H-type blood vessels participate in alveolar bone remodeling during murine tooth extraction healing.

OBJECTIVES: We aimed to investigate whether skeletal-specific H-type blood vessels exist in alveolar bone and how they function in alveolar bone remodeling. MATERIALS AND METHODS: H-type vessels with high expression of CD31 and Endomucin (CD31hi Emcnhi ) were immunostained in alveolar bone. Abundance and age-related changes in CD31hi Emcnhi endothelial cells (H-ECs) were detected by flow cytometry. Osteoprogenitors association with H-type vessels and bone mass were detected in tooth extraction model of alveolar bone remodeling by immunohistofluorescence and micro-CT, respectively. Transcription and expression of H-EC feature genes during in vitro Notch inhibition were measured by RT-qPCR and immunocytofluorescence. RESULTS: We verified that H-type vessels existed in alveolar bone, the abundance of which was highest at infancy age, then decreased but maintained a constant level during aging. In tooth extraction model, H-ECs significantly increased with concomitant perivascular accumulation of Runx2+ osteoprogenitors and gradually augmentation of bone mass. Notch inhibition of in vitro cultured H-ECs resulted in decreased expression levels of Emcn and hes1, but not Pecam1 or Kdr genes, with decreased expression levels of H-EC numbers, accordingly. CONCLUSIONS: The present study suggests that H-type vessels promote osteogenesis during alveolar bone remodeling. Notch signaling pathway regulates expression of Emcn and possibly determines fate and functions of alveolar H-ECs.

[Three-dimensional finite element analysis of cuspal-coverage thickness influence on the stress distribution of all-ceramic onlay-restored premolars].

OBJECTIVE: To investigate the influence of cuspal-coverage thickness on the stress distribution of all-ceramic onlay-restored premolars by using 3D finite element (FE) analysis and to provide references for the design of all-ceramic onlays for clinical application. METHODS: 3D FE models of all-ceramic onlays with three cuspal-coverage thicknesses (2, 3, and 4 mm) of endodontically treated maxillary premolar were constructed based on micro-CT images. Stress distributions in the onlay, adhesive resin cement layer, and dentin of models were analyzed under vertical load (600 N) and oblique load (200 N). RESULTS: When the cuspal-coverage thickness increased, the peak maximum principal stress value decreased inside the onlay but increased in the margin of the adhesive resin cement layer. In addition, stress concentration areas increased in the coronal residual dentin on the palatal side under oblique load. CONCLUSIONS: An increase in the cuspal-coverage thickness of all-ceramic onlays may reduce the risk of rupture of the restoration but may deteriorate the restoration and cause palatal dentin fracture.

[Effects of three drying methods on the physical properties and drug delivery in chitosan microspheres].

OBJECTIVE: The purpose of this study is to investigate the effects of different drying methods on the physical properties and drug delivery of chitosan microspheres. METHODS: Three types of drying methods were utilized, including air drying and freeze drying after freezing at -20 ℃ (slow cooling) and at -80 ℃ (fast cooling). The physical properties of microspheres were characterized. Utilizing bovine serum albumin (BSA) as the model drug, the in-vitro release behaviors of drug-loaded beads were investigated. RESULTS: By comparing the physical properties of the different drying methods, the microspheres' diameters, porosities, and surface area were observed to increase successively from air drying and slow cooling to fast cooling, whereas the pore size and the swelling and degradation rates varied. The drug-loading experiments revealed that the loading capacity of air-dried microspheres was the lowest and the release rate was the slowest. Although the loading capacity of fast cooling microspheres was high, an obvious burst release was observed. The loading capacity of slow cooling microspheres was similar to that of the fast cooling microspheres and the loaded BSA can be released continuously. CONCLUSIONS: The results indicate that different drying methods can affect the physical properties of chitosan microspheres, which further influence drug loading and release.

[Research advances in endogenous neural stem cells promoting neural repair after ischemic stroke].

Neural stem cell therapy, as a new therapeutic method for neural diseases, has aroused a wide concern for over 20 years since neural stem cells were first found in 1992. Ischemic stroke is highly concerned because of its high incidence, mortality and disability rates. Because the brain has a limited ability to repair itself, to improve neural function and promote neural regeneration may help to prevent occurrence and development of neurological diseases. It is noteworthy that some stroke patients showed an ability to repair brain several months after the stroke happened, suggesting an existence of endogenous nerve repair in these patients. The research advances in functions of endogenous neural stem cells in neural regeneration and the related regulators after ischemic stroke are summarized in this review to provide new views of the mechanism of neural functional recovery after ischemic stroke.

Autophagy mediates oral submucous fibrosis.

Oral submucous fibrosis (OSF) is a chronic insidious disease of the oral mucosa, well-recognized as a premalignant condition and commonly found in Southern China. It is primarily caused by the habit of areca nut or gutkha chewing. OSF is believed to be a homeostatic disorder of the extracellular matrix and fibroblast proliferation. The present study demonstrated a novel link between autophagy and OSF. Tissue samples from human OSF showed an overexpression of the autophagy marker microtubule-associated protein 1 light chain 3 using immunohistochemistry and quantitative polymerase chain reaction. With regard to the crucial role of transforming growth factor (TGF)-ß in OSF disease, western blot analysis demonstrated that TGF-ß signaling was shown to contribute to the activation of autophagy in fibroblasts in vitro; however, a cell apoptosis and MTS assay demonstrated that the suppression of autophagy ameliorated the fibrosis induced by active TGF-ß receptor type I signaling, as well as promoted fibroblast apoptosis and suppressed proliferation. Therefore, the present results suggest that autophagy serves a crucial function in OSF.

[Construction of tissue engineered gingiva with gingival epithelia and acellular dermal matrix].

OBJECTIVE: To culture human gingival epithelia in vitro, and to construct the tissue engineered gingiva with the acellular dermal matrix (ADM). METHODS: Human gingival epithelia were isolated from the gingival tissue, and the cells were cultured and seeded onto the surface of ADM. After 7 days of submerged incubation, an air-liquid interface culture was performed for 7, 14, and 21 days. The complex constructed above was taken for histological examination. RESULTS: Human gingival epithelia could proliferate well on the surface of ADM, and form multilayer structure. But the superficial epithelium was partially keratinized. CONCLUSION: Tissue engineered gingiva may be constructed with human gingival epithelia and ADM in vitro.

[Effects of Porphyromonas gingivalis lipopolysaccharide on collagen phagocytosis by human periodontal ligament fibroblasts].

OBJECTIVE: To investigate the effects of Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) on collagen phagocytosis of human periodontal ligament fibroblasts (hPDLF). METHODS: Fluorescence localization and flow cytometry was used to test the collagen phygocytosis of hPDLF stimulated by the various concentration of LPS for 48 hours in vitro. RESULTS: The collagen phygocytosis of hPDLF was increased significantly by 0.1 microg/mL LPS (P < 0.05). CONCLUSION: This study indicates that P. gingivalis LPS may enhance the degradation of collagen by stimulating the phagocytic activity of the hPDLF in periodontitis.

[Rat dental papilla cell culture with nanometer-HAP in vitro].

OBJECTIVE: To determine the effects of nano-hydroxyapatite(nano-HAP)on the proliferation and activity of rat dental papilla cells(RDPCs)in vitro, and to evaluate the feasibility of using nano-hydroxyapatite(nano-HAP)as dental papilla cell scaffold in dental tissue engineering. METHODS: RDPCs cultured with the porous nano-HAP in vitro served as the experimental group, and the routine culture of RDPCs in flasks served as the control. Scanning electronic microscope was used to observe the growth and adherence of the RDPCs to nano-HAP. Cell proliferation, cellular protein content, and alkaline phosphatase(ALP) were detected to assess the cellular activities. RESULTS: RDPCs proliferated well, and adhered to the outer and inner surface of the nano-HAP scaffold. Compared with the control group, cells in the experimental group presented higher proliferation on 6 d and 8 d and higher cellular protein content on 6 d and 9 d. No significant difference was detected in the ALP activity in the 2 groups. CONCLUSION: RDPCs seeded into nano-HAP grow better and have more vigorous cellular activity, suggesting that nano-HAP has excellent biocompatibility with dental papilla cells, and it can serve as a promising scaffold for dental tissue engineering.

[Effect of porcelain firing cycle on microstructure and corrosion resistance of 4 metal ceramic alloys].

OBJECTIVE: To determine the effect of porcelain firing cycle on microstructure of 4 metal ceramic alloys, and to analyze the changes of their corrosion resistance in the artificial saliva. METHODS: We simulated the process of firing and repolishing when fabricating porcelain-fused-to-metal restoration in clinic,and then observed the microstructures of Ni-Cr, Ni-Cr-Ti, Co-Cr alloys and high gold alloy by field emission scanning electron microscopy and energy dispersive spectroscopy. The electrochemical corrosion behavior of alloys in artificial saliva was analyzed by polarization curves and corrview 2 corrosion analysis software. The data of self-corrosion potential and transpassive potential were obtained and analyzed. RESULTS: After the porcelain firing cycle, the surface composition changed slightly, and the morphological in the 3 predominate base metal alloys also changed. The self-corrosion potential turned to more negative, and the transpassive potential declined. CONCLUSION: The procedure of porcelain firing cycle can affect the surface microstructure and increase the corrosion of 4 metal-ceramic alloys.

[Garlicin and formocresol in the treatment of chronic periapical periodontitis].

OBJECTIVE: To evaluate the short period clinical responses after sealed garlicin and formocresol small cotton ball in the root canal entrance to treat chronic periapical periodontitis. METHODS: Treatment records of 185 teeth with chronic periapical periodontitis were compared. Of them, 94 teeth were treated by sealed small garlicin cotton ball in the root canal entrance, 78 were treated by sealed small formocresol cotton ball in the root canal entrance, and the other 13 were treated by sealed small normal saline cotton ball. The curative effects were evaluated through clinical observation. RESULTS: The ratios of acute reaction in 3 days following sealed garlicin, formocresol and normal saline small cotton ball were 5.1%, 10.7%, and 50% in the anterior teeth, and 5.5%, 8.0%, and 60%, in the posterior teeth, respectively. CONCLUSION: The clinical curative effects were similar between garlicin and formocresol in the short period. Formocresol can be substituted by garlicin.