Site selection of micro-implant anchorages in the infrazygomatic crest in adult orthodontic patients.

OBJECTIVES: To determine the optimal placement of miniscrews, this study compared adult male and female patients in terms of cortical bone density, cortical bone thickness, and available bone width in the infrazygomatic crest region. METHODS: The cone beam computed tomography imaging data of 200 patients (20-30 years old; 100 males and 100 females) were collected. The right maxillary posterior teeth in the sagittal plane were divided into six levels from proximal to distal, and three measurement sites were positioned at vertical distances of 8, 10, and 12 mm from the cementum. Cortical bone density, cortical bone thickness, and available bone width were measured in 18 measurement sites in the infrazygomatic crest and analyzed statistically. RESULTS: The highest cortical bone density, cortical bone thickness, and available bone width in the infrazygomatic crest in adult male and female patients were at the level of the interradicular space between the maxillary second premolar and maxillary first molar. The bone cortical density and thickness increased with vertical height, whereas the available bone width decreased with increasing vertical height. Differences were observed in cortical bone density, cortical bone thickness, and available bone width between adult male and female patients. CONCLUSIONS: The optimal implantation sites of the micro-implant anchorages in the infrazygomatic crest were at the level of the interradicular space between the maxillary second premolar and the maxillary first molar, and the vertical height of the optimal implantation site in males was appropriately higher than that in females.

Meta-analysis of condylar changes produced by a Twin-block appliance in Class â ¡ malocclusion.

OBJECTIVES: To evaluate the effects of a Twin-block appliance on the condyles of patients with ClassⅡmalocclusion by conducting a systematic review and a Meta-analysis. METHODS: Pubmed, Embase, Cochrane Library, Chinese BioMedical Literature Database, China National Knowledge Infrastructure, and VIP Database were electronically searched. Randomized controlled trials, controlled clinical trials, and single-arm trials on condylar changes produced by a Twin-block appliance in patients with ClassⅡmalocclusion were included. Two reviewers independently extracted and assessed the risk of bias. Meta-analyses were conducted with Review Manager 5.3. RESULTS: Eight studies were included; among which, seven were of high quality. After treatment with a twin block appliance, condyles moved anteriorly. The anterior joint spaces decreased (P<0.000 01), whereas the posterior spaces increased (P<0.000 01). The superior spaces were not changed (P=0.11). Moreover, a significant difference was observed in the increase of the condylar space index (P<0.000 01). After treatment, the anteroposterior diameters of the condyles and condylar height increased (P=0.000 2 and P<0.000 01, respectively). By contrast, no significant changes were discovered in the medial external diameters of the condyles (P=0.42). CONCLUSIONS: A Twin-block appliance can promote the growth of a condyle in the posterior and upper direction and move it forward in favor of the correction of Class Ⅱ malocclusion.

Periodontal Ligament Stem Cell-Derived Extracellular Vesicles Enhance Tension-Induced Osteogenesis.

Tension-induced osteogenesis has great significance in maintaining bone homeostasis and ensuring the efficiency and stability of orthodontic treatment. Recently, extracellular vesicles (EVs) have shown great potential in regulating bone remodeling. Here, we aimed to explore the effects of periodontal ligament stem cell (PDLSC)-derived EVs on tension-induced osteogenesis and the potential mechanism. PDLSC-derived EVs were extracted by ultracentrifugation. In vitro, PDLSC-derived EVs of 10 µg/mL significantly improved the proliferation of MC3T3-E1 cells and enhanced the osteogenic differentiation of osteoblasts under a tensile strain of 2000 uε. Next, a mouse model of orthodontic tooth movement (OTM) was established and treated with subperiosteal injection of PDLSC-derived EVs (1 mg/kg) on the tension side. The results showed that treatment with PDLSC-derived EVs effectively enhanced OTM and promoted osteogenesis on the tension side, including increasing trabecular bone parameters and promoting the expression of osteogenic-related biomarkers (OCN and OPN). More interestingly, we identified several mechano-sensitive miRNAs enriched in PDLSC-derived EVs by high-throughput miRNA sequencing. Bioinformatics analysis indicated that they were related to various osteogenesis-related signaling pathways. Therefore, PDLSC-derived EVs could improve the efficiency of OTM by enhancing tension-induced osteogenesis of osteoblasts. Our study may provide potential evidence for the promoting effects of PDLSC-derived EVs on osteogenesis and offer new insights into the development of treatment strategies for enhancing osteogenesis in orthodontic treatment and other metabolic bone diseases.

Wnt5a-Ror2 signaling mediates root resorption.

INTRODUCTION: This study aimed to investigate the role of wingless-type MMTV integration site family member 5a (Wnt5a)-receptor tyrosine kinase-like orphan receptor 2 (Ror2) signaling in root resorption. METHODS: The messenger RNA (mRNA) expression of Wnt5a, Ror2, and RANKL in periodontal ligament cells (PDLCs) under compression force (CF) with or without Ror2 small interfering RNA (siRNA) were measured by quantitative reverse transcription-polymerase chain reaction, and these proteins released into culture supernatants were measured using enzyme-linked immunosorbent assay. Then these PDLC-conditioned media under CF with or without Ror2 siRNA were used to culture osteoclast precursors to detect osteoclastogenesis effects via tartrate-resistant acid phosphatase staining. In in vivo studies, the odontoclast number and the root resorption volume under excessive CF with or without Ror2 siRNA were investigated by tartrate-resistant acid phosphatase immunohistochemical staining and microcomputed tomography. The protein levels for Wnt5a, Ror2, and receptor activator of nuclear factor-kappa B ligand (RANKL) in the periodontal ligament tissues were also detected using immunohistochemical staining. Finally, the odontoclast number, root resorption volume, and the mRNA and protein expressions were compared between immature and mature teeth. RESULTS: The mRNA production and protein release level of Wnt5a, Ror2, and RANKL increased after CF, whereas they were significantly downregulated with Ror2 siRNA. The osteoclast number increased treating with culture medium from PDLC applying CF, but the increase was inhibited after adding Ror2 siRNA. In the animal model, the odontoclast number and root resorption volume significantly increased in the CF group but decreased in the CF with the Ror2 siRNA group. The protein levels of Wnt5a, Ror2, and RANKL in periodontal ligament were upregulated under excessive CF, and the pathway was inhibited with Ror2 siRNA. In the immature tooth group, the odontoclast number, root resorption volume, and the mRNA and protein expressions of Wnt5a-Ror2 signaling were reduced. CONCLUSIONS: Wnt5a-Ror2 signaling in PDLCs enhanced by excessive CF could promote RANKL release and induce precursor differentiation, partly leading to increased odontoclast activity and ultimate root resorption. The less resorption of the immature tooth may be due to odontoclastogenesis inhibition by decreased expression of Wnt5a-Ror2 signaling.

Effects of artificial honey and epigallocatechin-3-gallate on streptococcus pyogenes.

BACKGROUND: Streptococcus pyogenes is an important global human pathogen that causes pharyngitis, and antibacterial therapy has become an important part of the overall therapy for pharyngitis. As natural derivatives, honey and green tea are often recommended for patients with pharyngitis in traditional Chinese medicine without experimental theoretical basis on wether the combined effect of honey and green tea on pharyngitis is better than they alone. The aims of this study were to explore the effects of artificial honey (AH) and epigallocatechin-3-gallate (EGCG) on S. pyogenes and elucidate the possible mechanisms, which were investigated using MIC (the minimum inhibitory concentration), FIC (fractional inhibitory concentration) index, growth pattern, biofilm formation and RT-qPCR. RESULTS: The MIC of AH on S. pyogenes was 12.5% (v/v) and the MIC of EGCG was 1250 µg/ml. The FIC index of AH and EGCG was 0.5. The planktonic cell growth, growth pattern and biofilm formation assays showed that AH and EGCG mixture had stronger inhibitory effect on S. pyogenes than they alone. RT-qPCR confirmed that the expression of hasA and luxS gene were inhibited by AH and EGCG mixture. CONCLUSIONS: AH and EGCG mixture can inhibit the planktonic cell growth, biofilm formation and some virulence genes expression of S. pyogenes, better than they alone. The combination of honey and green tea have the potential to treat pharyngitis as natural derivatives, avoiding drug resistance and double infection.

Inhibition of Streptococcus mutans Biofilm Formation by the Joint Action of Oxyresveratrol and Lactobacillus casei.

Microbial dysbiosis in dental plaque contributes to the occurrence of dental caries, to which Streptococcus mutans is a major contributor. Lactobacillus casei can be used as probiotic therapy to treat caries by replacing S. mutans within the dental plaque. However, the effects of probiotic treatment are not always stable. Oxyresveratrol (ORV), a plant-derived polyphenol, displays opposite effects in that it inhibits cariogenic and promotes commensal bacteria. Thus, the objectives of this study are to investigate the effects of ORV on bacterial proportions in S. mutans-L. casei biofilm and to elucidate how ORV weakens the competitiveness of S. mutans. Quantitative real-time PCR confirms a decreased S. mutans-L. casei ratio in dual-species biofilm by action of ORV. The culture supernatant of L. casei after being incubated with ORV (ORVLC) is prepared to explore the joint action of ORV and L. casei. ORVLC displays the strongest anti-biofilm effect against S. mutans when compared with the effects of L. casei supernatant or ORV alone. As a result of this treatment, both exopolysaccharides and bacteria contents in the biofilm are greatly reduced. The biofilm is transformed from water-insoluble glucan-dominant to water-soluble glucan-dominant by ORVLC through the modulation of the glycometabolism-related genes of S. mutans. As for the interactions between ORV and L. casei, ORV promotes L. casei to produce acetic acid, which provides L. casei with a competitive advantage against S. mutans. Taken together, ORV may be very suitable as an adjuvant medicine for probiotic therapy in the control of dental caries. IMPORTANCE The homeostatic imbalance in dental plaque associated with a sharp increase in the number of cariogenic bacteria such as Streptococcus mutans is critical for the occurrence and development of caries. Probiotic therapy can restore ecological balance by replacing cariogenic pathogens with probiotics. The current study innovatively finds that oxyresveratrol, a natural polyphenol, can provide probiotic Lactobacillus casei with competitive dominance in its dual-species biofilm with S. mutans. The joint action of oxyresveratrol and L. casei strongly inhibits the biofilm formation of S. mutans. Additionally, oxyresveratrol promotes L. casei to produce acetic acid, which facilitates L. casei to compete with S. mutans. Through the effects of these two mechanisms, oxyresveratrol leads to a significantly decreased S. mutans-L. casei ratio in their dual-species biofilm. Thus, oxyresveratrol is speculated to be an ideal medicine for the prevention and treatment of caries by regulating oral flora balance.

The Roles of Solute Carriers in Auditory Function.

Solute carriers (SLCs) are important transmembrane transporters with members organized into 65 families. They play crucial roles in transporting many important molecules, such as ions and some metabolites, across the membrane, maintaining cellular homeostasis. SLCs also play important roles in hearing. It has been found that mutations in some SLC members are associated with hearing loss. In this review, we summarize SLC family genes related with hearing dysfunction to reveal the vital roles of these transporters in auditory function. This summary could help us understand the auditory physiology and the mechanisms of hearing loss and further guide future studies of deafness gene identification.

Human Periodontal Ligament Stem Cell-Derived Exosomes Promote Bone Regeneration by Altering MicroRNA Profiles.

The role and underlying mechanism of exosomes derived from human periodontal ligament stem cells (PDLSC) in osteogenesis are unclear. In the present study, we identified the exosomes derived from PDLSCs and found that osteogenic induction can enhance the osteogenic ability of PDLSC-derived exosomes in promoting the osteogenic differentiation of rat bone marrow stem cells (BMSCs). To investigate the underlying mechanism, we analyzed the exosomal miRNA expression profiles of undifferentiated and osteogenic differentiated PDLSCs by RNA sequencing. The results showed that seventy-two miRNAs were upregulated and thirty-five miRNAs were downregulated after osteogenic induction. The results of Gene Ontology analysis and pathway analysis demonstrated that the target genes of differentially expressed exosomal miRNAs participate in the regulation of a variety of biological processes, such as catalytic activity, protein binding, metabolic processes, cell development, and differentiation, and are enriched in osteogenic differentiation-related pathways, such as MAPK signaling, AMPK signaling, and insulin signaling pathways. Our results reveal for the first time that the exosomal miRNAs derived from osteogenic differentiated PDLSCs may promote the osteogenic differentiation of BMSCs, which provides a basis for further research on the regulatory function of exosomal miRNA of PDLSCs during osteogenesis.

Oxyresveratrol promotes biofilm formation, cell attachment and aggregation of Streptococcus gordonii in the presence of sucrose.

Streptococcus gordonii is a commensal colonizer of oral cavity that initiates the formation of dental plaque. Oxyresveratrol is a natural purification from plants with antibacterial effects on various oral bacteria including Streptococcus mutans. The aim of this study was to investigate the effects of oxyresveratrol on S. gordonii. The basic viability, biofilm formation and cell aggregation of S. gordonii treated with oxyresveratrol were investigated. Oxyresveratrol dose-dependently inhibited the growth of S. gordonii in the absence of sucrose. However, in the presence of sucrose, it promoted biofilm formation under MIC. Both the biofilm formation and extracellular polysaccharides synthesis reached the maximum level at ½ MIC (250 µg/mL) oxyresveratrol. The gene expressions of abpA, abpB, scaA, gtfG, hsa, cshA, cshB, ccpA, srtA and sspB were upregulated when treated with 62.5 and 125 µg/mL oxyresveratrol. A total eight of the ten genes were significantly upregulated at 250 µg/mL oxyresveratrol except abpB and sspB, which were downregulated at 250 µg/mL without significance. In conclusion, oxyresveratrol has dual-effects on S. gordonii. Considering its specific biofilm suppressive effect on S. mutans, it might be a candidate for bacterial interspecies modulator applied in caries prevention.

Radiation-Induced Bystander Effect can be Transmitted Through Exosomes Using miRNAs as Effector Molecules.

The radiation-induced bystander effect (RIBE) is a destructive reaction in nonirradiated cells and is one primary factor in determining the efficacy and success of radiation therapy in the field of cancer treatment. Previously reported studies have shown that the RIBE can be mediated by exosomes that carry miRNA components within. Exosomes, which are one type of cell-derived vesicle, exist in different biological conditions and serve as an important additional pathway for signal exchange between cells. In addition, exosome-derived miRNAs are confirmed to play an important role in RIBE, activating the bystander effect and genomic instability after radiotherapy. After investigating the field of RIBE, it is important to understand the mechanisms and consequences of biological effects as well as the role of exosomes and exosomal miRNAs therein, from different sources and under different circumstances, respectively. More discoveries could help to establish early interventions against RIBE while improving the efficacy of radiotherapy. Meanwhile, measures that would alleviate or even inhibit RIBE to some extent may exist in the near future.

Effects of the natural compound, oxyresveratrol, on the growth of Streptococcus mutans, and on biofilm formation, acid production, and virulence gene expression.

Streptococcus mutans is one of the major pathogens of dental caries. Oxyresveratrol, a natural compound found in plants, exerts inhibitory effects on many bacterial species but its effect on S. mutans is unknown. The objective of this study was to clarify the antibacterial effect of oxyresveratrol on S. mutans, including effects on basic viability, acidogenicity, acidurity, and extracellular polysaccharide synthesis. The expression of nine genes that encode virulence and protective factors in S. mutans was measured by qRT-PCR. Oxyresveratrol showed a dose-dependent inhibitory effect on survival of S. mutans. At 250 µg ml-1 , oxyresveratrol reduced the S. mutans survival rate, inhibited synthesis of water-insoluble glucans, compromised biofilm formation, and significantly down-regulated the expression of glucosyltransferase-I (gtfB) and glucosyltransferase-SI (gtfC). However, the enzymatic activity of lactate dehydrogenase protein was increased and the expression of lactate dehydrogenase (ldh) and ATP synthase subunit beta (atpD) genes were also up-regulated. Besides, glucosyltransferase S (gtfD) up-regulation indicated that water-soluble glucan synthesis was promoted. The vicR, liaR, and comDE genes, which exert a self-protective function in response to external stress, were also up-regulated. In conclusion, oxyresveratrol inhibited the growth of S. mutans and also reduced biofilm formation, acid production, and synthesis of water-insoluble glucans by this organism. In addition, oxyresveratrol also activated a series of S. mutans self-protection mechanisms.

Tobacco and oral squamous cell carcinoma: A review of carcinogenic pathways.

INTRODUCTION: Tobacco is one of the most important risk factors for premature death globally. More than 60 toxic chemicals in tobacco can invade the body's various systems. Oral squamous cell carcinoma (OSCC) is a pathological type of oral cancer, accounting for over 90% of oral cancers. A vast quantity of scientific, clinical and epidemiological data shows that tobacco is associated with the development of oral squamous cell carcinoma, and its carcinogenic pathways may be complicated. METHODS: We conducted a thorough electronic search by Cochrane, EMBASE and PubMed to identify relevant studies. Studies published up to the end of October 2018 were included. After assessing and selecting articles based on eligibility criteria, studies were classified and elaborated according to the pathogenesis. RESULTS: Tobacco as an important risk factor can cause epigenetic alteration of oral epithelial cells, inhibit multiple systemic immune functions of the host, and its toxic metabolites can cause oxidative stress on tissues and induce OSCC. In addition, some specific viruses such as EBV and HPV are thought to play a role in the development of OSCC. CONCLUSIONS: Oral cancer ranks eighth among the most common causes of cancer-related deaths worldwide, and tobacco is one the most important carcinogenic factors of OSCC. This review of the literature attempts to provide directions and ideas for future related research, and emphasizes the need for efforts to reduce tobacco consumption.

Correlation between tobacco smoking and dental caries: A systematic review and meta-analysis.

INTRODUCTION: Tobacco is responsible for infaust oral conditions and many oral diseases. Dental caries is one of the most prevalent oral diseases. The association between tobacco smoking and dental caries has become an important recent topic of research. A systematic review and meta-analysis was conducted to evaluate the association between tobacco smoking and dental caries. METHODS: A literature search was conducted in the databases PubMed, EMBASE, Medline and Cochrane, up to December 2018. Original observational articles that estimated relevance between tobacco smoking and dental caries in adults were included. Caries were determined by measurements of decayed, missing or filled teeth (DMFT), or decayed, missing or filled surface (DMFS), or caries-related microflora levels. Trials did not include a non-smoking group, exposure to smokeless tobacco products, or participants under 16 years old. Also, literature reviews, comments, case reports and letters to the editor were not considered. Both methods of systematic review and meta-analysis were adopted. Newcastle-Ottawa Scale (NOS) was used to assess the methodological quality of all the included studies. RESULTS: Ten out of eleven of the included studies indicated a positive association between tobacco smoking and dental caries. Two meta-analyses were performed: one included five studies using DMFT as an outcome; the other included two studies of DMFS. A random effects model was used. Both were highly heterogeneous (I2=93%, chi-squared p<0.00001; I2=70%, chi-squared p=0.07, respectively) and statistically significant (mean difference, MD=1.20, 95% confidence interval, CI: 0.40-2.00, z-test p=0.003; MD=1.88, 95% CI: 0.99-2.77, z-test p<0.0001, respectively). The quality scores of all varied from 7 to 9. CONCLUSIONS: There is a correlation between tobacco smoking and an increased risk of dental caries. However, the overall representativeness of the studies is not good. More prospective and extensive research on this topic is needed to get validation. Even so, it is imperative that people quit tobacco smoking.

Tea polyphenols: application in the control of oral microorganism infectious diseases.

One of the most popular drinks worldwide, tea is rich in polyphenols and is beneficial to our health because it contributes to the prevention of many diseases. In the human oral cavity, there are more than 750 different species of bacteria living together within dental plaque. Some of the bacteria are pathogens that contribute to the development of oral diseases such as dental caries, periodontitis, pulpitis, mucosal disease, or halitosis through their virulence factors and their metabolites. Until now, many studies have reported that tea polyphenols (TPs) have evident inhibitory effects on some oral pathogenic microorganisms by suppressing pivotal steps of their pathogenic processes. The aim of this review is to summarize the effectiveness and mechanisms of TPs in inhibiting microorganisms, so as to provide new ideas for the prevention and treatment of oral diseases, and to contribute to the global dental public health.