Developmental endothelial locus-1 promotes osteogenic differentiation and alveolar bone regeneration in experimental periodontitis with type 2 diabetes mellitus.

OBJECTIVES: This study sought to explore the role of developmental endothelial locus-1 (DEL-1) in osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and investigate the therapeutic effect of DEL-1 in ligature-induced experimental periodontitis with type 2 diabetes mellitus (T2DM). BACKGROUND: T2DM is a significant risk factor for periodontitis. Treatment modalities for periodontitis with T2DM are being explored. DEL-1 is a versatile protein that can modulate the different stages of inflammatory diseases including periodontitis. The direct effect of DEL-1 on osteogenic differentiation of PDLSCs in periodontitis with T2DM is poorly understood. METHODS: Primary hPDLSCs were isolated from periodontal ligament tissue and identified by flow cytometry. In osteogenesis experiments, alkaline phosphatase (ALP), Alizarin Red staining and western blot were used to assess the osteogenic effect of DEL-1 on hPDLSCs in high glucose and inflammation environments. The mouse model of ligature-induced experimental periodontitis was established. H&E and Masson's trichrome staining were used to assess the change of periodontal tissue after local periodontal injection of DEL-1. Immunohistochemical staining was used to evaluate osteogenic-related protein expression. RESULTS: hPDLSCs expressed mesenchymal stem cell (MSC)-specific surface markers and were negative for hematopoietic cell surface markers. hPDLSCs had the potential for multidirectional differentiation. DEL-1 could enhance the osteogenic differentiation of hPDLSCs in high glucose and inflammation environments, although it did not return to the control level. Histological staining showed that DEL-1 contributed to alveolar bone regeneration and osteogenic-related protein expression, but the degree of improvement in T2DM mice was lower than in non-T2DM mice. CONCLUSIONS: In summary, we demonstrated that DEL-1 could promote osteogenic differentiation of hPDLSCs in high glucose and inflammation environment and rescue alveolar bone loss in experimental periodontitis with T2DM, which could provide a novel therapeutic target for periodontitis with T2DM.

Comparison of flash-free and conventional bonding systems: A systematic review and meta-analysis.

OBJECTIVES: To review the literature systematically to compare the performance of adhesive precoated flash-free bonding systems with conventional adhesive precoated (APC) and operator-coated (OPC) bonding systems. MATERIALS AND METHODS: PubMed, Cochrane Library, Web of Science, and Embase were searched for potential eligible studies. Study selection and data collection were conducted independently. Statistical analysis was performed by Review Manager 5.3. The Cochran Q test was used to test heterogeneity in the included studies. Risk of bias was evaluated using Cochrane RoB 2.0 tool for randomized controlled trials. RESULTS: Six studies were included and the overall risk-of-bias judgment was low risk of bias to some concerns. The results of the meta-analyses showed that flash-free required significantly less bonding time than APC (mean difference [MD]: -1.56; 95% confidence intervals [CIs]: -2.56 to -0.56), and no significant differences were found in bond failure rates (risk ratio [RR]: 1.54; 95% Cis: 0.27 to 8.89) and adhesive remnant index (ARI) (MD: -0.50; 95% CIs: -1.14 to 0.14) between them. Qualitative analysis showed that flash-free might have a positive effect on enamel demineralization compared to APC but the quantity of plaque did not differ between them. CONCLUSIONS: The flash-free bonding system significantly reduced bonding time and it had comparable bond failure rates with APC. So far, there is not enough evidence to support its positive effect on reducing enamel demineralization and the pathogenic bacteria around brackets. In summary, flash-free might be a better choice for clinical bracket bonding.

Erratum: Low-intensity Pulsed Ultrasound regulates alveolar bone homeostasis in experimental Periodontitis by diminishing Oxidative Stress: Erratum.

[This corrects the article DOI: 10.7150/thno.42508.].

Biomechanical analysis of reinstating buccally flared maxillary 2nd molars using 3D printing anchorage supports: a 3D finite element study.

The buccally flared maxillary 2nd molar has certain consequences on oral function and health. However, existing methods have some degree of disadvantages, such as invasion, complexity and side effects. The objectives of this study were to design anchorage systems to correct buccally flared maxillary 2nd molars and analyze their biomechanical effects by 3-dimensional (3D) finite element analysis. Finite element (FE) models of the 3D tanspalatal arches (TPAs) and 3D splints with different thicknesses and force points were constructed. The stress distribution on teeth, the hydrostatic pressure on periodontal ligaments and the initial displacement of teeth were analyzed. A total of 18 FE models were constructed and analyzed. The stress concentrated on a single anchorage tooth, and the hydrostatic pressure and initial displacement of the anchorage tooth were greater than those of the malposed 2nd molar in the 3D splint anchorage system. The stress spread on all anchorage teeth and the hydrostatic pressure and initial displacement of the anchorage tooth were less than those of the malposed 2nd molar in the 3D TPA anchorage system. Theoretically, the 3D TPA was better than the 3D splint as an anchorage to correct the buccally flared 2nd molar. A combination of 0.8 mm of thickness and mesial force point provided the optimal conditions for the 3D TPA. Further clinical studies should be conducted to verify the effects of 3D appliances.

Metformin inhibits proliferation of oral squamous cell carcinoma cells by suppressing proteolysis of nerve growth factor receptor.

OBJECTIVE: We aimed to explore the effects of metformin on oral squamous cell carcinoma (OSCC) cell proliferation and the associated molecular mechanisms. METHODS: We established an OSCC model in SCC15 cells overexpressing nerve growth factor receptor (NGFR) or the N-terminal region (aa 1-250; NGFR-N), and assessed cell proliferation by CCK-8 assay, colony formation assay, and cell cycle analysis. Levels of NGFR and related genes and proteins were detected by qPCR and western blotting, and NGFR and NGFR-N affinity for p53 was assessed by immunoprecipitation assay. Additionally, the effects of NGFR and NGFR-N on p53 binding with its downstream gene promoters were analyzed by chromatin immunoprecipitation. RESULTS: Metformin inhibited OSCC cell proliferation and blocked NGFR proteolysis, thereby reducing the generation of its intracellular domain and NGFR-N. Moreover, compared with NGFR, NGFR-N showed higher affinity for p53 and more strongly inactivated p53 to promote cell proliferation. Furthermore, upregulation of NGFR-N downregulated levels of p53-specific downstream transcripts and proteins, whereas these levels were significantly upregulated in metformin-treated cells overexpressing NGFR. CONCLUSIONS: These results showed that metformin inhibited cell proliferation by suppressing NGFR proteolysis, thereby promoting its antitumor effect in OSCC and offering novel insight into a role for metformin in OSCC treatment.

Low-intensity Pulsed Ultrasound regulates alveolar bone homeostasis in experimental Periodontitis by diminishing Oxidative Stress.

Periodontitis is a widespread oral disease that results in the loss of alveolar bone. Low-intensity pulsed ultrasound (LIPUS), which is a new therapeutic option, promotes alveolar bone regeneration in periodontal bone injury models. This study investigated the protective effect of LIPUS on oxidative stress in periodontitis and the mechanism underlying this process. Methods: An experimental periodontitis model was induced by administering a ligature. Immunohistochemistry was performed to detect the expression levels of oxidative stress, osteogenic, and osteoclastogenic markers in vivo. Cell viability and osteogenic differentiation were analyzed using the Cell Counting Kit-8, alkaline phosphatase, and Alizarin Red staining assays. A reactive oxygen species assay kit, lipid peroxidation MDA assay kit, and western blotting were used to determine oxidative stress status in vitro. To verify the role of nuclear factor erythroid 2-related factor 2 (Nrf2), an oxidative regulator, during LIPUS treatment, the siRNA technique and Nrf2-/- mice were used. The PI3K/Akt inhibitor LY294002 was utilized to identify the effects of the PI3K-Akt/Nrf2 signaling pathway. Results: Alveolar bone resorption, which was experimentally induced by periodontitis in vivo, was alleviated by LIPUS via activation of Nrf2. Oxidative stress, induced via H2O2 treatment in vitro, inhibited cell viability and suppressed osteogenic differentiation. These effects were also alleviated by LIPUS treatment via Nrf2 activation. Nrf2 silencing blocked the antioxidant effect of LIPUS by diminishing heme oxygenase-1 expression. Nrf2-/- mice were susceptible to ligature-induced periodontitis, and the protective effect of LIPUS on alveolar bone dysfunction was weaker in these mice. Activation of Nrf2 by LIPUS was accompanied by activation of the PI3K/Akt pathway. The oxidative defense function of LIPUS was inhibited by exposure to LY294002 in vitro. Conclusions: These results demonstrated that LIPUS regulates alveolar bone homeostasis in periodontitis by attenuating oxidative stress via the regulation of PI3K-Akt/Nrf2 signaling. Thus, Nrf2 plays a pivotal role in the protective effect exerted by LIPUS against ligature-induced experimental periodontitis.

Short implants versus longer implants in the posterior alveolar region after an observation period of at least five years: A systematic review and meta-analysis.

OBJECTIVES: This meta-analysis compared clinical outcomes, including survival rate, marginal bone loss (MBL), and technical and biological complications of short implants (<7 mm) and long implants (≥7 mm) placed in the posterior alveolar bone. SOURCES: Electronic (via PubMed, EMBASE, Cochrane Library) and manual searches were performed for articles published prior to November 29, 2019. STUDY SELECTION: The review protocol was registered with PROSPERO (CRD42019140718). Only randomized controlled trials (RCTs) comparing short implants and standard implants in the same study after an observation period of at least five years were included. DATA: Nine RCTs were included in this study. The survival rates of short implants (<7 mm) ranged from 86.7 %-98.5 %, whereas the survival rates of longer implants (≥7 mm) were 95.1%-100% with follow-up ranging from 5 to 10 years. Dichotomous variables were compared using the Mantel-Haenszel (MH) method, and continuous variables were compared using the inverse variance (IV) method. The random effects model and the fixed effects model were used. Meta-analyses showed that short implants had a poorer survival rate than longer implants (P = 0.008). Short implants were associated with lower MBL than longer implants (P < 0.001). The biological complications of short implants were lower (P < 0.001) and the technical complications were higher, than those of long implants (P = 0.006). CONCLUSIONS: The results indicate that although the survival rate of short implants in the maxilla may be lower than that of long implants, the survival rate of short implants in the mandible is similar to that of long implants, and short implants can result in a lower rate of biological complications. The conclusions should be interpreted with caution due to the limited numbers of participants and implants. CLINICAL SIGNIFICANCE: When selecting the length of implants, surgeons should consider survival rate, the location of implant placement, their own clinical experience, and the incidence of complications.

Low-intensity pulsed ultrasound upregulates osteogenesis under inflammatory conditions in periodontal ligament stem cells through unfolded protein response.

BACKGROUND: In periodontal tissue engineering, periodontal ligament stem cells derived from patients with periodontitis (P-PDLSCs) are among the most promising and accessible stem cells for repairing disrupted alveolar bone and other connective tissues around the teeth. However, the inflammatory environment influences the osteogenic differentiation ability of P-PDLSCs. We examined low-intensity pulsed ultrasound (LIPUS) in P-PDLSCs in vitro and in rats with experimental periodontitis to determine whether LIPUS can enhance the osteogenic differentiation of stem cells. MATERIALS AND METHODS: P-PDLSCs were harvested and isolated from the periodontal tissues around the teeth of periodontitis patients, and healthy PDLSCs (H-PDLSCs) were obtained from tissues around healthy teeth. After validation by flow cytometry analysis, the P-PDLSCs were cultured in osteogenic medium either pretreated with the endoplasmic reticulum stress (ERS) inhibitor 4-phenyl butyric acid (4-PBA) or not pretreated and then treated with or without LIPUS (90 mW/cm2, 1.5 MHz) for 30 min per day. Cell viability, ERS marker expression, and osteogenic potential were determined between the different treatment groups. LPS-induced H-PDLSCs were used to mimic the inflammatory environment. In addition, we established a model of experimental periodontitis in rats and used LIPUS and 4-PBA as treatment methods. Then, the maxillary bone was collected, and micro-CT and histology staining methods were used to detect the absorption of alveolar bone. RESULTS: Our data showed that the P-PDLSCs derived from periodontitis tissues were in a more pronounced ERS state than were the H-PDLSCs, which resulted in the former being associated with increased inflammation and decreased osteogenic ability. LIPUS can alleviate ERS and inflammation while increasing the bone formation capacity of P-PDLSCs in vivo and in vitro. CONCLUSIONS: LIPUS may be an effective method to enhance the outcome of periodontal tissue engineering treatments of periodontitis by suppressing inflammation and increasing the osteogenic differentiation of P-PDLSCs through the unfolded protein response pathway, and more detailed studies are needed in the future.

Metformin prevents against oxidative stress-induced senescence in human periodontal ligament cells.

Periodontitis is a chronic infectious disease involving periodontal tissues. Periodontal ligament cells (PDLCs) play an important role in the regeneration of periodontal tissue. However, senescent PDLCs have an impeded regenerative potential. Metformin has been reported to prevent senescence at both the cellular and individual levels. The objectives of the present study were to evaluate the effects of metformin on cellular senescence in human PDLCs (hPDLCs) under oxidative stress. hPDLCs were pretreated with metformin, followed by H2O2 exposure. The cell viability, oxidative damage, cellular senescence and osteogenic potential were detected. To inhibit autophagy, hPDLCs were treated with 3-methyladenine before metformin treatment. The present study revealed that H2O2 exposure inhibits proliferation, increased lysosomal ß-galactosidase activity, augments reactive oxidative species (ROS) accumulation, elevates the oxidative damage, stimulates the expression of senescence-related genes and impedes the activity of the osteogenic differentiation of hPDLCs. Metformin pretreatment could partly reverse the detrimental influences of H2O2 on hPDLCs. Moreover, metformin could stimulate autophagy, whereas the inhibition of autophagy with 3-methyladenine reversed the anti-senescence effects of metformin on hPDLCs under oxidative stress. The present study manifested that metformin could alleviate oxidative stress-induced senescence via stimulating autophagy and could partially recover the osteogenic potential of hPDLCs, possibly providing a reference for the discovery of periodontal treatment from the perspective of antisenescence.

Metformin inhibits cell proliferation in SKM-1 cells via AMPK-mediated cell cycle arrest.

Metformin, a widely used antidiabetic drug, has previously been demonstrated to exert anti-cancer effects in certain hematological malignancies, but its effects on the transformation of myelodysplastic syndromes to acute myeloid leukemia (AML-MDS) remain unclear. The present study aimed to investigate the effects of metformin on SKM-1 cells (an AML-MDS cell line) and its underlying mechanisms. SKM-1 cells were treated with different concentrations of metformin. Cell proliferation was assayed by CCK-8. Apoptosis and cell cycle phases were detected by flow cytometry, while cell cycle related proteins and AMPK were tested by Western blot. SKM-1 cells were transfected with LV-AMPKα1-RNAi to reduce the expression of AMPK. Metformin inhibited cell proliferation in a dose and time dependent manner by inducing G0/G1 phase arrest rather than apoptosis induction. Metformin promoted the expression of p-AMPK, P53, P21CIP1 and P27KIP1, while inhibited the expression of CDK4 and CyclinD1. AMPK knockdown attenuated the effects of metformin on SKM-1 cells. These findings suggested that metformin inhibited proliferation of SKM-1 cells, potentially through an AMPK-mediated cell cycle arrest.

Low-intensity pulsed ultrasound promotes tissue regeneration in rat dental follicle cells in a porous ceramic scaffold.

The aim of this study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) on the osteogenic differentiation of dental follicle cells (DFCs) in vitro and on the regenerative effects of DFC-OsteoBoneTM complexes in vivo. DFCs were isolated and characterized. In the in vitro study, DFCs were cultured in an osteogenic medium in the presence or absence of LIPUS. The expression levels of ALP, Runx2, OSX, and COL-I mRNA were analyzed using real-time polymerase chain reaction (RT-PCR) on day 7. Alizarin red staining was performed on day 21. The state of the growth of the DFCs that were seeded on the scaffold at 3, 5, 7, and 9 days was detected by using a scanning electron microscope. In our in vivo study, 9 healthy nude mice randomly underwent subcutaneous transplantation surgery in one of three groups: group A, empty scaffold; group B, DFCs + scaffold; and group C, DFCs + scaffold + LIPUS. After 8 weeks of implantation, a histological analysis was performed by HE and Mason staining. Our results indicate that LIPUS promotes the osteogenic differentiation of DFCs by increasing the expression of the ALP, Runx2, OSX, and COL-I genes and the formation of mineralized nodules. The cells can adhere and grow on the scaffolds and grow best at 9 days. The HE and Mason staining results showed that more cells, fibrous tissue and blood vessels could be observed in the DFCs + scaffold + LIPUS group than in the other groups. LIPUS could promote the osteogenic differentiation of DFCs in vitro and promote tissue regeneration in a DFCs-scaffold complex in vivo. Further studies should be conducted to explore the underlying mechanisms of LIPUS.

Proteomics and N-glycoproteomics analysis of an extracellular matrix-based scaffold-human treated dentin matrix.

Extracellular matrix (ECM)-based biomaterials developed from mammalian tissues have been successfully used in preclinical and clinical tissue engineering applications. We have previously reported about the applicability of dentin-based scaffold, treated dentin matrix (TDM), for tooth root regeneration. However, TDM protein composition has not been characterized. Here, we used a shotgun proteomic strategy to profile human TDM proteome. N-glycoproteins were enriched by lectin affinity chromatography and identified by mass spectrometry. The total human TDM proteome was compared with the previously published human dentin proteome, and bioinformatics analysis were performed accordingly. In total, 708 proteins were identified by mass spectrometry in human TDM, of which 208 were N-glycoproteins with 318 identified glycosylation sites. Collagens, proteoglycans, small integrin-binding ligand N-linked glycoproteins (SIBLINGs), and growth factors, such as COL1A1, biglycan, dentin sialoprotein, and transforming growth factor beta 1, were identified. Glycoproteins were enriched in "biological processes" Gene Ontology terms such as cellular process, biological regulation, response to stimulus, metabolic process, immune system process, and biological adhesion. Thus, our comprehensive study of the human TDM proteome revealed that dentin proteins are more heterogeneous than previously documented. Our findings provide clues for designing new biomaterials for tooth root regeneration and understanding dentin formation.

Effect of metformin on human periodontal ligament stem cells cultured with polydopamine-templated hydroxyapatite.

Polydopamine-templated hydroxyapatite (tHA) is a type of nano-biomaterial that can promote osteogenesis in bone tissue engineering. However, high concentrations of tHA stimulate production of reactive oxygen species (ROS), resulting in cell injury and apoptosis. Metformin has been demonstrated to activate the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway, which induces autophagy and decreases ROS production to prevent apoptosis. The present study was performed to investigate the potential application of tHA in combination with metformin in periodontal bone tissue engineering. Human periodontal ligament stem cells (hPDLSCs) were exposed to tHA in the presence or absence of metformin, and cytocompatibility and osteogenesis were detected by related assays. Additionally, the autophagy signaling pathway was analyzed by western blotting. Polydopamine-templated hydroxyapatite, in combination with metformin, substantially reduced ROS production and apoptosis, and enhanced proliferation and osteogenic differentiation of hPDLSCs. Enhanced levels of microtubule-associated protein 1 light chain 3 II and Beclin-1 were observed after exposure to tHA plus metformin. Expression of phosphorylated AMPK was increased and that of phosphorylated mammalian target of rapamycin (mTOR) was decreased after exposure to tHA plus metformin. Taken together, our results demonstrate that tHA, combined with metformin, increases the viability of hPDLSCs via the AMPK/mTOR signaling pathway by regulating autophagy and further improving the osteogenic effect.

Low-intensity pulsed ultrasound promotes tissue regeneration in rat dental follicle cells in a porous ceramic scaffold

Abstract The aim of this study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) on the osteogenic differentiation of dental follicle cells (DFCs) in vitro and on the regenerative effects of DFC-OsteoBoneTM complexes in vivo. DFCs were isolated and characterized. In the in vitro study, DFCs were cultured in an osteogenic medium in the presence or absence of LIPUS. The expression levels of ALP, Runx2, OSX, and COL-I mRNA were analyzed using real-time polymerase chain reaction (RT-PCR) on day 7. Alizarin red staining was performed on day 21. The state of the growth of the DFCs that were seeded on the scaffold at 3, 5, 7, and 9 days was detected by using a scanning electron microscope. In our in vivo study, 9 healthy nude mice randomly underwent subcutaneous transplantation surgery in one of three groups: group A, empty scaffold; group B, DFCs + scaffold; and group C, DFCs + scaffold + LIPUS. After 8 weeks of implantation, a histological analysis was performed by HE and Mason staining. Our results indicate that LIPUS promotes the osteogenic differentiation of DFCs by increasing the expression of the ALP, Runx2, OSX, and COL-I genes and the formation of mineralized nodules. The cells can adhere and grow on the scaffolds and grow best at 9 days. The HE and Mason staining results showed that more cells, fibrous tissue and blood vessels could be observed in the DFCs + scaffold + LIPUS group than in the other groups. LIPUS could promote the osteogenic differentiation of DFCs in vitro and promote tissue regeneration in a DFCs-scaffold complex in vivo. Further studies should be conducted to explore the underlying mechanisms of LIPUS.

Effects of Papacarie on children with dental caries in primary teeth: a systematic review and meta-analysis.

BACKGROUND: Caries in primary teeth hinder the child to bite and chew and influence their development. Papacarie has the characteristics of selective removal of decayed tissue and can preserve healthy dentine to the maximum, but its efficiency has not been critically evaluated compared to conventional method. AIM: This review is aiming at comparing the Papacarie and traditional method in caries removal in primary dental caries with children. DESIGN: Comprehensive literature searching at PubMed, Embase, Cochrane Central Register of Controlled Trials, and Web of Science to January 2018. RESULTS: Six randomized controlled trials (RCTs) and four prospective controlled clinical trials (CCTs) were included. The microbiota in caries dentine was significantly reduced using the Papacarie treatment (MD = 0.57, 95% CI 0.04 to 1.09, P = 0.03), and the anxiety feeling declined more in the Papacarie group (MD = -1.01, 95% CI -1.72 to -0.30, P < 0.005). There was a greater 200.79 (MD = 200.79, 95%CI 152.50 to 249.09, P < 0.00001) increase in time taken for the Papacarie treatment compared with the conventional method. CONCLUSION: Papacarie exerts a positive effect in reducing the bacteria and decreases the pain during caries removal in primary teeth although it costed a longer treatment time compared with the conventional method.

Effects of periodontal endoscopy on the treatment of periodontitis: A systematic review and meta-analysis.

BACKGROUND: For this systematic review, the authors evaluated and synthesized the available scientific evidence related to the effects of periodontal endoscopy on the treatment of periodontitis. METHODS: The authors searched PubMed, Embase, Cochrane Library, Chinese Scientific Journals database, China National Knowledge Infrastructure, and Chinese Medicine Premier's Wanfang database for articles about periodontal endoscopy that were published through January 2017. The authors considered the percentage of residual calculus, average treatment time, bleeding on probing (BOP), gingival inflammation (GI), and probing depth (PD) as outcome measures. The authors extracted data and performed meta-analyses for groups of articles for which it was appropriate. RESULTS: The authors identified 8 articles as being suitable for this systematic review. The investigators of 3 studies reported results related to BOP and GI that revealed some advantages of periodontal endoscopy over traditional scaling and root planing (SRP). The investigators of 4 studies explored PD and found no difference between periodontal endoscopy and traditional SRP. The authors could not perform meta-analyses on the study results related to BOP, GI, or PD. The percentage of residual calculus after periodontal endoscope-aided debridement was significantly less than the percentage of residual calculus after traditional SRP (mean difference, -3.18; 95% confidence interval, -4.86 to -1.49; P = .002; heterogeneity I2 = 74%). The authors found that periodontal endoscopy took significantly more time than traditional SRP (mean difference, 6.01 minutes; 95% confidence interval, 4.23 to 7.8; P < .00001; heterogeneity I2 = 0%). CONCLUSIONS AND PRACTICAL IMPLICATIONS: Periodontal endoscopy may provide additional benefits for calculus removal compared with traditional SRP, although it could take more time to perform. With respect to BOP, GI, and PD, the authors found no sufficient evidence to support the difference between the use of periodontal endoscopy and traditional SRP. The authors concluded that additional scientific research is required to assess the effects of periodontal endoscopy on the treatment of periodontitis.