. Gingival biopsies were examined by scanning electron microscopy and paraffin histology for tissue destruction using a five-level scale. RESULTS: LAA caused significantly less tissue damage at a 90° angle than at a 30-60° angle. This effect was seen in both the glycine-based powder arms (p = 0.002, p = 0.046) and the tagatose-based powder arms (p = 0.003, p = 0.011). However, at identical working angles, the two powders did not show significant differences in terms of gingival erosion (p = 0.79 and p = 0.57; p = 0.91 and p = 0.78, respectively). CONCLUSIONS: LAA may cause less tissue damage at an application angle of 90°. Consequently, it seems advisable to air-polish the soft tissue as perpendicularly as possible. Additionally, glycine and tagatose LAA powders do not seem to differ in concern of soft tissue damage. CLINICAL RELEVANCE: Within the limitations of this ex vivo animal model, this study argues for an application that is as close as possible to the 90° angle intending to minimize soft tissue damage. Manufacturer specifications, however, mainly request applications deviating from the right angle. In order to work in interdental areas using LAA safely, the use of subgingival nozzles might be considered.

Gingival crevicular fluid levels of apelin correlates with clinical periodontal diagnosis.

OBJECTIVES: Limitations of clinical periodontal measurements have led to the search for reliable biomarkers that can be used in diagnosis and monitoring of periodontal diseases. Considering the relationship of adipokines with periodontal disease, diabetes, and obesity, apelin may be a biomarker for periodontal diseases due to its modulating effects on inflammation. The present study was conducted to determine gingival crevicular fluid (GCF) apelin levels in systemically healthy individuals and to evaluate the potential of apelin as a biomarker for periodontal diagnosis. MATERIALS AND METHODS: Ten individuals with clinically healthy periodontal tissues, 10 patients diagnosed with gingivitis, and 10 patients with periodontitis were included in the present study. Whole mouth clinical periodontal measurements were recorded and GCF samples were obtained from the buccal approximal regions of single-rooted teeth with features that would represent clinical periodontal diagnosis. Apelin level in the samples was determined by ELISA. Clinical and biochemical findings were statistically analyzed. Possible relationship between the variables was evaluated with Pearson correlation analysis. RESULTS: Apelin level in the gingivitis group was higher than that in the clinically healthy group (p = 0.000) and lower than that in the periodontitis group (p = 0.000). A positive correlation was found between GCF apelin concentration and plaque score, bleeding on probing, and probing depth (p = 0.000). CONCLUSIONS: Within the limits of this study, it can be suggested that GCF apelin concentration may be a biomarker that can distinguish between healthy periodontal tissues, gingivitis, and periodontitis patients. CLINICAL RELEVANCE: Apelin concentration in the gingival crevicular fluid may aid in the diagnosis of periodontal disease.

The impact of electronic and conventional cigarettes on periodontal health-a systematic review and meta-analysis.

OBJECTIVES: This systematic review and meta-analysis examined the effects of electronic cigarettes on periodontal health compared to conventional cigarette smoke and a non-smoking population. MATERIALS AND METHODS: MEDLINE, Embase, Web of Science, CENTRAL, and ClinicalTrials.gov were screened for literature. Eligibility criteria included clinical studies published between 2006 and 2022 that compare e-cigarettes and conventional cigarettes on periodontal health (bleeding on probing (BoP), plaque index (PI), probing depth (PD), attachment loss (AL), marginal bone loss (MBL), tooth loss, molecular inflammation markers, salivary flow rate). Meta-regression analysis was used to examine the influence of moderator variables. RESULTS: Sixteen studies were found to be eligible for qualitative synthesis. Individual analyses showed that cigarette smokers had significantly higher PI, PD, AL, and MBL and increased concentrations of proinflammatory mediators than e-cigarette users and non-smokers. Meta-analysis revealed a 0.33-fold lower chance for BoP in e-cigarette users compared to smokers (p = 0.03), whereby meta-regression failed to detect any effects regarding the age of users and frequency of smoking. A 0.01-fold decreased chance for positive BoP in e-cigarette users compared with non-smokers was seen (p < 0.01). CONCLUSIONS: The current findings suggest that that e-cigarette use might be considered a healthier alternative to cigarette smoking concerning periodontal health. Even so, harmful effects of electronic nicotine delivery system (ENDS) usage on periodontal health were seen as well. However, a definitive decision on this research question remains elusive due to the absence of randomized controlled trials. CLINICAL RELEVANCE: Electronic cigarettes, marketed as a safer alternative to traditional cigarettes, are becoming increasingly popular. Evidence on the use of electronic cigarettes as a cessation aid and its beneficial impact compared to cigarette smoke remains inconclusive, so the analysis conducted in this review addresses a recent question of high clinical relevance.

Dental Pulp Inflammation Initiates the Occurrence of Mast Cells Expressing the α1 and ß1 Subunits of Soluble Guanylyl Cyclase.

The binding of nitric oxide (NO) to heme in the ß1 subunit of soluble guanylyl cyclase (sGC) activates both the heterodimeric α1ß1 and α2ß1 isoforms of the enzyme, leading to the increased production of cGMP from GTP. In cultured human mast cells, exogenous NO is able to inhibit mast cell degranulation via NO-cGMP signaling. However, under inflammatory oxidative or nitrosative stress, sGC becomes insensitive to NO. The occurrence of mast cells in healthy and inflamed human tissues and the in vivo expression of the α1 and ß1 subunits of sGC in human mast cells during inflammation remain largely unresolved and were investigated here. Using peroxidase and double immunohistochemical incubations, no mast cells were found in healthy dental pulp, whereas the inflammation of dental pulp initiated the occurrence of several mast cells expressing the α1 and ß1 subunits of sGC. Since inflammation-induced oxidative and nitrosative stress oxidizes Fe2+ to Fe3+ in the ß1 subunit of sGC, leading to the desensitization of sGC to NO, we hypothesize that the NO- and heme-independent pharmacological activation of sGC in mast cells may be considered as a regulatory strategy for mast cell functions in inflamed human dental pulp.

Effectiveness and Safety of Over-the-Counter Tooth-Whitening Agents Compared to Hydrogen Peroxide In Vitro.

(1) This study investigated the whitening effect, cytotoxicity and enamel surface alterations induced by different over-the-counter (OTC) bleaching agents in comparison to hydrogen peroxide. (2) Human teeth (n = 60) were randomly assigned into 6 groups (n = 10), stained with coffee solution for 7 d, followed by a whitening period of 7 d with either placebo, bromelain, sodium bicarbonate, sodium chlorite, PAP or hydrogen peroxide. Color measurements were performed with a spectrophotometer. Scanning electron micrographs (SEM) were taken to assess the enamel structure. Cytotoxicity of the tested substances was assessed based on the cell viability of primary human fibroblasts. (3) The application of all whitening gels resulted in a greater color difference of the enamel (ΔE) in comparison to the negative control. Hydrogen peroxide caused the greatest color difference. Bromelain and PAP treatment showed no enamel surface changes, in contrast to hydrogen peroxide treatment, which showed very mild interprismatic dissolution. Bromelain was the only non-cytotoxic agent. (4) The maximum effect achieved by all OTC bleaching agents was the removal of stains, whereas hydrogen peroxide was capable of further whitening the teeth. Bromelain treatment was neither cytotoxic, nor resulted in enamel surface alterations, and its whitening effect was less, yet still effective, compared to hydrogen peroxide.

Influence of Occlusal Hypofunction on Alveolar Bone Healing in Rats.

The aim of this in vivo study was to investigate the effect of occlusal hypofunction on alveolar bone healing in the absence or presence of an enamel matrix derivative (EMD). A standardized fenestration defect over the root of the mandibular first molar in 15 Wistar rats was created. Occlusal hypofunction was induced by extraction of the antagonist. Regenerative therapy was performed by applying EMD to the fenestration defect. The following three groups were established: (a) normal occlusion without EMD treatment, (b) occlusal hypofunction without EMD treatment, and (c) occlusal hypofunction with EMD treatment. After four weeks, all animals were sacrificed, and histological (hematoxylin and eosin, tartrate-resistant acid phosphatase) as well as immunohistochemical analyses (periostin, osteopontin, osteocalcin) were performed. The occlusal hypofunction group showed delayed bone regeneration compared to the group with normal occlusion. The application of EMD could partially, but not completely, compensate for the inhibitory effects of occlusal hypofunction on bone healing, as evidenced by hematoxylin and eosin and immunohistochemistry for the aforementioned molecules. Our results suggest that normal occlusal loading, but not occlusal hypofunction, is beneficial to alveolar bone healing. Adequate occlusal loading appears to be as advantageous for alveolar bone healing as the regenerative potential of EMD.

Apelin Enhances the Effects of Fusobacterium nucleatum on Periodontal Ligament Cells In Vitro.

This study aimed to explore effects of Fusobacterium nucleatum with or without apelin on periodontal ligament (PDL) cells to better understand pathomechanistic links between periodontitis and obesity. First, the actions of F. nucleatum on COX2, CCL2, and MMP1 expressions were assessed. Subsequently, PDL cells were incubated with F. nucleatum in the presence and absence of apelin to study the modulatory effects of this adipokine on molecules related to inflammation and hard and soft tissue turnover. Regulation of apelin and its receptor (APJ) by F. nucleatum was also studied. F. nucleatum resulted in elevated COX2, CCL2, and MMP1 expressions in a dose- and time-dependent manner. Combination of F. nucleatum and apelin led to the highest (p < 0.05) expression levels of COX2, CCL2, CXCL8, TNF-α, and MMP1 at 48 h. The effects of F. nucleatum and/or apelin on CCL2 and MMP1 were MEK1/2- and partially NF-κB-dependent. The combined effects of F. nucleatum and apelin on CCL2 and MMP1 were also observed at protein level. Moreover, F. nucleatum downregulated (p < 0.05) the apelin and APJ expressions. In conclusion, obesity could contribute to periodontitis through apelin. The local production of apelin/APJ in PDL cells also suggests a role of these molecules in the pathogenesis of periodontitis.

Non-Invasive Physical Plasma Reduces the Inflammatory Response in Microbially Prestimulated Human Gingival Fibroblasts.

Non-invasive physical plasma (NIPP), an electrically conductive gas, is playing an increasingly important role in medicine due to its antimicrobial and regenerative properties. However, NIPP is not yet well established in dentistry, although it has promising potential, especially for periodontological applications. The aim of the present study was to investigate the effect of NIPP on a commercially available human gingival fibroblast (HGF) cell line and primary HGFs in the presence of periodontitis-associated bacteria. First, primary HGFs from eight patients were characterised by immunofluorescence, and cell numbers were examined by an automatic cell counter over 5 days. Then, HGFs that were preincubated with Fusobacterium nucleatum (F.n.) were treated with NIPP. Afterwards, the IL-6 and IL-8 levels in the cell supernatants were determined by ELISA. In HGFs, F.n. caused a significant increase in IL-6 and IL-8, and this F.n.-induced upregulation of both cytokines was counteracted by NIPP, suggesting a beneficial effect of physical plasma on periodontal cells in a microbial environment. The application of NIPP in periodontal therapy could therefore represent a novel and promising strategy and deserves further investigation.

Obesity Modifies the Proteomic Profile of the Periodontal Ligament.

This study aimed to assess the obesity effects on the proteomic profile of the periodontal ligament of rats submitted to obesity induction by a high-fat diet. Eight Holtzman rats were divided into control (n = 3) and obese (n = 5) groups. The maxillae were histologically processed for laser capture microdissection of the periodontal ligament of the first maxillary molars. Peptide mixtures were analyzed by LC-MS/MS. A total of 1379 proteins were identified in all groups. Among them, 335 (24.30%) were exclusively detected in the obese group, while 129 (9.35%) proteins were uniquely found in the control group. Out of the 110 (7.98%) differentially abundant proteins, 10 were more abundant and 100 had decreased abundance in the obese group. A gene ontology analysis showed some proteins related to obesity in the "extracellular exosome" term among differentially identified proteins in the gene ontology cellular component terms Prelp, Sec13, and Sod2. These three proteins were upregulated in the obese group (p < 0.05), as shown by proteomic and immunohistochemistry analyses. In summary, our study presents novel evidence that the proteomic profile of the periodontal ligament is altered in experimental obesity induction, providing a list of differentially abundant proteins associated with obesity, which indicates that the periodontal ligament is responsive to obesity.

Oxygen-Releasing Hyaluronic Acid-Based Dispersion with Controlled Oxygen Delivery for Enhanced Periodontal Tissue Engineering.

Periodontitis is a chronic biofilm-associated inflammatory disease of the tooth-supporting tissues that causes tooth loss. It is strongly associated with anaerobic bacterial colonization and represents a substantial global health burden. Due to a local hypoxic environment, tissue regeneration is impaired. Oxygen therapy has shown promising results as a potential treatment of periodontitis, but so far, local oxygen delivery remains a key technical challenge. An oxygen (O2)-releasing hyaluronic acid (HA)-based dispersion with a controlled oxygen delivery was developed. Cell viability of primary human fibroblasts, osteoblasts, and HUVECs was demonstrated, and biocompatibility was tested using a chorioallantoic membrane assay (CAM assay). Suppression of anaerobic growth of Porphyromonas gingivalis was shown using the broth microdilution assay. In vitro assays showed that the O2-releasing HA was not cytotoxic towards human primary fibroblasts, osteoblasts, and HUVECs. In vivo, angiogenesis was enhanced in a CAM assay, although not to a statistically significant degree. Growth of P. gingivalis was inhibited by CaO2 concentrations higher than 256 mg/L. Taken together, the results of this study demonstrate the biocompatibility and selective antimicrobial activity against P. gingivalis for the developed O2-releasing HA-based dispersion and the potential of O2-releasing biomaterials for periodontal tissue regeneration.

Obesity influences the proteome of periodontal ligament tissues following periodontitis induction in rats.

BACKGROUND AND OBJECTIVES: Many studies have been conducted to better understand the molecular mechanism involved with periodontitis progression. There has been growing interest in the potential impact of obesity on periodontitis onset and progression, but the mechanisms involved remain to be elucidated. The present study was designed to determine the impact of obesity on experimentally induced periodontitis in rats and identify novel pathways involved. METHODS: Sixteen Holtzman rats were distributed into two groups (n = 8): ligature-induced periodontitis (P) and obesity plus ligature-induced periodontitis (OP). Obesity was induced by a high-fat diet for 70 days, whereas periodontitis was induced for 20 days, with a cotton thread placed around the upper first molars bilaterally. Alveolar bone loss was measured by microtomographic analysis and histologically by histometry on the hemimaxillae. The protein composition of the periodontal ligament was evaluated by proteomic analysis. RESULTS: Data analysis (body weight, adipose tissue weight, and blood test) confirmed obesity induction, whereas bone loss was confirmed by micro-CT and histologic analyses. Proteome analysis from the periodontal ligament tissues (PDL) identified 819 proteins, 53 exclusive to the P group, 28 exclusive to the OP group, and 738 commonly expressed. Validation was performed by immunohistochemistry for selected proteins (spondin1, vinculin, and TRAP). CONCLUSION: Histologically, it was found that obesity did not significantly affect bone loss resulting from periodontitis. However, the present study's findings indicated that obesity affects the proteome of PDL submitted to experimental periodontitis, allowing for identifying potential targets for personalized approaches.

Cellular effects of glycine and trehalose air-polishing powders on human gingival fibroblasts in vitro.

OBJECTIVES: Air-polishing has been used in the treatment of periodontitis and gingivitis for years. The introduction of low-abrasive powders has enabled the use of air-polishing devices for subgingival therapy. Within the last decade, a wide range of different low-abrasive powders for subgingival use has been established. In this study, the effects of a glycine powder and a trehalose powder on human gingival fibroblasts (HGF) were investigated. METHODS: HGF were derived from three systemically and periodontally healthy donors. After 24 h and 48 h of incubation time, mRNA levels, and after 48 h, protein levels of TNFα, IL-8, CCL2, and VEGF were determined. In addition, NF-κB p65 nuclear translocation and in vitro wound healing were assessed. Statistical analysis was performed by ANOVA and post hoc Dunnett's and Tukey's tests (p < 0.05). RESULTS: Glycine powder significantly increased the expression of proinflammatory genes and showed exploitation of the NF-κB pathway, albeit trehalose powder hardly interfered with cell function and did not trigger the NF-κB pathway. In contrast to trehalose, glycine showed a significant inhibitory effect on the in vitro wound healing rate. CONCLUSION: Subgingivally applicable powders for air-polishing devices can regulate cell viability and proliferation as well as cytokine expression. Our in vitro study suggests that the above powders may influence HGF via direct cell effects. Trehalose appears to be relatively inert compared to glycine powder. CLINICAL RELEVANCE: With the limitations of an in vitro design, our study suggests that in terms of cell response, trehalose-based air-polishing powders show a reduced effect on inflammation.

Influence of cold atmospheric plasma on dental implant materials - an in vitro analysis.

BACKGROUND AND OBJECTIVES: Alterations in the microenvironment of implant surfaces could influence the cellular crosstalk and adhesion patterns of dental implant materials. Cold plasma has been described to have an influence on cells, tissues, and biomaterials. Hence, the mechanisms of osseointegration may be altered by non-thermal plasma treatment depending on different chemical compositions and surface coatings of the biomaterial. The aim of the present study is to investigate the influence of cold atmospheric plasma (CAP) treatment on implant surfaces and its biological and physicochemical side effects. MATERIALS AND METHODS: Dental implant discs from titanium and zirconia with different surface modifications were treated with CAP at various durations. Cell behavior and adhesion patterns of human gingival fibroblast (HGF-1) and osteoblast-like cells (MG-63) were examined using scanning electron microscopy and fluorescence microscopy. Surface chemical characterization was analyzed using energy-dispersive X-ray spectroscopy (EDS). Quantitative analysis of cell adhesion, proliferation, and extracellular matrix formation was conducted including real-time PCR. RESULTS: CAP did not affect the elemental composition of different dental implant materials. Additionally, markers for cell proliferation, extracellular matrix formation, and cell adhesion were differently regulated depending on the application time of CAP treatment in MG-63 cells and gingival fibroblasts. CONCLUSIONS: CAP application is beneficial for dental implant materials to allow for faster proliferation and adhesion of cells from the surrounding tissue on both titanium and zirconia implant surfaces with different surface properties. CLINICAL RELEVANCE: The healing capacity provided through CAP treatment could enhance osseointegration of dental implants and has the potential to serve as an effective treatment option in periimplantitis therapy.

Interaction of periodontitis and orthodontic tooth movement-an in vitro and in vivo study.

OBJECTIVES: The aim of this in vitro and in vivo study was to investigate the interaction of periodontitis and orthodontic tooth movement on interleukin (IL)-6 and C-X-C motif chemokine 2 (CXCL2). MATERIALS AND METHODS: The effect of periodontitis and/or orthodontic tooth movement (OTM) on alveolar bone and gingival IL-6 and CXCL2 expressions was studied in rats by histology and RT-PCR, respectively. The animals were assigned to four groups (control, periodontitis, OTM, and combination of periodontitis and OTM). The IL-6 and CXCL2 levels were also studied in human gingival biopsies from periodontally healthy and periodontitis subjects by RT-PCR and immunohistochemistry. Additionally, the synthesis of IL-6 and CXCL2 in response to the periodontopathogen Fusobacterium nucleatum and/or mechanical strain was studied in periodontal fibroblasts by RT-PCR and ELISA. RESULTS: Periodontitis caused an increase in gingival levels of IL-6 and CXCL2 in the animal model. Moreover, orthodontic tooth movement further enhanced the bacteria-induced periodontal destruction and gingival IL-6 gene expression. Elevated IL-6 and CXCL2 gingival levels were also found in human periodontitis. Furthermore, mechanical strain increased the stimulatory effect of F. nucleatum on IL-6 protein in vitro. CONCLUSIONS: Our study suggests that orthodontic tooth movement can enhance bacteria-induced periodontal inflammation and thus destruction and that IL-6 may play a pivotal role in this process. CLINICAL RELEVANCE: Orthodontic tooth movement should only be performed after periodontal therapy. In case of periodontitis relapse, orthodontic therapy should be suspended until the periodontal inflammation has been successfully treated and thus the periodontal disease is controlled again.

Frequency of the necessity of dentoalveolar surgery or conservative treatment in patients before kidney transplantation depending on the duration of dialysis and causative nephrological disease.

OBJECTIVES: This retrospective study evaluates intraoral surgical and conservative treatment need in patients with a chronic kidney end-stage disease, depending on the duration of dialysis treatment and the causative nephrological disease. MATERIAL AND METHODS: This study is based on data of patients referred to the Department of Oral and Maxillofacial Surgery of the University Hospital Erlangen, Germany, prior to kidney transplantation between January 2015 and March 2020. The necessity for oral surgical or dental therapy was determined by clinical and radiological examinations. Data on renal replacement therapy, cause of underlying renal disease, lifestyle, and general health were collected. RESULTS: Data of N = 89 patients demonstrated that surgical treatment need depends on dialysis duration (p = 0.042). Patients, who had been dialyzing for 2 to 3 years showed the highest need for surgical intervention (80.0%; p = 0.024), followed by dialysis patients with a dialysis time of more than 3 years (48.1%). Similarly, dialysis patients in the second or third year of dialysis had the highest need for conservative treatment (73.3%; p > 0.05), followed by 55.6% of dialysis patients in the third year of dialysis. CONCLUSIONS: Operative and conservative treatment is essential to optimize subsequent kidney transplantation. The greatest necessity could be detected for patients in the second and third years of dialysis. CLINICAL RELEVANCE: Oral health addressing surgical and conservative treatment need depends on the duration of dialysis in patients with a chronic kidney end-stage disease.

Effect of Bacterial Infection on Ghrelin Receptor Regulation in Periodontal Cells and Tissues.

The effect of bacterial infection on the expression of growth hormone secretagogue receptor (GHS-R) was investigated in periodontal cells and tissues, and the actions of ghrelin were evaluated. GHS-R was assessed in periodontal tissues of rats with and without periodontitis. Human gingival fibroblasts (HGFs) were exposed to Fusobacterium nucleatum in the presence and absence of ghrelin. GHS-R expression was determined by real-time PCR and immunocytochemistry. Furthermore, wound healing, cell viability, proliferation, and migration were evaluated. GHS-R expression was significantly higher at periodontitis sites as compared to healthy sites in rat tissues. F. nucleatum significantly increased the GHS-R expression and protein level in HGFs. Moreover, ghrelin significantly abrogated the stimulatory effects of F. nucleatum on CCL2 and IL-6 expressions in HGFs and did not affect cell viability and proliferation significantly. Ghrelin stimulated while F. nucleatum decreased wound closure, probably due to reduced cell migration. Our results show original evidence that bacterial infection upregulates GHS-R in rat periodontal tissues and HGFs. Moreover, our study shows that ghrelin inhibited the proinflammatory actions of F. nucleatum on HGFs without interfering with cell viability and proliferation, suggesting that ghrelin and its receptor may act as a protective molecule during bacterial infection on periodontal cells.

Impact of melatonin on periodontal ligament fibroblasts during mechanical strain.

BACKGROUND: The endogenous hormone melatonin regulates the circadian rhythm and impacts on bone metabolism. As patient compliance to wear removable orthodontic appliances is generally higher at night, when melatonin release is increased, a boosting effect on tooth movement would be favourable for therapy, whereas an inhibiting effect would indicate daytime wear to be more therapy-effective. We hypothesize that melatonin has either a stimulating or impeding effect on the expression profile of periodontal ligament fibroblasts (PDLF) during simulated orthodontic compressive and tensile strain, which would suggest either an accelerating or inhibiting impact on orthodontic tooth movement in vivo. METHODS: PDLF were preincubated with melatonin for 24 h and then subjected to tensile or compressive strain to mimic tension and pressure sides in PDL. In addition, the selective melatonin MTNR1B-receptor antagonist 4P-PDOT was used. We investigated melatonin effects on collagen synthesis, expression of inflammatory and bone-remodelling genes/proteins by quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assays, and total collagen assays. PDLF-induced osteoclastogenesis was analysed in a coculture model by tartrate-resistant acid phosphatise (TRAP) staining. RESULTS: Expression of melatonin receptors in PDLF was not affected by compressive strain. Melatonin increased expression of inflammatory factors and elevated collagen synthesis during mechanical strain. Melatonin showed no effects on OPG or RANKL expression without mechanical strain, but increased RANKL gene expression during compression. CONCLUSIONS: Expression of melatonin receptors by PDLF enable them to detect fluctuating melatonin concentrations in the periodontal ligament. Melatonin increased collagen synthesis and expression of inflammatory mediators, but had no effect on genes involved in bone remodelling. Therefore, we suggest that melatonin has no accelerating effect on PDLF-induced osteoclastogenesis.

Interplay of pandemic and seasonal parameters in dental emergency service.

BACKGROUND: To evaluate the relationship between pandemic events and dental emergency service frequentation. Utilization patterns in the scope of the COVID-19 pandemic were analyzed and considered in regard of seasonal parameters. METHODS: All outpatients seeking treatment in a university hospital's dental emergency service were analyzed in the years 2019, 2019 and 2020 according to demographic data and emergencies were subdivided into "absolute" and "relative". The years 2018 and 2019 were used to compare COVID-19 and non-COVID-19 phases. Defined waves of the pandemic were compared with equivalent prior-year periods. RESULTS: Our study includes 11,219 dental emergency patients over a period of three years with a slight surplus of male patients. Comparing the pre-COVID-19 years and 2020 as a year of pandemic, the total count of cases decreased by more than 25%. The share of absolute emergencies in 2020 was higher than in the years before (p < 0.0001). The under-utilization during the waves was more pronounced during the first wave compared to the second waves. CONCLUSIONS: Additionally to the clear decrease by more than 25% in 2020, we found an inverse dependency of 7-day-incidence of COVID-19 and number of visits. This effect was more distinct for relative emergencies, while the number of patients with absolute emergencies remains rather constant. Probably, there is an acclimatization effect regarding the waves. Patients older than 60 years who suffered from relative emergencies showed an under-utilzation during 2020. During a pandemic such as COVID-19, the effect of under-utilization is more pronounced among elderly patients. However, a pandemic acclimatization effect seems to occur. This can be taken into account in the administration of this kind of circumstances in the future.