An experimental study of a novel external fixator based on universal joints for the rapid initial stabilization of mandibular comminuted fractures.

PURPOSE: Shaping and assembling contemporary external fixators rapidly for the severe mandibular fractures remains a challenge, especially in emergency circumstance. We designed a novel external fixator that incorporates universal joints to provide the stabilization for mandibular comminuted fractures. This study aims to confirm the efficacy of this novel external fixator through biomechanical tests in vitro and animal experiments. METHODS: In vitro biomechanical tests were conducted using 6 fresh canine with mandibular defect to simulate critical comminuted fractures. Three mandibles were stabilized by the novel external fixator and other mandibles were fixed by 2.5 mm reconstruction plates. All fixed mandibles were subjected to loads of 350 N on the anterior regions of teeth and 550 N on the first molar of the unaffected side. The stability was evaluated based on the maximum displacement and the slope of the load-displacement curve. In animal experiments, 9 beagles with comminuted mandibular fractures were divided into 3 groups, which were treated with novel external fixation, reconstruction plate, and dental arch bar, respectively. The general observation, the changes in animals' weight, and the surgical duration were recorded and compared among 3 groups. The CT scans were performed at various intervals of 0 day (immediately after the surgery), 3 days, 7 days, 14 days, 21 days, and 28 days to analyze the displacement of feature points on the canine mandible and situation of fracture healing at 28 days. The statistical significance was assessed by the two-way analysis of variance test followed by the Bonferroni test, enabling multiple comparisons for all tests using GraphPad Prism10.1.0 (GraphPad Inc, USA). RESULTS: The outcomes of the biomechanical tests indicated that no statistically significant differences were found in terms of the maximum displacement (p = 0.496, 0.079) and the slope of load displacement curves (p = 0.374, 0.349) under 2 load modes between the external and internal fixation groups. The animal experiment data showed that there were minor displacements of feature points between the external and internal fixation groups without statistic difference, while the arch bar group demonstrated inferior stability. The CT analysis revealed that the best fracture healing happened in the internal fixation group, followed by the external fixation and arch baring at 28 days after fixation. The external fixation group had the shortest fixation duration (25.67 ± 3.79) min compared to internal fixation ((70.67 ± 4.51) min, p < 0.001) and arch baring ((42.00 ± 3.00) min, p = 0.046). CONCLUSION: The conclusion of this study highlighted the efficacy and reliability of this novel external fixator in managing mandibular fractures rapidly, offering a viable option for the initial stabilization of comminuted mandibular fractures in the setting of emergency rescue.

Effects of short-term orthodontic force application on the root at different developmental stages in rat maxillary molars.

INTRODUCTION: The suitable timing and duration of orthodontic force to be applied to teeth with developing roots are unclear. We investigated the effects of short-term orthodontic force application on the roots at different root developmental stages in rats to predict the optimal timing for orthodontic treatment of teeth with developing roots. METHODS: Light orthodontic force was applied on the maxillary first molars of rats from postnatal day (PN) 21 or PN28 for 3 days. After that, the force was released, and the roots were evaluated on PN35 to determine the root length, apical morphology, and cell proliferation of the maxillary first mesial roots using microcomputed tomography and histologic evaluation. RESULTS: When a light orthodontic force was applied from PN21, the root length did not differ from that in age-matched controls. In addition, after the force was released, the roots attained the normal root-completing length and had a well-formed root apical morphology at PN35. Conversely, when the force was applied from PN28, the roots showed apical abnormalities characterized by deformed dentin and disorganized arrangement of odontoblasts, reduced apical cell proliferation, and significantly shorter length than those in the age-matched controls at PN31. The shortened root and disturbed apical integrity could not be rescued by releasing the orthodontic force at PN35. CONCLUSIONS: Short-term orthodontic force at the late and slow root developmental stage results in a shortened root and a defect in the root apex with reduced cell proliferation. Our findings support that orthodontic force for a limited duration during the active and rapid root developmental stage is more favorable than during the late and slow stage.

3D printing of dual-cell delivery titanium alloy scaffolds for improving osseointegration through enhancing angiogenesis and osteogenesis.

BACKGROUND: The repair of large bone defects is a great challenge for orthopedics. Although the development of three-dimensional (3D) printed titanium alloy (Ti6Al4V) implants with optimized the pore structure have effectively promoted the osseointegration. However, due to the biological inertia of Ti6Al4Vsurface and the neglect of angiogenesis, some patients still suffer from postoperative complications such as dislocation or loosening of the prosthesis. METHODS: The purpose of this study was to construct 3D printed porous Ti6Al4V scaffolds filled with bone marrow mesenchymal stem cells (BMSC) and endothelial progenitor cells (EPC) loaded hydrogel and evaluate the efficacy of this composite implants on osteogenesis and angiogenesis, thus promoting osseointegration. RESULTS: The porosity and pore size of prepared 3D printed porous Ti6Al4V scaffolds were 69.2 ± 0.9 % and 593.4 ± 16.9 µm, respectively, which parameters were beneficial to bone ingrowth and blood vessel formation. The BMSC and EPC filled into the pores of the scaffolds after being encapsulated by hydrogels can maintain high viability. As a cell containing composite implant, BMSC and EPC loaded hydrogel incorporated into 3D printed porous Ti6Al4V scaffolds enhancing osteogenesis and angiogenesis to repair bone defects efficiently. At the transcriptional level, the composite implant up-regulated the expression levels of the osteogenesis-related genes alkaline phosphatase (ALP) and osteocalcin (OCN), and angiogenesis-related genes hypoxia-inducible factor 1 alpha (HIF-1α), and vascular endothelial growth factor (VEGF). CONCLUSIONS: Overall, the strategy of loading porous Ti6Al4V scaffolds to incorporate cells is a promising treatment for improving osseointegration.

Preparation and evaluation of bis(diallyl alkyl tertiary ammonium salt) polymer as a promising adsorbent for phosphorus removal.

Problems associated with water eutrophication due to high phosphorus concentrations and related environmentally safe solutions have attracted wide attention. A novel bis(diallyl alkyl tertiary ammonium salt) polymer, particularly poly(N1,N1,N6,N6-tetraallylhexane-1,6-diammonium dichloride) (PTAHDADC), was synthesized and characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, mercury intrusion method, and thermogravimetric analysis. The adsorption characteristics in phosphorus were evaluated in dilute solution, and the recycling properties of PTAHDADC were investigated. Results showed that PTAHDADC possessed macropores with a size distribution ranging from 30 to 130 µm concentrating at 63 µm in diameter and had 46.52% of porosity, excellent thermal stability below 530K, and insolubility. PTAHDADC could effectively remove phosphorus at pH = 7-11 and had a removal efficiency exceeding 98.4% at pH = 10-11. The adsorption equilibrium data of PTAHDADC for phosphorus accorded well with the Langmuir and pseudo-second-order kinetic models. Maximum adsorption capacity was 52.82 mg/g at 293 K. PTAHDADC adsorbed phosphorus rapidly and reached equilibrium within 90 min. Calculated activation energy Ea was 15.18 kJ/mol. PTAHDADC presented an excellent recyclability with only 8.23% loss of removal efficiency after five adsorption-desorption cycles. The morphology and structure of PTAHDADC slightly changed as evidenced by the pre- and post-adsorption of phosphorus, but the process was accompanied by the partial deprotonation of the (-CH2)3NH+ group of PTAHDADC. The adsorption was a spontaneous exothermic process driven by entropy through physisorption, electrostatic attraction, and ion exchange. Survey results showed that PTAHDADC was a highly efficient and fast-adsorbing phosphorus-removal material prospective in treating wastewater.

Self-assembled core-shell nanoparticles with embedded internal standards for SERS quantitative detection and identification of nicotine released from snus products.

Surface enhanced Raman spectroscopy (SERS) is a unique analytical technique with excellent performance in terms of sensitivity, non-destructive detection and resolution. However, due to the randomness and poor repeatability of hot spot distribution, SERS quantitative analysis is still challenging. Meanwhile, snus is a type of tobacco product that can release nicotine and other components in the mouth without burning, and the rapid detection technique based on SERS can reliably evaluate the amount of nicotine released from snus, which is of great significance for understanding its characteristics and regulating its components. Herein, the strategy was proposed to solve the feasibility of SERS quantitative detection based on self-assembled core-shell nanoparticles with embedded internal standards (EIS) due to EIS signal can effectively correct SERS signal fluctuations caused by different aggregation states and measurement conditions, thus allowing reliable quantitative SERS analysis of targets with different surface affinity. By means of process control, after the Au nanoparticles (Au NPs) were modified with 4-Mercaptobenzonitrile (4-MBN) as internal standard molecules, Ag shell with a certain thickness was grown on the surface of the AuNP@4-MBN, and then the Au@4-MBN@Ag NPs were used to regulate and control the assembly of liquid-liquid interface. The high-density nano-arrays assembled at the liquid-liquid interface ensure high reproducibility as SERS substrates, and which could be used for SERS detection of nicotine released from snus products. In addition, time-mapping research shows that this method can also be used to dynamically monitor the release of nicotine. Moreover, such destruction-free evaluation of the release of nicotine from snus products opens up new perspectives for further research about the impact of nicotinoids-related health programs.

Inhibition of circular RNA circ_0138959 alleviates pyroptosis of human gingival fibroblasts via the microRNA-527/caspase-5 axis.

Circular RNA (circRNA) plays a regulatory role in periodontitis. This study explored whether circ_0138959 affected lipopolysaccharide (LPS)-induced pyroptosis in human gingival fibroblasts (HGFs). The periodontal ligament (PDL) tissues and HGFs were derived from patients with periodontitis and healthy volunteers. HGFs treated with LPS were considered to mimic periodontitis in vitro. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to evaluate the mRNA expression levels of circRNAs, miR-527, and caspase-5 (CASP5), and Western blotting assay was used to measure protein expression levels of caspase-1, caspase-4, and cleaved N-terminal gasdermin D (GSDMD-N). Cell viability was evaluated by cell counting kit-8 (CCK-8) assay. The concentration of lactate dehydrogenase (LDH), interleukin (IL)-1ß, and IL-18 and the pyroptosis rate were determined to evaluate pyroptosis. The interaction between miR-527 and circ_0138959 or CASP5 was verified by dual-luciferase reporter and RNA pull-down assays. Circ_0138959 expression was higher in the PDL tissues of patients with periodontitis than in the healthy group; likewise, circ_0138959 was also upregulated in LPS-treated HGFs. Suppressed circ_0138959 increased cell viability and decreased pyroptosis of HGFs induced by LPS. miR-527 was a target of circ_0138959, and inhibition of miR-527 contributed to the dysfunction of LPS-treated HGFs and reversed the protective effects of downregulated circ_0138959. Additionally, miR-527 targeted CASP5. Increased CASP5 abrogated the effects of overexpressed miR-527 on cell viability and pyroptosis of LPS-treated HGFs. Inhibition of circ_0138959 promoted cell viability and suppressed pyroptosis of HGFs via the miR-527/CASP5 axis. Therefore, knockdown of circ_0138959 may be a promising therapy for periodontitis.

The Expression of miR-34a in Gingival Crevicular Fluid of Chronic Periodontitis and Its Connection with the TLR/NF-κB Signaling Pathway.

Objective: This study analyzed the expression of miR-34a in gingival crevicular fluid (GCF) of patients with chronic periodontitis and its connection with the Toll-like receptor (TLR)/nuclear factor kappa-B (NF-κB) signaling pathway. Methods: We collected the GCF of the two groups of subjects, using RT-PCR to detect the expression of miR-34a and NF-κB p65 mRNA and TLR4 mRNA and ELISA to detect the inflammatory factor degree in GCF, and performed periodontal examinations on both groups. Results: The gingival index, bleeding index, probe depth, and attachment loss indexes of periodontal examination in the observation group were remarkably superior to those in the control group (P < 0.05). The levels of IL-1ß, IL-6, and TNF-α in the GCF of the observation group were higher than those of the control group (P < 0.05). The mRNA relative expression levels of miR-34a, NF-κB p65, and TLR4 in the GCF of the observation group were dramatically higher than those of the control group (P < 0.05). Correlation analysis showed that miR-34a was highly expressed in patients with chronic periodontitis. Conclusion: There is an abnormally high expression of miR-34a in GCF of chronic periodontitis. Its expression is associated with the degree of periodontal inflammation, periodontal tissue damage, and the activation of the TLR/NF-κB signaling pathway and could be used as a potential index for auxiliary diagnosis and severity of the disease.

Isolation and Culture of Bone Marrow Mesenchymal Stem Cells from the Human Mandible.

Human mesenchymal stem cells (hMSCs) have shown great potential in bone regeneration, immune modulation, and treating refractory chronic diseases. Various origins have been found to obtain hMSCs recently, while bone marrow was still considered the main source. Bone marrow-derived MSCs (BMSCs) from different donor bone sites have distinct characteristics due to microenvironmental factors. Studies have shown that BMSCs from maxillofacial bone may have greater proliferative and osteogenic capacities than BMSCs from long bones or the iliac crest. And maxillofacial BMSCs were considered more suitable for stem cell therapy in the maxillofacial tissues. The mandible, especially the ascending ramal area with sufficient marrow, was a feasible donor site for harvesting BMSCs. This study described a protocol for harvesting, isolating, and culturing human mandibular bone marrow-derived MSCs (hmBMSCs). Furthermore, immunophenotyping of hmBMSCs, proliferation assays, and in vitro induction of osteogenic, adipogenic, and chondrogenic differentiation was performed to identify the cultured cells. Applying this protocol can help the researchers successfully obtain enough high-quality hmBMSCs, which is necessary for further studies of the biological function, microenvironmental effects, and clinical applications.

Computed Tomography Three-Dimensional Reconstruction Algorithm in the Diagnosis of Periodontitis and Its Correlation with Hypertension.

This study was aimed at exploring the value of iterative reconstruction (IR) algorithm to treat the periodontitis using computed tomography (CT) image and analyze the relationship between periodontitis and hypertension. 95 patients with periodontitis were selected, including 43 patients with periodontitis, 41 patients with advanced periodontitis and hypertension, and 11 patients with periodontitis and nonhigh blood pressure (NBP). The IR algorithm was introduced to the CT image scanning of them to reduce the noise. In addition, the CT value was statistically analyzed. High-sensitivity C-reactive protein (hs-CRP) and interleukin 6 (IL-6) were dramatically increased compared with periodontitis patients with NBP and with hypertension (P < 0.05). After the IR algorithm of the image, the quality, information, and mean square error (MSE) of the image were all effectively improved. Image with a 50% dose showed the lowest noise, but the reconstruction algorithm improved the low-contrast resolution. Moderate and severe periodontitis was independently related to hypertension. Inflammatory cytokines were independently related to hypertension of periodontitis patients (P < 0.05). Therefore, it was concluded that the IR algorithm could effectively improve the spatial resolution of the CT image when it was adopted to treat periodontitis and showed a high accuracy rate; the incidence of hypertension in patients with periodontitis was relatively high, and it had a certain relationship with periodontitis; and inflammatory cytokines were related to periodontitis and hypertension of patients.

Stem Cells from Human Exfoliated Deciduous Teeth Ameliorate Autistic-Like Behaviors of SHANK3 Mutant Beagle Dogs.

Mesenchymal stem cell-based therapy has emerged as a great potential approach to treat individuals with autism spectrum disorders (ASD), a group of developmental disabilities characterized by impairments in social interaction and communication. Stem cells from human exfoliated deciduous teeth (SHED), holding earlier developing characteristics, have immune-modulatory and anti-inflammatory properties. To investigate whether SHED transplantation can rescue autistic-like symptoms in SHANK3 mutant beagle dogs, 12 SHANK3 mutant beagle dogs were randomly assigned into 2 groups according to their behavior evaluated by social interaction tests. Six mutant dogs received 6 intravenous infusions of SHED and were followed up for 3 months by testing social interaction and inflammatory cytokine levels. We found that infusion of SHED significantly improved impaired social novel preference of SHANK3 mutant beagle dogs at 1- and 3-month follow-ups. Social intimacies (following, sniffing, and licking) between mutant beagle dogs and human experimenters were partly improved. Stressed tail posture, indicating social stress, was also significantly alleviated. In addition, we showed that the levels of serum interferon-γ and interleukin-10 were notably increased and decreased, respectively, in SHANK3 mutant beagle dogs. Infusion of SHED was able to rescue altered interferon-γ and interleukin-10 levels. We failed to observe any serious adverse events after infusion of SHED. In summary, SHED transplantation may be a safe and effective therapy for ASD. The correction in the levels of serum interferon-γ and interleukin-10 may serve as an index to predict autistic severity and therapeutic outcomes.

Structural characterization of lignin and lignin-carbohydrate complex (LCC) of sesame hull.

In the present study, lignin and lignin-carbohydrate complex (LCC) constituting the cell wall structure of sesame hulls were investigated to explore novel techniques of dehulling. Milled wood lignin (MWL), Björkman LCC, and acid-soluble LCC (LCC-AcOH) were extracted from sesame hulls and characterized by carbohydrate composition analysis, molecular weight analysis, UV-vis spectroscopy, FT-IR, thermal analysis, Py-GC/MS, 2D HSQC NMR, and 31P NMR. The results showed that rhamnose accounted for the largest proportion of the lignin and LCC fractions, followed by glucose. Björkman LCC had the largest molecular weight, MWL had the smallest molecular weight, and LCC-AcOH had the largest polydispersity index. The lignin of sesame hulls consisted of syringyl (S), guaiacyl (G), p-hydroxyphenyl (H), and caffeyl alcohol (C) units. The most abundant monomer was guaiacyl (G), followed by caffeyl alcohol (C). C-type lignin is a new type of lignin that is different from the three traditional lignin monomers. The major lignin-linked bonds in the MWL and LCC-AcOH were ß-O-4' and ß-ß', and ß-5' bonds were present in the Björkman LCC. The major LCC chemical bonds in the three fractions were PhGly. These findings will provide the factual basis for exploring different dehulling methods to enhance the quality of sesame products.

Effects of a helium cold atmospheric plasma on bonding to artificial caries-affected dentin.

This study investigated the effects of a helium cold atmospheric plasma (CAP) on the bonding performance and surface modification of the caries-affected dentin (CAD). Artificial CAD was created by pH-cycling. The microtensile bond of CAD were examined before and after CAP treatments at 24 h and after 2-year aging. The effects of surface modification were studied with contact-angle measurement, scanning electron microscopy and X-ray photoemission spectroscopy. Thirty-second CAP treatment increased the immediate bond strength of CAD to a level that was statistically the same as sound dentin, and slowed the aging process of the bonding as well. The CAP treatment induced modified CAD surface with increased wettability, cleaner appearance, and increased percentage of the mineral-associated elements and oxygen. This research demonstrated that the helium CAP jet treatments of 30 s and 45 s improved the bond strength of the artificial CAD, and was considerably effective in its surface modification.

Effect of non-surgical periodontal therapy on the levels of Th17/Th1/Th2 cytokines and their transcription factors in Chinese chronic periodontitis patients.

AIM: A new subset of CD4(+) T cells, Th17, has been recently discovered independent from Th1/Th2 paradigm. The aim of this study was to investigate the effects of non-surgical periodontal therapy on the expression of Th17/Th1/Th2 cytokines and transcription factors, and Th17 cell vibration in Chinese chronic periodontitis patients. MATERIALS AND METHODS: The levels of Th17/Th1/Th2 cytokines (IL-17, IL-21/IFN-γ/IL-4) in gingival crevicular fluid from 30 chronic periodontitis patients before and after treatment were determined by ELISA. The expression of transcription factors (RORC, T-bet and GATA-3) in peripheral blood was measured by real-time PCR, and the levels of Th17 cells in CD4(+) T cells were determined by flow cytometry. RESULTS: After treatment, the levels of IL-17 and IL-21 were down-regulated (P<0.05), and IL-4 was increased (P<0.05), but there were no differences in the level of IFN-γ (P>0.05). Correspondingly, the expression of RORC was decreased 1.99-fold (P<0.05), and GATA-3 was increased 1.76-fold (P<0.05). However, there were no differences in the level of T-bet (P>0.05). Moreover, the quantity of Th17 cells in peripheral blood was decreased (P<0.05), especially IL-17(+) IFN-γ(+) subgroup. CONCLUSIONS: These results suggest that Th17 cells play a destructive role in the immune balance of periodontitis, and the effect of Th1 cells is not significant, while Th2 cells have a protective effect.

A Classification-Guided Segmentation Algorithm Based on Deep Learning for Epithelium Segmentation in Histopathological Images of Radicular Cysts.

In histopathological analysis of radicular cysts (RCs), lesions in epithelium can provide pathologists with rich information on pathologic degree, which is helpful to determine the type of periapical lesions and make precise treatment planning. Automatic segmentation and localization of epithelium from whole slide images (WSIs) can assist pathologists to complete pathological diagnosis more quickly. However, the class imbalance problem caused by the small proportion of fragmented epithelium in RCs imposes challenge on the typical automatic one-stage segmentation method. In this paper, we proposed a classification-guided segmentation algorithm (CGSA) for accurate segmentation. Our method was a two-stage model, including a classification network for region of interest (ROI) location and a segmentation network guided by classification. The classification stage eliminated most irrelevant areas and alleviated the class imbalance problem faced by the segmentation model. The results of 5-fold cross validation demonstrated that CGSA outperformed the one-stage segmentation method which was lacking in prior epithelium localization information. The epithelium segmentation achieved an overall Dice's coefficient of 0.722, and intersection over union (IoU) of 0.593, which improved by 5.5% and 5.9% respectively compared with the one-stage segmentation method using UNet.Clinical Relevance- This work presents a framework for automatic epithelium segmentation in histopathological images of RCs. It can be applied to make up for the shortcomings of manual annotation which is labor-intensive, time-consuming and objective.

RETRACTED: The effect of combined application of pentoxifylline and vitamin E for the treatment of osteoradionecrosis of the jaws: a meta-analysis.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the corresponding author and following a translated comparative examination of the two articles for similarity. It has been concluded that duplicate publication has occurred. The significantly duplicated article of the same title by same research team is: The effect of combined application of pentoxifylline and vitamin E for the treatment of osteoradionecrosis of the jaws: A meta-analysis Chin J Stomatol Res (Electronic Edition). August 2017, Vol.11, No.4. Both articles report on a meta-analysis study and focus on the treatment of osteoradionecrosis of the jaws by pentoxifylline combined with vitamin E, with search timeframe extending 2 years later in the retracted article.

[Advances in the study of tumor pH-responsive polymeric micelles for cancer drug targeting delivery].

This review presents the state of the art of pH-responsive polymeric micelles for cancer drug delivery. Solid tumors have a weakly acidic extracellular pH (pH < 7), and cancer cells have even more acidic pH in endosomes and lysosomes (pH 4-6). The pH-gradients in tumor can be explored for tumor targeting and drug release in cancer drug delivery by applying pH-responsive polymeric micelles. The pH-responsive polymeric micelles consist of a corona and a core, and are made of amphiphilic copolymers, in which there are pH-responsive polymeric blocks. Two types of pH-responsive polymers-protonizable polymers and acid-labile polymers have been mainly used to make pH-responsive micelles for drug delivery. The protonizable polymers are polybases or polyacids, and their water-soluble/insoluble or charge states undergo changes with the protonation or deprotonation stimulated by external acidity, while the acid-labile polymers change their physical properties by chemical reaction stimulated by the acidity. Polymeric micelles whose core or coronas respond to the tumor extracellular acidity can be explored for triggering the fast release of the carried drug, activating the targeting group and accelerating the endocytosis of drug-loaded polymeric micelles, and those whose core or coronas respond to the tumor lysosomal acidity can be used for facilitating their escape from the lysosomes and targeting the nucleus. Various in vivo and in vitro experiments demonstrated that pH-responsive polymeric micelles are effective for cellular targeting, internalization, fast drug release and nuclear localization, and hence enhancing the therapeutic efficacy and reducing the side effect of cancer chemical therapy.

[Platinum tetrachloride coupled PEG-PEI as drug carrier and gene delivery vector].

OBJECTIVE: To construct a drug carrier and gene vector PEG-PEI-Pt. METHODS: Polyethyleneglycol (PEG) was coupled to polyethylenimine (PEI 600) and platinum tetrachloride; PEG-PEI-Pt complex was formed in ethanol. The complex was characterized by XRD, UV-VIS and FT-IR and the DNA condensation was tested by electrophoretic mobility shift assay. The cell viability was evaluated by MTT assay in Hela, B16, A293 and COS-7 cells and in vitro transfection efficiency was measured in A293 and B16 cells. RESULT: The structure of PEG-PEI-Pt was characterized by XRD, UV-VIS and FT-IR. PEG-PEI-Pt complex was able to bind DNA at N/P weight ratio of 0.4:1; the complex showed cytotoxicity on Hela and B16 cells. The complex had higher transfection efficiency in A293 and B16 cells than PEI 600. CONCLUSION: A novel drug carrier and gene vector PEG-PEI-Pt was constructed successfully.

Effects of mechanical force application on the developing root apex in rat maxillary molars.

OBJECTIVES: We aimed to investigate the effects of mechanical force application on the developing root apex in vivo. DESIGN: Mechanical force was applied on the maxillary first molars of Sprague-Dawley rats at postnatal day 21 for 1, 3, 5, and 7 days to induce tooth movement. We observed the developing root apex of the mesial root of first molar by using micro-focus X-ray computed tomography, histological staining, immunohistochemistry and in situ hybridization to analyze apical cell proliferation and gene expression. Moreover, the force was released after 3 and 7 days of tooth movement, and root apical morphology at postnatal day 35 was subsequently observed. RESULTS: After 1 and 3 days of tooth movement, root apical morphology was altered by increasing immune-reactivity of laminin in the forming periodontal ligament. After 7 days of tooth movement, the root length decreased significantly with bending root apex, decreased cell proliferation and altered gene expression in developing root apex. At postnatal day 35, apical morphology showed no obvious abnormality when the force was released after 3 days of tooth movement, whereas root apical bending was not rescued when the force was released after 7 days. CONCLUSIONS: Relatively short-term force application had no obvious adverse effects on the developing root apex. However, relatively long-term force application altered root apex by affecting Hertwig's epithelial root sheath morphology and apical cellular behavior.

Effects of articular disc or condylar cartilage resection on mandibular growth in young rats.

OBJECTIVE: This study was aimed to compare the effects of articular disc and condylar cartilage resection on mandibular growth in Sprague Dawley rats. DESIGN: Eighty-four male Sprague Dawley rats (age = 4 weeks) were grouped according to the following procedures: group A (n = 21), exclusive surgical exposure of articular disc and condylar cartilage; group B (n = 21), exclusive surgical resection of articular disc; group C (n = 21), exclusive surgical resection of condylar cartilage; group D (n = 21), surgical resection of both articular disc and condylar cartilage. All surgery was performed in unilateral. One rat was killed in each group immediately after the surgery. Hematoxylin and eosin (H&E) staining was used to confirm the completely removal of the disc or cartilage. Five rats in the four groups were sacrificed in 1, 3, 6, and 9 weeks post-operation. The heights and lengths of the mandibles were measured and analyzed statistically. RESULTS: The mandibular height of group D (5.01 ± 0.25 mm) was statistically lower than group A (5.59 ± 0.17 mm) at 1 week post-operation. The height of group C (5.62 ± 0.26 mm) was significantly lower than group A (6.27 ± 0.31 mm) 3 weeks after surgery. The height of group B (6.38 ± 0.36 mm) was significantly lower than group A (6.95 ± 0.10 mm) 6 weeks after surgery. At 9 weeks post-operation, the mandibular heights in groups B, C, and D were lower than group A, group D was lower than group C, and group C was lower than group B. The lengths of the mandibles were not significantly decreased until 9 weeks post-operation in group D. CONCLUSIONS: The increase in mandibular height was interfered after either articular disc or condylar cartilage was resected, and mandibular height deficiency likely occurred earlier and more severely when cartilage was resected. However, the increase in mandibular length was barely interfered when either articular disc or condylar cartilage was resected.

Adipose-derived stem cells prevent the onset of bisphosphonate-related osteonecrosis of the jaw through transforming growth factor ß-1-mediated gingival wound healing.

BACKGROUND: Due to its complex pathogenesis and low clinical cure rate, bisphosphonate-related osteonecrosis of the jaw (BRONJ) poses a substantial challenge for oral and maxillofacial surgeons. Therefore, the treatment of BRONJ should focus on prevention. In clinical studies, primary wound closure can significantly reduce the incidence of BRONJ. Whether local stem cell transplantation can promote primary gingival healing in patients with a medication history and prevent BRONJ has not been reported. METHODS: In this study, animals were divided into a healthy group (non-drug treatment), a BP group, a hydroxyapatite (HA) group, and an adipose-derived stem cell (ADSC) group. All groups except the healthy group were treated with BPs and immunosuppressive drugs once per week for 8 weeks, simulating clinical use for the treatment of cancer patients with bone metastasis, to induce BRONJ-like animals. After the sixth drug treatment, the bilateral premolars were extracted in all groups. In contrast to the healthy and BP groups, the extraction sockets in the HA and ADSC groups were filled with HA or HA + ADSCs simultaneously post extraction to observe the preventive effect of ADSCs on the occurrence of BRONJ. At 2 and 8 weeks post extraction, animals from all groups were sacrificed. RESULTS: At 8 weeks post transplantation, ADSCs prevented the occurrence of BRONJ, mainly through accelerating healing of the gingival epithelium at 2 weeks post extraction. We also found that ADSCs could upregulate the expression of transforming growth factor ß1 (TGF-ß1) and fibronectin in tissue from animals with a medication history by accelerating gingival healing of the extraction socket. A rescue assay further demonstrated that TGF-ß1 and fibronectin expression decreased in TGF-ß1-deficient ADSC-treated animals, which partially abolished the preventive effect of ADSCs on the onset of BRONJ. CONCLUSION: ADSCs prevent the onset of BRONJ, mainly by upregulating the expression of TGF-ß1 and fibronectin to promote primary gingival healing, ultimately leading to bone regeneration in the tooth extraction socket. Our new findings provide a novel stem cell treatment for the prevention of BRONJ.