Ultrafine particles exposure is associated with specific operative procedures in a multi-chair dental clinic.

Air quality in dental clinics is critical, especially in light of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic, given that dental professionals and patients are at risk of regular exposure to aerosols and bioaerosols in dental clinics. High levels of ultrafine particles (UFP) may be produced by dental procedures. This study aimed to quantify ultrafine particles (UFP) concentrations in a real multi-chair dental clinic and compare the levels of UFP produced by different dental procedures. The efficiency of a high-volume evacuator (HVE) in reducing the UFP concentrations during dental procedures was also assessed. UFP concentrations were measured both inside and outside of a dental clinic in Shanghai, China during a 12-day period from July to September 2020. Dental activities were recorded during working hours. The mean (±standard deviation) concentrations of indoor and outdoor UFP during the sampling period were 8,209 (±4,407) counts/cm3 and 15,984 (±7,977) counts/cm3, respectively. The indoor UFP concentration was much higher during working hours (10,057 ± 5,725 counts/cm3) than during non-working hours (7,163 ± 2,972 counts/cm3). The UFP concentrations increased significantly during laser periodontal treatment, root canal filling, tooth drilling, and grinding, and were slightly elevated during ultrasonic scaling or tooth extraction by piezo-surgery. The highest UFP concentration (241,136 counts/cm3) was observed during laser periodontal treatment, followed by root canal filling (75,034 counts/cm3), which showed the second highest level. The use of an HVE resulted in lower number concentration of UFP when drilling and grinding teeth with high-speed handpieces, but did not significantly reduce UFP measured during laser periodontal therapy. we found that many dental procedures can generate high concentration of UFP in dental clinics, which may have a great health impact on the dental workers. The use of an HVE may help reduce the exposure to UFP during the use of high-speed handpieces.

Potential apply of hydrogel-carried chlorhexidine and metronidazole in root canal disinfection.

Microorganisms may persist in the root canal system after root canal therapy (RCT). The purpose of this study was to explore the metronidazole (MTR)- and chlorhexidine (CHX)-loaded hydrogels as the potential application in intracanal medicaments for root canal disinfection. Ultraviolet cross-linked hydrogels (gGels) were synthesized by GelMA solution and photoinitiator, which were loaded with MTR (MTR@gGels) and CHX (CHX@gGels). gGels, MTR@gGels and CHX@gGels were characterized by scanning electron microscopy. The antimicrobial activity against E. faecalis, S. mutans and P. intermedia was assessed. Meanwhile, the biocompatibility of human dental pulp stem cells (hDPSCs) was evaluated. DCT, CCK-8, CFU and live/dead-stained biofilm results showed that the viability of E. faecalis, S. mutans and P. intermedia was significantly reduced in MTR@gGels and CHX@gGels in vitro. CCK-8 results showed considerable biocompatibility with hDPSCs. The filling and clearance of gGels in root canals were demonstrated in vivo. Therefore, MTR- and CHX-loaded hydrogels may be a potential application in intracanal medicaments for root canal disinfection.

Berberine ameliorates the LPS-induced imbalance of osteogenic and adipogenic differentiation in rat bone marrow-derived mesenchymal stem cells.

Lipopolysaccharide (LPS) from oral pathogenic bacteria is an important factor leading to alveolar bone absorption and the implant failure. The present study aimed to evaluate the modulation of berberine hydrochloride (BBR) on the LPS-mediated osteogenesis and adipogenesis imbalance in rat bone marrow-derived mesenchymal stem cells (BMSCs). Cell viability, osteoblastic and adipogenic differentiation levels were measured using the Cell Counting Kit-8 assay, alkaline phosphatase (ALP) staining and content assay, and oil red O staining, respectively. Reverse transcription-quantitative PCR and immunoblotting were used to detect the related gene and protein expression levels. In undifferentiated cells, BBR increased the mRNA expression levels of the osteoblastic genes (Alp, RUNX family transcription factor 2, osteocalcin and secreted phosphoprotein 1) but not the adipogenic genes (fatty acid binding protein 4, Adipsin and peroxisome proliferator-activated receptorγ). LPS-induced osteoblastic gene downregulation, adipogenic gene enhancement and NF-κB activation were reversed by BBR treatment. In osteoblastic differentiated cells, decreased ALP production by LPS treatment was recovered with BBR co-incubation. In adipogenic differentiated cells, LPS-mediated lipid accumulation was decreased by BBR administration. The mRNA expression levels of the pro-inflammatory factors (MCP-1, TNF-α, IL-6 and IL-1ß) were increased by LPS under both adipogenic and osteoblastic conditions, which were effectively ameliorated by BBR. The actions of BBR were attenuated by compound C, suggesting that the role of BBR may be partly due to AMP-activated protein kinase activation. The results demonstrated notable pro-osteogenic and anti-adipogenic actions of BBR in a LPS-stimulated inflammatory environment. This indicated a potential role of BBR for bacterial infected-related peri-implantitis medication.

Leonurine Promotes the Osteoblast Differentiation of Rat BMSCs by Activation of Autophagy via the PI3K/Akt/mTOR Pathway.

BACKGROUND: Leonurine, a major bioactive component from Herba leonuri, has been shown to exhibit anti-inflammatory and antioxidant effects. The aim of this study was to investigate the effect of leonurine on bone marrow-derived mesenchymal stem cells (BMSCs) as a therapeutic approach for treating osteoporosis. MATERIALS AND METHODS: Rat bone marrow-derived mesenchymal stem cells (rBMSCs) were isolated from 4-weeks-old Sprague-Dawley rats. The cytocompatibility of leonurine on rBMSCs was tested via CCK-8 assays and flow cytometric analyses. The effects of leonurine on rBMSC osteogenic differentiation were analyzed via ALP staining, Alizarin red staining, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot. Additionally, autophagy-related markers were examined via qRT-PCR and Western blot analyses of rBMSCs during osteogenic differentiation with leonurine and with or without 3-methyladenine (3-MA) as an autophagic inhibitor. Finally, the PI3K/Akt/mTOR signaling pathway was evaluated during rBMSC osteogenesis. RESULTS: Leonurine at 2-100 µM promoted the proliferation of rBMSCs. ALP and Alizarin red staining results showed that 10 µM leonurine promoted rBMSC osteoblastic differentiation, which was consistent with the qRT-PCR and Western blot results. Compared with those of the control group, the mRNA and protein levels of Atg5, Atg7, and LC3 were upregulated in the rBMSCs upon leonurine treatment. Furthermore, leonurine rescued rBMSC autophagy after inhibition by 3-MA. Additionally, the PI3K/AKT/mTOR pathway was activated in rBMSCs upon leonurine treatment. CONCLUSION: Leonurine promotes the osteoblast differentiation of rBMSCs by activating autophagy, which depends on the PI3K/Akt/mTOR pathway. Our results suggest that leonurine may be a potential treatment for osteoporosis.

Expression of autophagy­associated proteins in rat dental irreversible pulpitis.

Autophagy serves an important role in numerous diseases, as well as in infection and inflammation. Irreversible pulpitis (IP) is one of the most common inflammatory endodontic diseases, and autophagy has been reported to regulate IP in vitro. However, the level of autophagy in the IP pathogenic process in vivo remains unknown. The aim of the current study was, thus, to investigate the levels of autophagy­associated proteins in rats with IP in vivo. A rat dental IP model was successfully constructed, and five different time points (0, 1, 3, 5 and 7 days) were investigated. The levels of the autophagy­related 5 (ATG5), ATG7, light chain 3 (LC3) and Beclin­1 proteins exhibited a time­dependent increase in rats with IP, whereas the levels of mammalian target of rapamycin and p62/sequestosome 1 were decreased. In addition, the levels of ATG proteins were specifically increased in odontoblasts and microvascular endothelial cells in pulpitis tissue. Based on these findings, autophagy may serve an important role in IP, and the present study data provide a new insight into the IP pathogenesis and treatment.

Role of protein delta homolog 1 in the proliferation and differentiation of ameloblasts.

Protein delta homolog 1 (DLK1) regulates the odontoblastic differentiation of human dental pulp stem cells. It was hypothesized that DLK1 may exert regulatory effects on epithelial­mesenchymal interactions in tooth development. The present study investigated the expression of DLK1 during the development of mouse enamel and its role in the proliferation and differentiation of ameloblast­lineage cells (ALCs). DLK1 expression was upregulated in ameloblasts in the first mandibular molar during the entire process of enamel development. The mRNA and protein levels of DLK1 were significantly upregulated following ameloblastic induction in ALCs. In addition, overexpression of DLK1 promoted the proliferation of ALCs, inhibited ameloblastic differentiation, upregulated the expression of amelogenin and enamelin, and downregulated the expression of odontogenic ameloblast­associated protein and kallikrein 4. The results of the present study suggested that DLK1 may be a potent regulator of ameloblast proliferation and differentiation, and may regulate enamel formation during tooth development.

Effect of CRABP2 on the proliferation and odontoblastic differentiation of hDPSCs.

Cellular retinoic acid-binding protein 2 (CRABP2) has been detected in several organs during embryonic development. Recent studies have demonstrated that CRABP2 plays important roles in the retinoic acid, ß-catenin and Notch signaling pathways, as well as in the interaction between epithelial and mesenchymal cells, which are important for human dental pulp stem cells (hDPSCs) and tooth development. In the present study, the expression of CRABP2 during mouse molar development and the role of CRABP2 in hDPSC odontoblastic differentiation were evaluated. CRABP2 was gradually decreased during the development of the first maxillary molar, which exhibited the same trend as the expression of CRABP2 during the odontoblastic induction of hDPSCs. CRABP2 knockdown inhibited the proliferative ability of hDPSCs, while it enhanced odontoblastic differentiation via promoting mineralization nodule formation and upregulating the activity of alkaline phosphatase and the expression of mineralization-related genes. The present study uncovered a novel function of CRABP2 in hDPSCs. Our data suggest that CRABP2 may act as a regulator during the proliferation and differentiation of hDPSCs.

The effect of delta-like 1 homologue on the proliferation and odontoblastic differentiation in human dental pulp stem cells.

INTRODUCTION: This study aimed to investigate the functions of delta-like homologue 1 (DLK1) in the proliferation and differentiation of human dental pulp stem cells (hDPSCs). METHODS: Immunohistochemical analysis was used to determine the expression of alkaline phosphatase (ALP), dentin sialophosphoprotein (DSPP), DLK1, NOTCH1 and p-ERK1/2 in the mouse first maxillary molar. Recombinant lentivirus was constructed to overexpress DLK1 stably in hDPSCs. The cell viability and proliferation of hDPSCs were examined by CCK8 and EdU incorporation assay respectively. The odontoblastic differentiation of hDPSCs was determined by detection of ALPase activity assay, ALP and alizarin red staining and the expression of mineralization-related genes including ALP, DSPP and dental matrix protein. The mRNA and protein levels of DLK1 and p-ERK1/2 protein expression were detected. ERK inhibitor was used to test the differentiation effect of DLK1 on hDPSCs. RESULTS: Delta-like homologue 1 was highly expressed on the odontoblasts and dental pulp cells on the first maxillary molar; the expression of p-ERK1/2 is similar with the DLK1 in the same process. The expression level of DLK1 increased significantly after the odontoblastic induction of hDPSCs. DLK1 overexpression increased the proliferation ability of hDPSCs and inhibited odontoblastic differentiation of hDPSCs. The protein level of p-ERK1/2 significantly increased in hDPSCs/dlk1-oe group. ERK signalling pathway inhibitor reversed the odontoblastic differentiation effects of DLK1 on hDPSCs. CONCLUSIONS: The proliferation of hDPSCs was promoted after DLK1 overexpression. DLK1 inhibited the odontoblastic differentiation of hDPSCs, which maybe through ERK signalling pathway.

Effect of CRABP2 on the proliferation and odontoblastic differentiation of hDPSCs

Abstract: Cellular retinoic acid-binding protein 2 (CRABP2) has been detected in several organs during embryonic development. Recent studies have demonstrated that CRABP2 plays important roles in the retinoic acid, β-catenin and Notch signaling pathways, as well as in the interaction between epithelial and mesenchymal cells, which are important for human dental pulp stem cells (hDPSCs) and tooth development. In the present study, the expression of CRABP2 during mouse molar development and the role of CRABP2 in hDPSC odontoblastic differentiation were evaluated. CRABP2 was gradually decreased during the development of the first maxillary molar, which exhibited the same trend as the expression of CRABP2 during the odontoblastic induction of hDPSCs. CRABP2 knockdown inhibited the proliferative ability of hDPSCs, while it enhanced odontoblastic differentiation via promoting mineralization nodule formation and upregulating the activity of alkaline phosphatase and the expression of mineralization-related genes. The present study uncovered a novel function of CRABP2 in hDPSCs. Our data suggest that CRABP2 may act as a regulator during the proliferation and differentiation of hDPSCs.

A novel model of bisphosphonate-related osteonecrosis of the jaw in rats.

OBJECTIVE: To establish a rat model of bisphosphonate-related osteonecrosis of the jaw (BRONJ) that realistically mimics major clinical manifestations of the disease. METHODS: Female Sprague Dawley rats received intravenous zoledronate 80 µg/kg once a week via the tail vein. Three weeks after intravenous injection, maxillary first molars were extracted under general anesthesia. Then 1, 4 and 12 weeks after tooth extraction, the rats were euthanized, and the intact maxillas were harvested en bloc. Macroscopic analysis, histological analysis and cytokine analysis were performed. Untreated rats with tooth extraction were used as controls. RESULTS: 12 weeks after extraction, rats treated with zoledronate developed BRONJ-like disease, including characteristic features of impaired soft tissue healing, exposed necrotic bone or sequestra, increased inflammatory infiltrates, while the controls showed normal bone healing. 4 weeks after extraction, rats treated with zoledronate exhibited the decreased receptor activator of nuclear factor kappa-B ligand (RANKL) values, the increased osteoprotegerin (OPG) values and the remarkable decreased RANKL/OPG ratio when compared with the controls. CONCLUSION: The rats treated with zoledronate can be considered a novel, reliable and reproducible animal model to better understand the pathophysiology and pathogenesis of BRONJ and to develop a therapeutic approach.

Osteogenesis of bone marrow mesenchymal stem cells on strontium-substituted nano-hydroxyapatite coated roughened titanium surfaces.

OBJECTIVE: To investigate osteogenesis of bone marrow mesenchymal stem cells (BMSCs) on strontium-substituted nano-hydroxyapatite (Sr-HA) coated roughened titanium surfaces. METHODS: Sr-HA coating and HA coating were fabricated on roughened titanium surfaces by electrochemical deposition technique and characterized by field emission scanning electron microscope (FESM). BMSCs were cultured on Sr-HA coating, HA coating and roughened titanium surfaces respectively. Cell proliferation, alkaline phosphatase (ALP) activity, mineralized nodules formation and cell osteocalcin (OC) secretion were measured. RESULTS: Electrochemically deposited Sr-HA coating and HA coating had no effect on the proliferation of BMSCs and demonstrated that the materials have a good biocompatibility. BMSCs cultured on Sr-HA coating showed increased alkaline phosphatase activity, mineralized nodules formation, and cell OC secretion compared with the other two groups. Cells cultured on HA coating also showed increased biological activity compared with the roughened group. CONCLUSION: Sr-HA coated titanium surfaces by electrochemical deposition can promote osteogenesis of BMSCs in vitro and have the potential to shorten bone healing period and enhance implant osseointegration.

The correlations between health-related quality of life changes and pain and anxiety in orthodontic patients in the initial stage of treatment.

This study aimed to assess generic health-related quality of life (HRQoL), pain intensity, and anxiety levels and the relationship between the three aspects in healthy young Chinese orthodontic patients in the early stage of orthodontic treatment. We enrolled 252 eligible participants (10-29 years old) to complete validated Chinese versions of questionnaires, including the State-Trait Anxiety Inventory (S-AI), the visual analogue scale (VAS), and the Short-Form 36-Item Health Survey (SF-36) at baseline and on days 1, 2, 3, 7, 14, and 30 after initial archwire placement (SF-36 only at baseline and day 30). The response rate was 96% (243 of 252). SF-36 had moderate reliability (Cronbach's alpha coefficient exceeding 0.7, good fit on day 30). Statistical significant changes were observed in physical function (P < 0.01), body pain (P = 0.01), and general health (P < 0.01) domains. Spearman correlation coefficients for SF-36 with S-AI were -0.131~-0.515 (P < 0.05); SF-36 with VAS were -0.141~-0.273 (P < 0.05), indicating significant but moderate negative correlations between HRQoL and pain/anxiety. Overall, the application of SF-36 in assessing HRQoL is reluctantly suitable for young Chinese orthodontic patients in the early stage of orthodontic treatment. Early treatment-related pain and anxiety are important factors in HRQoL.

Effect of estrogen deficiency on implant osseointegration in dogs.

PURPOSE: This study investigated the effect of the absence of estrogen on the process of implant osseointegration in the jaws of beagle dogs. MATERIALS AND METHODS: Of eight beagle dogs, four underwent bilateral ovariectomy (OVX), and the other four constituted a control group. Twelve weeks postsurgery, XiVE implants (Dentsply) were placed in the second premolar site in the mandible and in the canine site in the maxilla. Zero, 4, 8, 12, and 16 weeks after implant placement, implant stability quotients (ISQs) were measured by resonance frequency analysis (RFA). RESULTS: The blood estrogen levels 12 weeks postsurgery were 5.8 ± 1.8 pg/mL in the OVX group and 37.0 ± 2.9 pg/mL in the control group, which represents a significant decrease (P < .01). The ISQ of maxillary implants in the OVX group 12 weeks after implant placement was 64.5 ± 1.7, and in the control group it was 74.3 ± 1.5; the ISQ was significantly reduced in the OVX group (.01 < P < .05). CONCLUSION: The results of this study indicate that the absence of estrogen induced by OVX in beagle dogs could reduce osseointegration around maxillary implants but has little influence in the mandible.

The properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and its applications in tissue engineering.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is a member of the polyhydroxyalkanoate (PHA) family. It is the designation of molecules consisting of random co-polymers of 3-hydroxybutyrate and 3- hydroxyhexanoate. PHBHHx plays a significant role in the field of biomedical materials. It has good physical, chemical and mechanical properties, making it potentially useful for a wide range of biomaterials applications. In addition, it has also shown better biocompatibility with different cell types. This paper will introduce the physical, chemical and biological properties of PHBHHx, including biodegradation, hydrophilicity, surface properties and cytocompatibility. The development of PHBHHx in tissue-engineering applications will be discussed. PHBHHx used to repair bone, cartilage, tendons, nerves and vessels will be the focus of discussion.

Review of and perspectives on the toxicology of graphene-based materials.

Graphene possesses a wide range of potential biomedical applications because of the unique physical and chemical properties. However, the side effects of grapheme and its derivatives on a number of biological models even on human body are still not very clear. Therefore, to properly assess the potential risk of grapheme and its derivatives, we summarize the current state of academic knowledge on their toxicity.

[The disinfecting effect of ozone on four kinds of bacteria].

PURPOSE: To evaluate the disinfecting effect of ozone on 4 kinds of bacteria: Staphylococcus aureus, Streptococcus mutans, Staphylococcus epidermidis and Streptococcus pneumoniae. METHODS: The concentration of ozone that was transmitted by ozone generator at different time was determined by using iodine titrimetric method. According to the bactericidal assay of quantitative vehicle, the bacteria on the ozonized vehicles and unozonized vehicles was washed, 50 microl eluant was seeded on the TSA plates. The TSA plates were put into the anaerobiotic incubator (90% N(2),10% CO(2),37 degrees centigrade). After 24 to 48 hours, the CFU on the plate was counted.The data was analyzed by one-way ANOVA with SAS 6.12 software package. RESULTS: The sterilization effect depended on the ozone concentration and the treatment time. When the 4 kinds of bacteria were treated with 2.73 mg/L ozone for 45 minutes, there was no bacteria alive. CONCLUSIONS: Ozone has obvious disinfecting effect on the 4 kinds of bacteria and the effect is correlated with the concentration of ozone.

Histological assessments on the abnormalities of mouse epiphyseal chondrocytes with short term centrifugal loading.

We have examined the morphological changes in chondrocytes after exposure to experimental hypergravity. Tibial epiphyseal cartilages of 17-days-old mouse fetuses were exposed to centrifugation at 3G for 16 h mimicking hypergravitational environment (experimental group), or subjected to stationary cultures (control group). Centrifugation did not affect the sizes of epiphyseal cartilage, chondrocyte proliferation, type X collagen-positive hypertrophic zone, and the mRNA expressions of parathyroid hormone-related peptide and fibroblast growth factor receptor III. However, centrifuged chondrocytes showed abnormal morphology and aberrant spatial arrangements, resulting in disrupted chondrocytic columns. Through histochemical assessments, actin filaments were shown to distribute evenly along cell membranes of control proliferative chondrocytes, while chondrocytes subjected to centrifugal force developed a thicker layer of actin filaments. Transmission electron microscopic observations revealed spotty electron-dense materials underlying control chondrocytes' cell membranes, while experimental chondrocytes showed their thick layer. In the intracolumnar regions of the control cartilage, longitudinal electron-dense fibrils were associated with short cytoplasmic processes of normal chondrocytes, indicating assumed cell-tomatrix interactions. These extracellular fibrils were disrupted in the centrifuged samples. Summarizing, altered actin filaments associated with cell membranes, irregular cell shape and disappearance of intracolumnar extracellular fibrils suggest that hypergravity disturbs cell-to-matrix interactions in our cartilage model.

[Ultrasonic atomization of Shaduolika and dexamethasone for pain relief in patients with foliate papillitis].

PURPOSE: To evaluate the effect of ultrasonic atomization of Shaduolika (a traditional Chinese herb), dexamethasone for pain relief in patients with foliate papillitis. METHODS: 84 patients with foliate papillitis were divided into two groups randomly with the single-blind method. Patients in the experimental group were treated with ultrasonic atomization of Shaduolika and dexamethasone, while patients in the control group were treated by taking Niuhuangjiedu tablets (mixed traditional Chinese medicine). All the patients were observed for five days. Pain relief degree by VAS and the response to the interventions between the experimental and the control group were recorded and compared. The data was analyzed with Ridit test, Chi-square test and Student's t test using SAS6.12 software package, respectively. RESULTS: Pain scores between the experimental and the control group prior to treatment had no significant difference (U=0.1859<1.96, P>0.05), while significant difference existed in pain relief after treatment (U=5.773, P<0.01). The effect of ultrasonic atomization of Shaduolika and dexamethasone for pain relief was significantly better than the control group (U=5.233,P<0.01). CONCLUSIONS: For patients with foliate papillitis, ultrasonic atomization of Shaduolika and dexamethasone is a safe and effective method.