Type 1 diabetes, glycemic traits, and risk of dental caries: a Mendelian randomization study

Background: Regarding past epidemiological studies, there has been disagreement over whether type 1 diabetes (T1DM) is one of the risk factors for dental caries. The purpose of this study was to determine the causative links between genetic susceptibility to T1DM, glycemic traits, and the risk of dental caries using Mendelian randomization (MR) approaches. Methods: Summary-level data were collected on genome-wide association studies (GWAS) of T1DM, fasting glucose (FG), glycated hemoglobin (HbA1c), fasting insulin (FI), and dental caries. MR was performed using the inverse-variance weighting (IVW) method, and sensitivity analyses were conducted using the MR-Egger method, weighted median, weighted mode, replication cohort, and multivariable MR conditioning on potential mediators. Results: The risk of dental caries increased as a result of genetic susceptibility to T1DM [odds ratio (OR) = 1.044; 95% confidence interval (CI) = 1.015-1.074; p = 0.003], with consistent findings in the replication cohort. The relationship between T1DM and dental caries was stable when adjusted for BMI, smoking, alcohol intake, and type 2 diabetes (T2DM) in multivariable MR. However, no significant correlations between the risk of dental caries and FG, HbA1c, or FI were found. Conclusion: These results indicate that T1DM has causal involvement in the genesis of dental caries. Therefore, periodic reinforcement of oral hygiene instructions must be added to the management and early multidisciplinary intervention of T1DM patients, especially among adolescents and teenagers, who are more susceptible to T1DM.

Kangfuxin Accelerates Extraction Socket Healing by Promoting Angiogenesis Via Upregulation of CCL2 in Stem Cells

Kangfuxin (KFX) shows potential in wound healing, but its role in socket healing is unclear. This research finds increased bone mass, mineralization, and collagen deposition in KFX-treated mice. Mouse bone marrow mesenchymal stem cells, human periodontal ligament stem cells (hPDLSCs), and human dental pulp stem cells (hDPSCs) are treated with KFX under osteogenic induction. RNA-sequencing reveals upregulated chemokine-related genes, with a threefold increase in chemokine (C-C motif) ligand 2 (Ccl2). The conditioned medium (CM) of hPDLSCs and hDPSCs treated with KFX promotes endothelial cell migration and angiogenesis. Ccl2 knockdown abolishes CM-induced endothelial cell migration and angiogenesis, which can be reversed by recombinant CCL2 treatment. KFX-treated mice showed increased vasculature. In conclusion, KFX increases the expression of CCL2 in stem cells, promoting bone formation and mineralization in the extraction socket by inducing endothelial cell angiogenesis. © 2023 American Society for Bone and Mineral Research (ASBMR).

Chitosan nanoparticles for sustained release of metformin and its derived synthetic biopolymer for bone regeneration

Background: There are considerable socioeconomic costs associated with bone defects, making regenerative medicine an increasingly attractive option for treating them. Chitosan is a natural biopolymer; it is used in approaches for sustained slow release and osteogenesis, and metformin has osteoinductivity. Our study aimed to synthesize chitosan and human serum albumin (HSA) with a metformin nanoformulation to evaluate the therapeutic effects of this nanoformulation on bone defects in vitro. Methods: A pluripotent differentiation assay was performed in vitro on mouse bone marrow mesenchymal stem cells (BMSCs). Cell Counting Kit-8 was used to detect whether metformin was toxic to BMSCs. The osteogenesis-related gene expression of osteocalcin (OCN) and osteoprotegerin (OPG) from BMSCs was tested by real-time polymerase chain reaction (PCR). HSA, metformin hydrochloride, and chitosan mixtures were magnetically stirred to finish the assembly of metformin/HSA/chitosan nanoparticles (MHC NPs). The MHC NPs were characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FT-IR). To test the expression of OCN and OPG, western blot were used. MHC NPs were evaluated in vitro for their osteoinductivity using alkaline phosphatase (ALP). Results: BMSCs successfully differentiated into osteogenic and adipogenic lineages in vitro. According to real-time PCR, a 50 µM concentration of metformin promoted osteogenesis in BMSCs most effectively by upregulating the osteogenic markers OCN and OPG. The microstructure of MHC NPs was spherical with an average nanosize of 20 ± 4.7 nm and zeta potential of -8.3 mV. A blueshift and redshift were observed in MHC NPs following exposure to wavelengths of 1,600-1,900 and 2,000-3,700 nm, respectively. The encapsulation (%) of metformin was more than 90%. The simulation study showed that MHC NPs have good stability and it could release metformin slowly in vitro at room temperature. Upon treatment with the studied MHC NPs for 3 days, ALP was significantly elevated in BMSCs. In addition, the MHC NPs-treated BMSCs upregulated the expression of OPG and OCN, as shown by real-time PCR and western blot. Conclusion: MHC NPs have a stable metformin release effect and osteogenic ability. Therefore, as a derived synthetic biopolymer, it is expected to play a role in bone tissue regeneration.

Potential interaction between the oral microbiota and COVID-19: a meta-analysis and bioinformatics prediction

Objectives

The purpose of this study was to evaluate available evidence on the association between the human oral microbiota and coronavirus disease 2019 (COVID-19) and summarize relevant data obtained during the pandemic.

Methods

We searched EMBASE, PubMed, and the Cochrane Library for human studies published up to October 2022. The main outcomes of the study were the differences in the diversity (α and β) and composition of the oral microbiota at the phylum and genus levels between patients with laboratory-confirmed SARS-CoV-2 infection (CPs) and healthy controls (HCs). We used the Human Protein Atlas (HPA), Gene Expression Profiling Interactive Analysis (GEPIA) database, Protein-protein interaction (PPI) network (STRING) and Gene enrichment analysis (Metascape) to evaluate the expression of dipeptidyl peptidase 4 (DPP4) (which is the cell receptor of SARS CoV-2) in oral tissues and evaluate its correlation with viral genes or changes in the oral microbiota.

Results

Out of 706 studies, a meta-analysis of 9 studies revealed a significantly lower alpha diversity (Shannon index) in CPs than in HCs (standardized mean difference (SMD): -0.53, 95% confidence intervals (95% CI): -0.97 to -0.09). Subgroup meta-analysis revealed a significantly lower alpha diversity (Shannon index) in older than younger individuals (SMD: -0.54, 95% CI: -0.86 to -0.23/SMD: -0.52, 95% CI: -1.18 to 0.14). At the genus level, the most significant changes were in Streptococcus and Neisseria, which had abundances that were significantly higher and lower in CPs than in HCs based on data obtained from six out of eleven and five out of eleven studies, respectively. DPP4 mRNA expression in the oral salivary gland was significantly lower in elderly individuals than in young individuals. Spearman correlation analysis showed that DPP4 expression was negatively correlated with the expression of viral genes. Gene enrichment analysis showed that DPP4-associated proteins were mainly enriched in biological processes, such as regulation of receptor-mediated endocytosis of viruses by host cells and bacterial invasion of epithelial cells.

Conclusion

The oral microbial composition in COVID-19 patients was significantly different from that in healthy individuals, especially among elderly individuals. DPP4 may be related to viral infection and dysbiosis of the oral microbiome in elderly individuals.

Oral cavity-derived stem cells and preclinical models of jaw-bone defects for bone tissue engineering

BACKGROUND

Jaw-bone defects caused by various diseases lead to aesthetic and functional complications, which can seriously affect the life quality of patients. Current treatments cannot fully meet the needs of reconstruction of jaw-bone defects. Thus, the research and application of bone tissue engineering are a "hot topic." As seed cells for engineering of jaw-bone tissue, oral cavity-derived stem cells have been explored and used widely. Models of jaw-bone defect are excellent tools for the study of bone defect repair in vivo. Different types of bone defect repair require different stem cells and bone defect models. This review aimed to better understand the research status of oral and maxillofacial bone regeneration.

MAIN TEXT

Data were gathered from PubMed searches and references from relevant studies using the search phrases "bone" AND ("PDLSC" OR "DPSC" OR "SCAP" OR "GMSC" OR "SHED" OR "DFSC" OR "ABMSC" OR "TGPC"); ("jaw" OR "alveolar") AND "bone defect." We screened studies that focus on "bone formation of oral cavity-derived stem cells" and "jaw bone defect models," and reviewed the advantages and disadvantages of oral cavity-derived stem cells and preclinical model of jaw-bone defect models.

CONCLUSION

The type of cell and animal model should be selected according to the specific research purpose and disease type. This review can provide a foundation for the selection of oral cavity-derived stem cells and defect models in tissue engineering of the jaw bone.

Prevotella genus and its related NOD-like receptor signaling pathway in young males with stage III periodontitis

Background

As periodontitis progresses, the oral microbiota community changes dynamically. In this study, we evaluated the dominant bacteria and their roles in the potential pathway in young males with stage III periodontitis.

Methods

16S rRNA sequencing was performed to evaluate variations in the composition of oral bacteria between males with stage I and III periodontitis and identify the dominant bacteria of each group. Function prediction was obtained based on 16S rRNA sequencing data. The inhibitor of the predominant pathway for stage III periodontitis was used to investigate the role of the dominant bacteria in periodontitis in vivo and in vitro.

Results

Chao1 index, Observed Species and Phylogenetic Diversity (PD) whole tree values were significantly higher in the stage III periodontitis group. β-diversity suggested that samples could be divided according to the stages of periodontitis. The dominant bacteria in stage III periodontitis were Prevotella, Prevotella_7, and Dialister, whereas that in stage I periodontitis was Cardiobacterium. KEGG analysis predicted that variations in the oral microbiome may be related to the NOD-like receptor signaling pathway. The inhibitor of this pathway, NOD-IN-1, decreased P. intermedia -induced Tnf-α mRNA expression and increased P. intermedia -induced Il-6 mRNA expression, consistent with the ELISA results. Immunohistochemistry confirmed the down-regulation of TNF-α and IL-6 expressions by NOD-IN-1 in P. intermedia-induced periodontitis.

Conclusion

The composition of the oral bacteria in young males varied according to the stage of periodontitis. The species richness of oral microtia was greater in young males with stage III periodontitis than those with stage I periodontitis. Prevotella was the dominant bacteria in young males with stage III periodontitis, and inhibition of the NOD-like receptor signaling pathway can decrease the periodontal inflammation induced by P. intermedia.

Comparison of sealer penetration of sonic activation versus conventional needle irrigation: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Most existing studies comparing the efficiency of sonic irrigation (SI) and conventional needle irrigation (CNI) in increasing the penetration of sealers into dentine tubules are controversial; and this study aimed to determine whether the use of SI can lead to greater sealing ability than CNI, during the root canal treatment.

METHODS

The EMBASE, PubMed, and Cochrane Library databases were used to find confocal laser scanning microscopy studies evaluating percentage and maximum depth of sealer penetration following the use of SI or CNI in mature permanent teeth until October 2022. The critical estimative checklist of randomized controlled trials of the standardized Joanna Briggs Institute was adopted to independently score the quality of each study. The random-effect model for meta-analysis was used to analyse for each canal segment (apical, middle, coronal). The results are shown in the forest plots as weighted mean differences (WMDs) with 95% confidence intervals (95% CIs).

RESULTS

Ninety-seven articles were included in the preliminary screening, and nine of them were included in this study. Eight studies were included in the meta-analysis.The meta-analysis exhibited great increases in the coronal (WMD: 8.09, 95% CI 2.78-13.40/WMD: 165.32, 95% CI 128.85-201.80), and middle segments (WMD: 8.81, 95% CI 5.76-11.87/WMD: 132.98, 95% CI 68.71-197.25) for the percentage and maximum depth of sealer penetration, respectively. The percentage of sealer penetration in the apical thirds region was nonsignificant (WMD: 4.73, 95% CI - 2.34-11.80). However, the maximum depth of sealer penetration in the apical thirds region was significant (WMD: 121.46, 95% CI 86.55-156.38). Chi-squared analysis revealed heterogeneity scores of 0.0-70.0% and 44.0-90.0% for the percentage and maximum depth of sealer penetration, respectively.

DISCUSSION

This review verified that SI significantly improves tubular dentin sealer penetration in most areas of the root canal; thus, SI may lead to better filling efficiency and anti-reinfection effects than CNI during and after the root canal therapy. Nevertheless, a large heterogeneity in the current data comparing the irrigation efficiency of SI versus CNI in the apical third of the root canal was found, implying the necessity to standardize root canal irrigation procedures and obtain more accurate results in this area.

TRIAL REGISTRATION

INPLASY database (INPLASY202270116).

The oral microbiome in young women at different stages of periodontitis: Prevotella dominant in stage III periodontitis

Objective

Periodontitis progression is related to the dynamic dysbiosis of oral microbiome. We identified the dominant bacteria and the potential pathway in young women with stage-III periodontitis.

Materials and methods

Samples of subgingival plaque were collected from 26 young women with periodontitis (20 with stage-I and 6 with stage-III). Using 16S rRNA-sequencing, we determined the variation in oral bacterial communities of the two groups, and identified the dominant bacteria of each group. We used the Kyoto Encyclopedia of Genes and Genomes (KEGG) database to evaluate the signaling pathways related to the difference in oral bacterial composition. The role of the dominant bacteria of stage-III periodontitis was investigated in vivo and in vitro using an endoplasmic reticulum stress inhibitor.

Results

Young women with stage-I periodontitis had higher values for the Chao1 Index, Observed Species and Phylogenetic Diversity Whole Tree Index than those for women with stage-III periodontitis. β-diversity analyses revealed that samples could be divided into different groups according to the periodontitis stage. The most representative biomarkers of stage-III periodontitis in young women were bacteria of the phylum Bacteroidetes, its order, family and genera Bacteroidales, Prevotellaceae and Prevotella. The KEGG database revealed that the change in oral bacterial composition of young women with stage-III periodontitis may be related to protein processing in an endoplasmic reticulum pathway. Salubrinal (an endoplasmic reticulum stress regulator) controlled expression of Runx2, Col1a1, Ocn in mouse bone-marrow mesenchymal cells. Salubrinal administration showed that moderate endoplasmic reticulum stress inhibited alveolar bone loss in periodontitis induced by Prevotella intermedia lipopolysaccharide.

Conclusion

Differences between periodontitis stages were noted and bacteria of Prevotella species were abundant in young women with stage-III periodontitis. This phenomenon was related to protein processing in an endoplasmic reticulum pathway.

Traditional Chinese medicine promotes bone regeneration in bone tissue engineering

Bone tissue engineering (BTE) is a promising method for the repair of difficult-to-heal bone tissue damage by providing three-dimensional structures for cell attachment, proliferation, and differentiation. Traditional Chinese medicine (TCM) has been introduced as an effective global medical program by the World Health Organization, comprising intricate components, and promoting bone regeneration by regulating multiple mechanisms and targets. This study outlines the potential therapeutic capabilities of TCM combined with BTE in bone regeneration. The effective active components promoting bone regeneration can be generally divided into flavonoids, alkaloids, glycosides, terpenoids, and polyphenols, among others. The chemical structures of the monomers, their sources, efficacy, and mechanisms are described. We summarize the use of compounds and medicinal parts of TCM to stimulate bone regeneration. Finally, the limitations and prospects of applying TCM in BTE are introduced, providing a direction for further development of novel and potential TCM.

Role of NOD2 and hepcidin in inflammatory periapical periodontitis

The immunological response occurring during periapical inflammation includes expression of nucleotide binding oligomerization domain containing 2 and hepcidin. Nucleotide binding oligomerization domain containing 2 deficiency increases infiltration of inflammatory cells close to alveolar bone. Hepcidin has an important role in iron metabolism affecting bone metabolism.We investigated the role of nucleotide binding oligomerization domain containing 2 and hepcidin in inflammatory periapical periodontitis. Periapical periodontitis was induced in rats and confirmed by micro-computed tomography. Nucleotide binding oligomerization domain 2 and hepcidin were evaluated through immunohistochemistry. Bioinformatics analysis was undertaken usingthe Kyoto Encyclopedia of Genes and Genomes and Gene Ontology databases. Micro-computer tomography revealed alveolar bone resorption in the periapical region and furcation area of mandibular molars in rats of the periapical periodontitis group. Immunohistochemistry showed increased expressionof nucleotide binding oligomerization domain containing 2 and hepcidin around root apices in rats of the periapical periodontitis group. Bioinformatics analysis of differentially expressed genes in inflamed and non-inflamed tissues revealed enrichment in the NOD-like receptor signaling pathway. Our data suggest that nucleotide binding oligomization domain contain2 and hepcidin have important roles in periapical periodontitis severity because they can reduce alveolar bone loss.They could elicit new perspectives for development of novel strategies for periapical periodontitis treatment.

Gender Variations in the Oral Microbiomes of Elderly Patients with Initial Periodontitis

Periodontitis is a globally prevalent disease that imposes a functional and aesthetic burden on patients. The oral microbiome influences human health. The aim of this study was at assessing gender variation in the subgingival bacterial microbiome of elderly patients with initial periodontitis and to determine the causes of this variation. Twelve males and twenty females (range 50-68 years old) with initial periodontitis provided subgingival plaque samples. 16S rRNA gene sequencing, QIIME-based data processing, and statistical analyses were carried out using several different analytical approaches to detect differences in the oral microbiome between the two groups. Males had higher Chao1 index, observed species, and phylogenetic diversity whole tree values than females. Analysis of β-diversity indicated that the samples were reasonably divided by the gender. The linear discriminant analysis effect size showed that the most representative biomarkers were the genus Haemophilus in males, whereas the dominant bacteria in females were Campylobacter. Kyoto Encyclopedia of Genes and Genomes analysis showed that predicting changes in the female oral microbiota may be related to the immune system and immune system diseases are the main factor in males. These data suggest that gender may be a differentiating factor in the microbial composition of subgingival plaques in elderly patients with initial periodontitis. These results could deepen our understanding of the role of gender in the oral microbiota present during initial periodontitis.