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Zirconia is widely used in the field of dentistry because of its superior mechanical and esthetic characteristics. However, the tetragonal zirconia polycrystal restorations commonly used in clinics will degrade at low temperatures in the oral environment, resulting in increased surface roughness, microcracks, and decreased mechanical properties. Low-temperature degradation of zirconia can be affected by grain size, stress, stabilizer content and type, surface treatment, sintering conditions, and other factors. Through a literature review and analysis, this review summarizes the research progress on the low-temperature degradation of zirconia in prosthetic dentistry to provide references for the improvement of zirconia in clinical and research applications.
Subject(s)
Ceramics , Dental Materials , Esthetics, Dental , Materials Testing , Prosthodontics , Surface Properties , Temperature , Yttrium/chemistry , ZirconiumABSTRACT
OBJECTIVE@#To analyze the marginal roughness and marginal fitness of chairside computer-aided design and computer-aided manufacturing (CAD/CAM) laminate veneers with different materials and thicknesses, and to provide a reference for the clinical application of laminate veneers.@*METHODS@#The butt-to-butt type laminate veneers were prepared on resin typodonts, the preparations were scanned, and the laminate veneers were manufactured by chairside CAD/CAM equipment. The laminate veneers were divided into four groups (n=9) according to the materials (glass-matrix ceramics and resin-matrix ceramics) and thickness (0.3 mm and 0.5 mm) of the veneers, with a total of 36. The marginal topo-graphies of each laminate veneer were digitally recorded by stereomicroscope, and the marginal rough-nesses of the laminate veneers were determined by ImageJ software. The marginal fitness of the laminate veneers was measured by a fit checker and digital scanning and measuring method. At the same time, the mechanical properties of glass-matrix ceramic and resin-matrix ceramic bars (n=20) were tested by a universal testing device.@*RESULTS@#The marginal roughness of 0.3 mm and 0.5 mm glass-matrix ceramic laminate veneers was (24.48±5.55) μm and (19.06±5.75) μm, respectively, with a statistically significant difference (P < 0.001). The marginal roughness of 0.3 mm and 0.5 mm resin-matrix ceramic laminate veneers was (6.13±1.27) μm and (6.84±2.19) μm, respectively, without a statistically significant difference (P>0.05). The marginal roughness of the glass-matrix ceramic laminate veneers was higher than that of the resin-matrix ceramic laminate veneers with a statistically significant difference (P < 0.001). The marginal fitness of 0.3 mm and 0.5 mm glass-matrix ceramic laminate veneers were (66.30±26.71) μm and (85.48±30.44) μm, respectively. The marginal fitness of 0.3 mm and 0.5 mm resin-matrix ceramic laminate veneers were (56.42±19.27) μm and (58.36±8.33) μm, respectively. There was no statistically significant difference among the 4 groups (P>0.05). For glass-matrix ceramics, the flexural strength was (327.40±54.25) MPa, the flexural modulus was (44.40±4.39) GPa, and the modulus of resilience was (1.24±0.37) MPa. For resin-matrix ceramics, the flexural strength was (173.71±16.61) MPa, the flexural modulus was (11.88±0.51) GPa, and the modulus of resilience was (1.29±0.27) MPa. The flexural strength and modulus of glass-matrix ceramics were significantly higher than those of resin-matrix ceramics (P < 0.001), but there was no statistically significant difference in the modulus of resilience between the two materials (P>0.05).@*CONCLUSION@#The marginal roughness of CAD/CAM glass-matrix ceramic laminate veneers is greater than that of resin-matrix ceramic laminate veneers, but there was no statistically significant difference in marginal fitness among them. Increasing the thickness can reduce the marginal roughness of glass-matrix ceramic laminate veneers, but has no effect on the marginal roughness of resin-matrix ceramic laminate veneers.
Subject(s)
Ceramics , Computer-Aided Design , Dental Porcelain , Dental Veneers , Materials Testing , Surface PropertiesABSTRACT
Background/Aims@#Cigarette smoking is an important modifiable risk factor in kidney disease progression. However, the underlying mechanisms for this are lacking. This study aimed to assess whether nicotine (NIC), a major toxic component of cigarette smoking, would exacerbates tacrolimus (TAC)-induced renal injury. @*Methods@#Sprague-Dawley rats were treated daily with NIC, TAC, or both drugs for 4 weeks. The influence of NIC on TAC-caused renal injury was examined via renal function, histopathology, oxidative stress, mitochondria, endoplasmic reticulum (ER) stress, and programmed cell death (apoptosis and autophagy). @*Results@#Both NIC and TAC significantly impaired renal function and histopathology, while combined NIC and TAC treatment aggravated these parameters beyond the effects of either alone. Increased oxidative stress, ER stress, mitochondrial dysfunction, proinf lammatory and profibrotic cytokine expressions, and programmed cell death from either NIC or TAC were also aggravated by the two combined. @*Conclusions@#Our observations suggest that NIC exacerbates chronic TAC nephrotoxicity, implying that smoking cessation may be beneficial for transplant smokers taking TAC.
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Background/Aims@#Accumulating evidence indicates that L-carnitine (LC) protects against multiorgan damage through its antioxidant properties and preservation of the mitochondria. Little information is available about the effects of LC on renal fibrosis. This study examined whether LC treatment would provide renoprotection in a rat model of unilateral ureteral obstruction (UUO) and in vitro. @*Methods@#Sprague-Dawley rats that underwent UUO were treated daily with LC for 7 or 14 days. The influence of LC on renal injury caused by UUO was evaluated by histopathology, and analysis of gene expression, oxidative stress, mitochondrial function, programmed cell death, and phosphatidylinositol 3-kinase (PI3K)/ AKT/forkhead box protein O 1a (FoxO1a) signaling. In addition, H2O2-exposed human kidney cells (HK-2) were treated with LC. @*Results@#LC treatment inhibited expression of proinflammatory and profibrotic cytokines, and was followed by a significant attenuation of tubulointerstitial inflammation and fibrosis. The increased oxidative stress caused by UUO was associated with mitochondrial dysfunction and excessive apoptosis and autophagy via PI3K/AKT/FoxO1a-dependent signaling, and this was abrogated by administration of LC. In H2O2-exposed HK-2 cells, LC decreased intracellular production of reactive oxygen species, and suppressed expression of profibrotic cytokines and reduced the number of apoptotic cells. @*Conclusions@#LC protects against the progression of tubulointerstitial fibrosis in an obstructed kidney.
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BACKGROUND/AIMS@#Evidence suggests that Shen-Kang (SK), a traditional Chinese herbal medicine, protects against various types of renal injury. In this study, we evaluated whether SK treatment confers renoprotection in a rat model of chronic tacrolimus (TAC) nephropathy.@*METHODS@#Rats were treated daily with TAC (1.5mg/kg, subcutaneously) and SK (450 mg/kg, intravenously) for 4 weeks. The effects of SK on TAC-induced renal injury were assessed by measuring renal function, urine albumin excretion, histopathology, inflammatory cell infiltration, expression of profibrotic (transforming growth factor β1 [TGF-β1] and TGF-β inducible gene-h3 [βig-h3]) and proinflammatory cytokines, oxidative stress, and apoptotic cell death.@*RESULTS@#Administration of SK preserved glomerular integrity (fractional mesangial area and Wilms tumor 1-positive glomeruli), attenuated tubulointerstitial fibrosis, and reduced the number of ectodermal dysplasia 1-positive cells, and this was paralleled by improved urine albumin excretion and renal dysfunction. At the molecular level, SK treatment suppressed expression of TGF-β1/Smad2/3, βig-h3, and proinflammatory cytokines. Oxidative stress and apoptotic cell death were significantly decreased with SK treatment, and apoptosis-related genes were regulated toward cell survival (active caspase-3 and the B-cell lymphoma-2/Bcl2-associated X [Bcl-2/Bax] ratio).@*CONCLUSIONS@#SK protects against TAC-induced renal injury.
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BACKGROUND: Proximal humeral fracture is a common disease of fall injury in the elderly, because of bone nonunion after treatment with a variety of factors such as senile osteoporosis. Currently, the use of reverse total shoulder arthroplasty has achieved good clinical effect, but has certain limitations. OBJECTIVE: To compare and observe the clinical effects of reverse total shoulder arthroplasty and open reduction and internal plate fixation in the treatment of nonunion of proximal humeral fractures. METHODS: Totally 120 cases of nonunion of proximal humeral fractures were randomly divided into observation group and control group, with 60 cases in each group. The observation group received reverse total shoulder arthroplasty (replacement of artificial shoulder joint). The control group received open reduction and internal plate fixation. RESULTS AND CONCLUSION: (1) Follow-up results: At 3 years after surgery, the pain score was lower in the observation group than that in the control group (P < 0.05). Constant daily activities, range of activities, strength test score, Constant total score, satisfaction and hospitalization expenses were higher in the observation group than in the control group. Functions of flexion, laterotorsion and intorsion were better in the observation group than those in the control group (P < 0.05). (2) Adverse reactions: At 3 years after surgery, 26 and 22 cases had adverse reaction in the observation group and the control group respectively. (3) The results show that the clinical effect of the elders' nonunion of proximal humeral fracture treated with reverse total shoulder arthroplasty is quite good, and the pain degree and shoulder function are obviously improved. The curative effect of reverse total shoulder arthroplasty is better than that of open reduction and internal plate fixation.
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Objective To study the regular pattern of inhalational particulate matter deposition in respiratory tract and its influencing factors during breathing by numerical simulation method. Methods Three-dimensional finite element model of normal human respiratory tract was established to simulate the airflow distributions in respiratory tract during inspiration. The particles were released at the entrance of nose or mouth to simulate the deposition process of suspended particles by inhaled airflow in respiratory tract. Different parameters such as particle diameter, particle density and flow rate of air volume were used for comparative analysis to investigate their functions as influencing factors when particle deposition happened in respiratory tract. Results The particles were mainly deposited in nasal threshold, nasal middle airway, nasopharynx, and bronchial inner wall of respiratory tract. The particle deposition rate increased with the parameters of particle diameter, particle density and air volume flow rate increasing. The influence of different parameters on the deposition rate was not the same. Conclusions The particle is mainly deposited at the site with complex geometry or at the position where path direction changes violently. Particle diameter, density and breathing airflow rate will affect the deposition rate in respiratory tract. These research findings will provide numerical references for the clinical assessment on risk of respiratory diseases caused by air pollution.
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Despite strict pre- and post-transplantation screening, the incidence of new-onset diabetes after transplantation (NODAT) remains as high as 60%. This complication affects the risk of cardiovascular events and patient and graft survival rates. Thus, reducing the impact of NODAT could improve overall transplant success. The pathogenesis of NODAT is multifactorial, and both modifiable and nonmodifiable risk factors have been implicated. Monitoring and controlling the blood glucose profile, implementing multidisciplinary care, performing lifestyle modifications, using a modified immunosuppressive regimen, administering anti-metabolite agents, and taking a conventional antidiabetic approach may diminish the incidence of NODAT. In addition to these preventive strategies, inhibition of dipeptidyl peptidase-4 (DPP4) by the gliptin family of drugs has recently gained considerable interest as therapy for type 2 diabetes mellitus and NODAT. This review focuses on the role of DPP4 inhibitors and discusses recent literature regarding management of NODAT.
Subject(s)
Animals , Humans , Blood Glucose/drug effects , Diabetes Mellitus/diagnosis , Dipeptidyl Peptidase 4/metabolism , Dipeptidyl-Peptidase IV Inhibitors/therapeutic use , Organ Transplantation/adverse effects , Risk Assessment , Risk Factors , Treatment OutcomeABSTRACT
This study examined the osteogenic effect of electromagnetic fields (EMF) under the simulated in vivo conditions. Rat bone marrow mesenchymal stem cells (BMSCs) and rat osteoblasts were co-cultured and exposed to 50 Hz, 1.0 mT EMF for different terms. Unexposed single-cultured BMSCs and osteoblasts were set as controls. Cell proliferation features of single-cultured BMSCs and osteoblasts were studied by using a cell counting kit (CCK-8). For the co-culture system, cells in each group were randomly chosen for alkaline phosphatase (ALP) staining on the day 7. When EMF exposure lasted for 14 days, dishes in each group were randomly chosen for total RNA extraction and von Kossa staining. The mRNA expression of osteogenic markers was detected by using real-time PCR. Our study showed that short-term EMF exposure (2 h/day) could obviously promote proliferation of BMSCs and osteoblasts, while long-term EMF (8 h/day) could promote osteogenic differentiation significantly under co-cultured conditions. Under EMF exposure, osteogenesis-related mRNA expression changed obviously in co-cultured and single-cultured cells. It was noteworthy that most osteogenic indices in osteoblasts were increased markedly after co-culture except Bmp2, which was increased gradually when cells were exposed to EMF. Compared to other indices, the expression of Bmp2 in BMSCs was increased sharply in both single-cultured and co-cultured groups when they were exposed to EMF. The mRNA expression of Bmp2 in BMSCs was approximately four times higher in 8-h EMF group than that in the unexposed group. Our results suggest that Bmp2-mediated cellular interaction induced by EMF exposure might play an important role in the osteogenic differentiation of BMSCs.
Subject(s)
Animals , Rats , Alkaline Phosphatase , Bone Marrow Cells , Cell Biology , Radiation Effects , Cell Differentiation , Genetics , Radiation Effects , Cell Proliferation , Radiation Effects , Coculture Techniques , Electromagnetic Fields , Mesenchymal Stem Cells , Radiation Effects , Osteoblasts , Radiation Effects , Osteogenesis , Genetics , Radiation EffectsABSTRACT
This study examined the osteogenic effect of electromagnetic fields (EMF) under the simulated in vivo conditions. Rat bone marrow mesenchymal stem cells (BMSCs) and rat osteoblasts were co-cultured and exposed to 50 Hz, 1.0 mT EMF for different terms. Unexposed single-cultured BMSCs and osteoblasts were set as controls. Cell proliferation features of single-cultured BMSCs and osteoblasts were studied by using a cell counting kit (CCK-8). For the co-culture system, cells in each group were randomly chosen for alkaline phosphatase (ALP) staining on the day 7. When EMF exposure lasted for 14 days, dishes in each group were randomly chosen for total RNA extraction and von Kossa staining. The mRNA expression of osteogenic markers was detected by using real-time PCR. Our study showed that short-term EMF exposure (2 h/day) could obviously promote proliferation of BMSCs and osteoblasts, while long-term EMF (8 h/day) could promote osteogenic differentiation significantly under co-cultured conditions. Under EMF exposure, osteogenesis-related mRNA expression changed obviously in co-cultured and single-cultured cells. It was noteworthy that most osteogenic indices in osteoblasts were increased markedly after co-culture except Bmp2, which was increased gradually when cells were exposed to EMF. Compared to other indices, the expression of Bmp2 in BMSCs was increased sharply in both single-cultured and co-cultured groups when they were exposed to EMF. The mRNA expression of Bmp2 in BMSCs was approximately four times higher in 8-h EMF group than that in the unexposed group. Our results suggest that Bmp2-mediated cellular interaction induced by EMF exposure might play an important role in the osteogenic differentiation of BMSCs.
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<p><b>OBJECTIVE</b>To explore the effect of septoplasty or in combination with out fracture of the inferior turbinate in patients with nasal septum deviation on the airflow field and the nasal airway structure.</p><p><b>METHODS</b>Six patients with nasal septum deviation underwent spiral CT imaging scans before surgery and during the follow-up. The 3D finite element meshes of the nasal airway were developed from the above CT scans. Given three preconditions, the nasal airflow fields were described by the Navier-Stokes and continuity equations at the inspiratory flow rate of 12 L/min. The whole airflow patterns were obtained and then compared with the airflow filed and airway structure changes before and after surgery. SPSS 12.0 software was used to analyze the data.</p><p><b>RESULTS</b>Before surgery, area of the common airway and the middle and ventral medial regions in the concave side were (1.61 ± 0.18), (0.40 ± 0.10), (0.40 ± 0.14) cm(2) respectively, and those of convex side were (1.30 ± 0.18), (0.33 ± 0.05), (0.36 ± 0.10) cm(2) respectively. The differences between both sides were of no statistical significance (Z value was 1.782, 1.363, 0.526 respectively, all P > 0.05). Airflow of the above airways were (361 ± 68), (131 ± 25), (100 ± 28) ml respectively in concave side and (178 ± 33), (59 ± 26), (59 ± 18) ml respectively in convex side, which differences were significant statistically (Z value were 2.207, 2.201, 2.201 respectively, all P < 0.05). The inferior turbinate in concave side [(0.93 ± 0.10) cm] was statistically (Z = 2.214, P < 0.05) bigger than that in convex side [(0.58 ± 0.12) cm] before surgery. The airflow fields were in disorder in both ill-airways. After surgery, area of the common airway was (2.55 ± 0.44) cm(2) in concave side and (2.20 ± 0.72) cm(2) in convex side respectively, and area of the middle and ventral medial regions in the convex side were (0.58 ± 0.13), (0.81 ± 0.26) cm(2) respectively, which differences were of significance statistically when comparing to areas before surgery (Z value were 2.201, 2.201, 2.201, 2.201, P < 0.05). The airflow passed through nasal airway orderly in both sides. But the thickness of inferior turbinate was (0.73 ± 0.08) cm in concave side after surgery, which difference was significant statistically in comparison to that before surgery (Z = 2.264, P < 0.05). Consequently, nasal resistance decreased from (0.41 ± 0.03) kPa×L(-1)×s(-1) to (0.16 ± 0.01) kPa×L(-1)×s(-1) after surgery, the difference was significantly (Z = -2.207, P = 0.027).</p><p><b>CONCLUSION</b>Septoplasty or in combination with out fracture of the inferior turbinate, followed by the self-adaptation consecutively, could improve the airway and breathing capacity of the nose.</p>
Subject(s)
Adult , Female , Humans , Male , Young Adult , Air Movements , Nasal Cavity , Physiology , Nasal Obstruction , General Surgery , Nasal Septum , General Surgery , Respiration , Treatment Outcome , Turbinates , General SurgeryABSTRACT
Objective To study the effects of the size and diffraction of tympanic membrane perforation on hearing system of human ear. Method The whole temporal bone from a healthy volunteer is scanned using spiral CT. The digitized outlines of images are imported into ANSYS to construct a three dimensional finite element model of the human ear. ResultsThe resonance frequencies become 3.6, 4.4 and 4.6 kHz with the increase of perforation areas as 0.97, 3.66 and 7.97 mm2, respectively. The larger perforation in the tympanic membrane results in a lower stapes footplate displacement. The displacement swing of the stapes footplate decreased clearly under the action of sound wave from the diffraction. The peak values of the displacement nephogram of the tympanic membrane are 0.32, 0.20 and 0.19 μm at 1000 Hz, respectively. At the resonance frequency, the peak values of the displacement nephogram of the tympanic membrane are 0.20, 0.14 and 0.09 μm, respectively. Conclusions The larger the size of the perforation is, the smaller stapes footplate displacement will be, especially at the lower frequency of 4 kHz with the higher resonance frequency. The peak values of displacement nephogram will become smaller with the increased size of perforations. The results would give helpful information for the clinical treatment.
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Objective To investigate the influence of airway structural changes after reconstruction of nasal cavity structure on the airflow patterns within the whole upper airway and the movement of soft palate in patient with OSAHS accompanied by nasal abnormality. Method Based on the preoperative and postoperative CT data from the patient with OSAHS, the three dimensional finite element model of the upper airway and the soft palate were reconstructed. The preoperative and postoperative flow characteristics of the upper airway and movement of the soft palate were simulated by the fluid solid interaction method. Results The surgical operation altered the abnormal anatomy of the nasal cavity. The nasal airway resistance and the whole upper airway resistance decreased significantly. Meanwhile, it was shown that the soft palate edema remitted obviously, and the motion amplitude of the free edge also decreased. The displacement of the soft palate increased with the decrease in elastic modulus of soft palate. Postoperative numerical results showed a good agreement with the experimental and computational results of the normal human in literature review. Conclusions The reconstruction of the nasal cavity structure influenced the airflow patterns and the movement of soft palate through altering the anatomy of the upper airway. The movement of soft palate was affected by the variations of elastic modulus under different pathophysiologic conditions.
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<p><b>OBJECTIVE</b>To determine the outcome of anatomically corrective repair and traditional repair of corrected transposition of great arteries (c-TGA) with heart anomaly.</p><p><b>METHODS</b>From April 2002 to December 2006, nineteen patients including fourteen male and five female with c-TGA, underwent operations, age ranged from 2 to 22 years old and weight ranged from 10 to 48 kg. Fifteen of them received anatomically corrective repair and the other four received traditional repair. Eighteen patients were referred to SLL (segmental anatomy) in situs solitus while fifteen of them with levocardia and three with dextrocardia. One patient was referred to IDD (segmental anatomy) in situs inversus with levocardia. Associated cardiac lesions included ventricular defect in eighteen patients, double outlet of right ventricle in one patient, pulmonary stenosis in seventeen patients and pulmonary hypertension in two patients. The operative procedures to anatomically correct atrioventricular discordance included an atrial switch plus a ventricle-arterial switch. The atrial switch was performed using the modified Senning procedure (n=13), Senning procedure (n=1) and Mustard procedure (n=1). The ventricle-arterial switch was performed using a Rastelli procedure (n=13) or an arterial switch (n=2). The patients underwent Mustard and Rastelli procedure had received bi-direct Gleen shunt due to postoperative high pressure of superior vena cava. Three patients underwent traditional cardiac repair because of small ventricular septal defect and one patient was reoperated to undergo traditional cardiac repair because of left ventricular failure after received anatomically corrective repair.</p><p><b>RESULTS</b>In the patients received anatomically corrective repair, there was one early operative death received a modified Senning atrial switch and an arterial switch. The cause of death was acute myocardial failure due to imperfect coronary transfer. The postoperative complications included severe low cardiac output syndrome (n=1), temporary atrioventricular block (n=1) and thorax cavity fluidify (n=1). The survivors were followed up for 6 months to 4 years. All were sinus cardiac rhythm and in NYHA class I or II. There was no death in the patients received traditional repair. Four patients were followed up for 1 year. Three patients were in NYHA I or II class and one patient in class II.</p><p><b>CONCLUSIONS</b>Anatomically corrective repair of c-TGA can be performed with good operative survival and intermediate-term outcome. The patients with good right ventricular function and well developed tricuspid valve who were difficult to undergo anatomically corrective repair might be fit to receive traditional repair.</p>
Subject(s)
Adolescent , Adult , Child , Child, Preschool , Female , Humans , Male , Cardiac Surgical Procedures , Methods , Follow-Up Studies , Heart Defects, Congenital , General Surgery , Transposition of Great Vessels , General Surgery , Treatment OutcomeABSTRACT
BACKGOUND: Dendritic cells (DC) are pivotal antigen presenting cells and serve a unique role in initiating immunity. To test the hypothesis that pre-immunization of recipient with certain DC subsets of donor origin can influence graft outcome. METHODS: We have studied the effects of immunization with allogeneic CD4+CD11c+(MDC) and CD8+CD11c+(LDC) DCs on the allograft response. RESULTS: Both immature MDC and LDC subsets from DBA/2 were able to prime naive allogeneic C57BL/6 (B6) T cells in MLR. In vitro allogeneic T cell responses were attenuated by the addition of anti-CD154 mAb into the culture. T cells from B6 mice that received DBA/2 MDC intravenously 4 weeks before testing mounted weaker MLR driven cell proliferation than T cells from LDC pretreated B6 mice. Consistent with the MLR results, combined pretreatment with MDC, but not LDC, plus anti-CD154 mAb produced donor-strain specific long-term graft survival and induced tolerance while treatment with LDC plus anti-CD154 mAb created minimal prolongation of allograft survival in a pancreas islet transplant model (DBA/2->B6). The beneficial effects exerted by MDC and anti-CD154 mAb pretreatment were correlated with TH1 to TH2 immune deviation and with the amplified donor-specific suppressive capacity by recipient CD4+CD25+T cells. CONCLUSION: These findings highlight the capacity of MDC to modulate alloimmune responses, and suggest therapeutic approaches for the induction of donor specific tolerance.