Protective Effects of 18ß-Glycyrrhetinic Acid on Neonatal Rats with Hyperoxia Exposure.

Bronchopulmonary dysplasia (BPD) is a common devastating pulmonary complication in preterm infants. Supplemental oxygen is a lifesaving therapeutic measure used for premature infants with pulmonary insufficiency. However, oxygen toxicity is a significant trigger for BPD. Oxidative stress disrupts lung development, accompanied by increased pro-inflammatory cytokines and chemokines expression and immune cells infiltration in lung tissue. Licorice, a typical traditional herbal medicine, is commonly used in the medicine and food industries. 18ß-Glycyrrhetinic acid (18ß-GA), a primary active ingredient of licorice, has powerful anti-oxidative and anti-inflammatory effects. This study aimed to determine whether 18ß-GA has a protective effect on neonatal rats with hyperoxia exposure. Newborn Sprague-Dawley rats were kept in either 21% (normoxia) or 80% O2 (hyperoxia) continuously from postnatal day (PN) 1 to 14. 18ß-GA was injected intragastrically at 50 or 100 mg/kg body weight once a day from PN 1 to 14. We examined the body weight and alveolar development and measured ROS level and the markers of pulmonary inflammation. Mature-IL-1ß and NF-κB pathway proteins, and the NLRP3 inflammasome, were assessed; concurrently, caspase-1 activity was measured. Our results indicated that hyperoxia resulted in alveolar simplification and decreased bodyweight of neonatal rats. Hyperoxia increased ROS level and pulmonary inflammation and activated NF-κB and the NLRP3 inflammasome. 18ß-GA treatment inhibited the activation of NF-κB and the NLRP3 inflammasome, decreased ROS level and pulmonary inflammation, improved alveolar development, and increased the bodyweight of neonatal rats with hyperoxia exposure. Our study demonstrates that 18ß-GA has a protective effect on neonatal rats with hyperoxia exposure.

Regulation of calcium oscillations by IP3R and RyR in neonatal rat cardiomyocytes / 西安交通大学学报(医学版)

【Objective】 To explore the roles of 1,4,5-trisphosphate receptor (IP3Rs) and ryanodine receptors (RyRs), the two main Ca2+ release channels in sarcoplasmic reticulum (SR), in the regulation of intracellular Ca2+ oscillations in neonatal rat cardiomyocytes (NRCMs). 【Methods】 We isolated and cultured NRCMs for different days, then loaded them with Ca2+ indicator fura-2 and performed real-time fluorescent imaging. To distinguish the effects of IP3Rs and RyRs, NRCMs were pre-treated with phenylephrine (PE, IP3Rs agonist), caffeine (RyRs agonist), 2-APB (IP3Rs antagonist), and tetracaine (RyRs antagonists), respectively. 【Results】 The cultured monolayer NRCMs showed spontaneous synchronized Ca2+ oscillations. PE activation or 2-APB blockade of IP3Rs increased or reduced the frequency of Ca2+ oscillations in NRCMs, accordingly, with no significant effect on the amplitude of Ca2+ oscillations. Activation of RyRs with caffeine increased the frequency of Ca2+ oscillations, but unsynchronized the intercellular rhythm of calcium release and beating pace, while blocking RyRs with tetracaine completely abolished the Ca2+ oscillations and beats in NRCMs. In addition, the effect of PE stimulation on Ca2+ oscillation frequency gradually decreased along with cultured days. 【Conclusion】 IP3Rs regulate the rhythm of calcium oscillations, whereas RyRs are the main channel for bulky store Ca2+ release.

Traditional Chinese Medicine in Prevention and Treatment of Rheumatoid Arthritis Based on Pyroptosis Theory： A Review / 中国实验方剂学杂志

Pyroptosis is a newly discovered programmed cell death. It is an important natural immune response and has obvious anti-infection function. Studies have shown that pyroptosis plays an important role in the occurrence and development of rheumatoid arthritis. Traditional Chinese medicine（TCM） has unique advantages in the prevention and treatment of rheumatoid arthritis. How to guide TCM to effectively prevent and treat rheumatoid arthritis using pyroptosis theory is a new research hotspot in this field. This paper discussed the overview of pyroptosis theory，its mechanism， signal pathway，and application in the treatment of rheumatoid arthritis as well as the research on the activity of TCM based on pyroptosis theory. It was found that the occurrence of pyroptosis was related to Caspase-1-dependent classical inflammatory body pathway and Caspase-1-independent non classical inflammatory body pathway， and pyroptosis produced distinct regulatory effect on the occurrence，development and treatment of rheumatoid arthritis，which would provide a new strategy for the treatment of rheumatoid arthritis. Additionally，TCM recipes such as Miao ethnomedicine prescription Sidaxue and Duhuo Jishengtang， and a variety of effective components such as punicalagin and paeoniflorin monomer derivatives exerted anti-rheumatic and other biological activities by regulating pyroptosis. This provided a theoretical basis and research ideas for the in-depth study of pyroptosis theory and guiding the prevention and treatment of rheumatoid arthritis with TCM.

Traditional Chinese Medicine in Prevention and Treatment of Rheumatoid Arthritis Based on Pyroptosis Theory： A Review / 中国实验方剂学杂志

Pyroptosis is a newly discovered programmed cell death. It is an important natural immune response and has obvious anti-infection function. Studies have shown that pyroptosis plays an important role in the occurrence and development of rheumatoid arthritis. Traditional Chinese medicine（TCM） has unique advantages in the prevention and treatment of rheumatoid arthritis. How to guide TCM to effectively prevent and treat rheumatoid arthritis using pyroptosis theory is a new research hotspot in this field. This paper discussed the overview of pyroptosis theory，its mechanism， signal pathway，and application in the treatment of rheumatoid arthritis as well as the research on the activity of TCM based on pyroptosis theory. It was found that the occurrence of pyroptosis was related to Caspase-1-dependent classical inflammatory body pathway and Caspase-1-independent non classical inflammatory body pathway， and pyroptosis produced distinct regulatory effect on the occurrence，development and treatment of rheumatoid arthritis，which would provide a new strategy for the treatment of rheumatoid arthritis. Additionally，TCM recipes such as Miao ethnomedicine prescription Sidaxue and Duhuo Jishengtang， and a variety of effective components such as punicalagin and paeoniflorin monomer derivatives exerted anti-rheumatic and other biological activities by regulating pyroptosis. This provided a theoretical basis and research ideas for the in-depth study of pyroptosis theory and guiding the prevention and treatment of rheumatoid arthritis with TCM.

The Specific Connexin 43-Inhibiting Peptide Gap26 Improved Alveolar Development of Neonatal Rats With Hyperoxia Exposure.

Bronchopulmonary dysplasia (BPD) is a common devastating pulmonary complication in preterm infants. Alveolar maldevelopment is the crucial pathological change of BPD highly associated with oxidative stress-mediated excessive apoptosis. Cellular injury can be propagated and amplified by gap junction (GJ)-mediated intercellular communication. Connexin 43 (Cx43) is the most ubiquitous and critical GJ protein. Gap26 is a specific Cx43 mimic peptide, playing as a Cx43-GJ inhibitor. We hypothesized that Cx43-GJ was involved in alveolar maldevelopment of BPD via amplifying oxidative stress signaling and inducing excessive apoptosis. Neonatal Sprague Dawley rats were kept in either normoxia (21% O2) or hyperoxia (85% O2) continuously from postnatal day (PN) 1 to 14 in the presence or absence of Gap26. Moreover, RLE-6TN cells (type II alveolar epithelial cells of rats) were cultured in vitro under normoxia (21% O2) or hyperoxia (85% O2). RLE-6TN cells were treated by N-acetyl cysteine (NAC) (a kind of reactive oxygen species (ROS) scavenger) or Gap26. Morphological properties of lung tissue are detected. Markers associated with Cx43 expression, ROS production, the activity of the ASK1-JNK/p38 signaling pathway, and apoptotic level are detected in vivo and in vitro, respectively. In vitro, the ability of GJ-mediated intercellular communication was examined by dye-coupling assay. In vitro, our results demonstrated ROS increased Cx43 expression and GJ-mediated intercellular communication and Gap26 treatment decreased ROS production, inhibited ASK1-JNK/p38 signaling, and decreased apoptosis. In vivo, we found that hyperoxia exposure resulted in increased ROS production and Cx43 expression, activated ASK1-JNK/p38 signaling, and induced excessive apoptosis. However, Gap26 treatment reversed these changes, thus improving alveolar development in neonatal rats with hyperoxia exposure. In summary, oxidative stress increased Cx43 expression and Cx43-GJ-mediated intercellular communication. And Cx43-GJ-mediated intercellular communication amplified oxidative stress signaling, inducing excessive apoptosis via the ASK1-JNK/p38 signaling pathway. The specific connexin 43-inhibiting peptide Gap26 was a novel therapeutic strategy to improve the alveolar development of BPD.

Effects of Hyperoxia on Mitochondrial Homeostasis: Are Mitochondria the Hub for Bronchopulmonary Dysplasia?

Mitochondria are involved in energy metabolism and redox reactions in the cell. Emerging data indicate that mitochondria play an essential role in physiological and pathological processes of neonatal lung development. Mitochondrial damage due to exposure to high concentrations of oxygen is an indeed important factor for simplification of lung structure and development of bronchopulmonary dysplasia (BPD), as reported in humans and rodent models. Here, we comprehensively review research that have determined the effects of oxygen environment on alveolar development and morphology, summarize changes in mitochondria under high oxygen concentrations, and discuss several mitochondrial mechanisms that may affect cell plasticity and their effects on BPD. Thus, the pathophysiological effects of mitochondria may provide insights into targeted mitochondrial and BPD therapy.

Metabolic network of ammonium in cereal vinegar solid-state fermentation and its response to acid stress.

Shanxi aged vinegar (SAV), a Chinese traditional vinegar, is produced by various microorganisms. Ammonium is an important nitrogen source for microorganisms and a key intermediate for the utilization of non-ammonium nitrogen sources. In this work, an ammonium metabolic network during SAV fermentation was constructed through the meta-transcriptomic analysis of in situ samples, and the potential mechanism of acid affecting ammonium metabolism was revealed. The results showed that ammonium was enriched as the acidity increased. Meta-transcriptomic analysis showed that the conversion of glutamine to ammonia is the key pathway of ammonium metabolism in vinegar and that Lactobacillus and Acetobacter are the dominant genera. The construction and analysis of the metabolic network showed that amino acid metabolism, nucleic acid metabolism, pentose phosphate pathway and energy metabolism were enhanced to resist acid damage to the intracellular environment and cell structures. The enhancement of nitrogen assimilation provides nitrogen for metabolic pathways that resist acid cytotoxicity. In addition, the concentration gradient allows ammonium to diffuse outside the cell, which causes ammonium to accumulate during fermentation.

Isolation and identification of unknown impurities of alogliptin benzoate / 中国药科大学学报

@#By silica gel column chromatography, solvent extraction and preparative high performance liquid chromatography (HPLC), four new related substance were isolated and purified from the mass production and preparation process of alogliptin benzoate. Then it was analyzed and confirmed by various spectrum identification methods such as nuclear magnetic resonance (NMR) spectroscopy, high-resolution mass spectrometry (HR-MS) and Fourier-transform infrared spectroscopy (FTIR) according to its physical and chemical properties. The chemical structures of the four related substances produced in each step of the synthesis process of alogliptin benzoate were determined, and they were named as impurities L, M, T, and V. These four related substances were new impurities which were found for the first time. The isolation and identification of these impurities are of great importance to the quality control of alogliptin benzoate, and the optimization of manufacturing process.

Design and implementation of a parallel geographically weighted k-nearest neighbor classifier.

The development of high-performance classifiers represents an important step in improving the timeliness of remote sensing classification in the era of high spatial resolution. Geographically weighted k-nearest neighbors (gwk-NN)-a classifier that incorporates spatial information into the traditional k-NN classifier-has demonstrated to be better at mitigating salt-and-pepper noise and misclassification. However, the integration of spatial dependence relationships into spectral information is computationally intensive. To improve computing performance, this paper discusses two commonly used parallel strategies-data and task parallelism-used to parallelize the gwk-NN classifier in the model training and classification stages, and implements the parallel algorithm by calling MPI and GDAL in the C++ development environment on a standalone eight-core computer. We further investigate the potential performance of dual parallelism (the simultaneous exploitation of data and task parallelism) in image classification. The experimental results demonstrate that the parallel gwk-NN classifier can improve the efficiency of high-resolution, remotely sensed images with multiple land cover types. Specifically, data parallelism is more effective than task parallelism in both model training and classification stages because of the minor role of parallel overhead in total execution time. In addition, dual parallelism can take advantage of data and task parallel strategies in the image classification stage, as evidenced by the two largest speedups attained under dual parallelism I (5.28×) and II (5.73×). Comparatively, dual parallelism II, in which priority is given to data decomposition, achieves the best performance by overlapping computation and data transmission, which is compatible with the current trend toward multicore architectures.

Effects of different concentration oxygen on the lung development of neonatal rats / 中国小儿急救医学

Objective To investigate the effects of different concentration hyperoxic exposure on the lung development of neonatal rats for providing theoretical basis for the preparation of bronchopulmonary dys-plasia model. Methods A total of 128 newborn rats were randomly and equally assigned to one of the fol-lowing four groups:group A(FiO2 >0. 9,n＝32),group B ( FiO2 ＝0. 6,n＝32),group C(FiO2 ＝0. 4,n＝32) and the air group(21% O2,n＝32). Lung tissue were collected at day 3,7,14 and 21 for histological analysis. Body weights were recorded,pulmonary morphology and radical alveoli count(RAC),mean alveolar diameter(MAD),alveolar septal thickness(AST) were carried out. Results Compared with the air group of the same time,the body weight of group A significantly decreased at 3 d( P <0. 05),the body weight of group B significantly decreased at 7 d(P<0. 05),the body weight of group C slightly decreased at every time point,but there was no statistical significance(P>0. 05). HE staining showed that the alveolar cavity signifi-cantly increased,alveolar structure was simplified and the alveolar spacing was thickened in different degrees in group A and group B. Furthermore,the reduction in the number of alveoli was more obvious and the alveo-lar septum was thicker in group A. The change of alveoli in group C was obviously weaker than group A and group B. The RAC of group A and group B were significantly lower than those in the air group(P<0. 05). The RAC of group C was slightly lower than those in the air group,and had statistical significance at 14 d (P<0. 05). The MAD and AST of group A and group B were significantly higher than those in the air group at 7 d (P<0. 05). The MAD and AST of group C decreased slightly over time,and had statistical signifi-cance at 21 d( P<0. 05). Conclusion Different concentrations of oxygen can have an impact on alveolar development. Severe alveolar dysplasia can be seen after continuous inhalation of more than 60% oxygen concentration. It provides a model basis for the study of the pathogenesis of bronchopulmonary dysplasia.

Regulatory effect of vitamin D on the expression of occludin in the intestinal epithelial cells of neonatal ;rats with necrotizing enterocolitis / 中国小儿急救医学

Objective To investigate the expression of occludin in the intestinal epithelial cells of neonatal rats with necrotizing enterocolitis ( NEC) . The influence of vitamin D on NEC and the expression of occludin was also explored. Methods Sixty neonatal Wistar rats from different litters were divided into four groups 48 hours after birth:10 in the breast-fed+ control group,10 in the breast-fed +vitamin D group,20 in the NEC+ control group and 20 in the NEC+ vitamin D group. In groups with NEC,neonatal rats were sep-arated from their mothers and treated with rat milk substitute+hypoxia+hypothermia. In groups with vitamin D treatment,paricalcitol was given through intraperitoneal injection 30 minutes before,one day and two days after the induction of NEC. The tissue was harvested from the ileum of the rats 72 hours after induction of NEC. Microscopically,the tissue was assessed according to the Nadler scoring system. The expression and location of occludin was observed after immunofluorescence staining. Western blotting was performed and quantified to compare the expression of occludin among groups. Results In NEC rats,the intestinal structure was destructed. Separation of the submucosal or muscular layer,discharge or disappearance of the villa was accompanied by necrosis of the intestinal cells. Vitamin D treatment could significantly alleviate those chan-ges,with the Nadler score 1. 70 ± 0. 21 compared to 2. 90 ± 0. 23 without vitamin D treatment ( P<0. 01 ) . The expression of occludin was decreased in NEC rats and vitamin D could partly rescue this decrease (P<0. 01). The distribution of occludin was sparse and discontinuous in NEC rats while after vitamin D treatment,the distribution was maintained even and continuous. Conclusion The expression of occludin in intestinal epithelial cells is significantly reduced in NEC rat. Vitamin D treatment may inhibit the development of NEC by maintaining the expression of occludin.

Effect of sandblasting on bending strength and subcritical crack growth of the dental zirconia ceramics / 中华口腔医学杂志

Objective@#To evaluate the effect of sandblasting on bending strength and subcritical crack growth (SCG) under cyclic loading of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics.@*Methods@#After being polished, sixty bar-shaped specimens of Y-TZP (Wieland zirconia ceramics) were assigned to two groups (n=30) according to the random number table, the sandblasting group (SG) which was treated with sandblasting and the control group (CG) which remained untouched. In each group, half of the specimens (n=15) were subjected to bending strength test, and the results were examined by Weibull statistics and analyzed with ANOVA. The other 15 specimens in each group were subjected to fatigue tests. The results were examined by Weibull statistics and subcritical crack propagation rates were calculated.@*Results@#The bending strengths of SG and CG were (1 291±133) and (1 140±124) MPa (F=10.117, P=0.004), and the Weibull modules of the two groups were 11.06 and 10.64 respectively. The crack growth rate of SCG of SG was lower than that of CG under the same cyclic loading.@*Conclusions@#Proper sandblasting on Y-TZP ceramic can increase its bending strength and resistance to SCG.

Reliability of flexural strength and subcritical crack growth of two kinds of zirconia ceramics / 实用口腔医学杂志

Objective:To evaluate the reliability of flexural strength and subcritical crack growth(SCG)of WL and HT zirconia ce-ramics under cyclic loading.Methods:Bar-shaped speciments of WL(n =30)and HT(n =30)were fabricated and loaded in three-point bending and cyclically fatigued.The flexural strength and the number of cycles to fracture were obtained from three-point flexural test and cyclic fatigue test respectively.Data were examined using Weibull statistics.Pairs law was used to analysize the subcritical crack growth(SCG),the behavior of which was described in terms of crack velocity as a function of maximum stress intensity factor (KImax ).Results:The Weibull module(m)of WL and HT was 10.64 and 12.04,the stress corrosion cracking susceptive indexes(n) 23.71 and 32.87,the SCG 90% and 76.7%,the KImax 49.6% and 50.9% of its maximum stress intensity factor(KIC ),respectively. Conclusion:WL and HT produce pronounced SCG.The minimum fatigue crack growth rate of HT is lower than that of WL(νHT <νWL ).

Fluoride release and recharge properties of six restorative materials / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the F(-) releasing and recharging properties of six dental restorative materials.</p><p><b>METHODS</b>Disc specimens 10 mm in diameter and 1 mm in thickness were prepared from 6 different dental restorative materials: Fuji VII [glass ionomer cement (GIC)], Fuji II LC (light-curing, GIC), Beautifil (giomer), Compoglass F (compomer), Charisma (composite) and Experimental I (a fluoride releasing composite), with 10 discs for each material. Specimens were dipped in 5 ml deionized water and F(-) release was detected using a fluoride-specific ion electrode every day from 1-7 days and every three days from 8-28 days. On day 28, specimens were exposed to a fluoride foam for 4 min and then dipped in water, then the F(-) concentration was detected every day for a week. The specimens were exposed to fluoride foam and fluoride release was detected repeatedly for three times.</p><p><b>RESULTS</b>All materials presented the highest F(-) release on the first day after dipping and the F(-) release sharply decreased after 24 h and slowly decreased after 3 days. On the first day, Fuji VII presented the highest F(-) release[(99.68±15.21) µg×cm(-2)×d(-1)], followed by Fuji II LC [(37.12±1.67) µg×cm(-2)×d(-1)], Experimental I [(22.93±1.53) µg×cm(-2)×d(-1)], Compoglass F[(15.28±0.70) µg×cm(-2)×d(-1)], Beautifil[(2.40±0.52) µg×cm(-2)×d(-1)] and Charisma[(0.11±0.02) µg×cm(-2)×d(-1)]. Within 28 days of dipping, both Fuji VII and Fuji II LC released more F(-) than other materials did(P < 0.05), followed by Compoglass F and Experimental I, and Beautifil and Charisma released the least F(-)(P < 0.01). After F(-) uptake, all materials released the highest F- on the first day and presented sharply decrease after 24 h and slowly decrease after 2 days. On the first day after F(-) uptake, Fuji VII presented the highest F(-) release (>40 µg×cm(-2) ×d(-1)), much more than other materials(P < 0.01), followed by Fuji II LC(>25 µg×cm(-2) ×d(-1)). Beautifil, Compoglass F and Experimental I were close in F(-) release value(15- 20 µg × cm(-2) × d(-1)), and Charisma showed the lowest F(-) release.</p><p><b>CONCLUSIONS</b>Two glass ionomers were shown to have highest capacity in F(-) release and uptake, followed by compomer and fluoride releasing composite. Composite demonstrated the lowest F(-) release and uptake and Giomer was comparable to composite in F(-) release and to compomer and fluoride releasing composite in F(-) uptake.</p>

Effects of different fluorides and their loading on the release properties of composite resin / 第三军医大学学报

Objective To evaluate the effects of different kinds of fluorides and their loading on the fluoride releasing characteristics of fluoride containing composite resins. Methods Two paste type of composite resin, containing NaF and K 2TiF 6 respectively, were prepared. The composite resins were based on Bis GMA/TEGDMA resin and loaded with fluoride at 5%, 10%, 15% and 20% by weight, and a non fluoridated composite resin was prepared as the control. Six standardized discs (6 mm?3 mm) were made of each material, and three discs of each material were stored in plastic vials containing 5 ml deionized water at 37 ℃ respectively and the others in artificial saliva. The water and the artificial saliva were changed every 24 hours. An ion selective electrode (9606BN Orion) connected to an ion analyzer (720A Orion) was used to determine the amount of fluoride released on days 8, 15, 22, 29 and 62. The data were analyzed using t tests. Results All of the fluoride containing materials demonstrated a higher fluoride release than that from non fluoride control materials. The composite resin containing NaF released significantly more fluoride than that of K 2TiF 6. All materials showed a significantly higher release of fluoride in water than in artificial saliva ( P

Clinical application of a kind of flexible gingival epithesis material / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The aim of this paper is to introduce the clinical and laboratory procedures of fabricating silicone gingival epithesis and evaluate the long-term effects of the epithesis.</p><p><b>METHODS</b>Flexible gingival epithesises were fabricated by the same way of fabricating partial denture, and their effects were evaluated in 31 patients by following up for 8-20 months.</p><p><b>RESULTS</b>Patients' responses to appearance showed that their esthetic appearance had been much improved in all of the patients and the comfort and retention of their epithesises varied from good to excellent in almost all the patients. Discoloration of the epithesises was noticed by the patients within ten months in average. Doctors' examination confirmed patients' responses, and caries was detected at the necks of teeth covered by epithesises and slight gingivititis was discovered in the area under the epithesises in two cases.</p><p><b>CONCLUSION</b>Flexible gingival epithesis is a simple and effective method for correcting gingival recession, and the fabrication is simple and don't need special equipment. However, discoloration of the epithesis remains a problem.</p>

Microtensile bond strengths of three adhesives to normal or caries-affected dentine / 实用口腔医学杂志

0.05),respectively.The fractured adheisive dentin surface was mainly a mixed failue mode.Conclusions:There is no significant difference in the bond strengths of each of the three bonding agents to ND and CAD.

Laser scanning confocal microscope study of wet bonding interface on different dentin bonding surfaces / 实用口腔医学杂志

Objective: To study the bonding interface characteristic of five wet bonding systems while bonding on different dentin bonding surfaces. Methods: Rhodamine B was used to label five adhesives(OptiBond Sol o,Single Bond,Gluma One-Bond,Bond-1 and One-Step) in consistency of 0.1%, an d the bonding interface of the 5 wet bonding systems on dry or wet dentin surfa ces was observed with laser scanning confocal microscope. Results: All five bonding systems could infiltrate well into dentin bonding interface when bonding on wet dentin surface. The fluorescence confocal images gave eviden ce of the adhesives penetrated into the widened tubules, lateral tubules and dem ineralized peritubular dentin. Little discontinuity in dentin tubular was observ ed in the images, especially in those of alcohol-water-based adhesives. When b onded in dry dentin surface, the hybrid thickness of acetone-based adhesives de creased significantly. Conclusion: The penetration ability of ad hesives may be reduced significantly on dry dentin surface.

The effect of roughness on adhesive properties of polymethyl methacrylate and SY-1 silicone elastomer / 实用口腔医学杂志

Objective: To evaluate the effect of roughness on adhesive properties of polymethyl methacrylate and SY-1 silicone elastomer.Methods:5 specimens of polymethyl methacrylate were polished by sand paper of different standards and the roughness of polymethyl methacrylate surfaces were measured by roughmeter. The tension strength between polymethyl methacrylate with different degrees of roughness and SY-1 silicone elastomer were tested according to national standards. Results: After the surfaces of polymethyl methacrylate were respectively polished by sand paper of the standard 160,320 and 800, the sufrace roughness decreased, but the tension strength between polymethy1 and SY-1 silicone elastomer was increased(P

Application of GP-084 cellular silicone rubber may reduce the weight and hardness of facial prostheses / 实用口腔医学杂志

Objective: To study the feasibility of sandwich structure made by GP-084 cellular silicone rubber and SY-1 silicone elastomer in preparing facial prostheses. Methods: Samples of SY-1 silicone or GP-084 or sandwich of both were made in the size of 100 cm 2. Sandwich structure was made of SY-1 silicone as the top and bottom lyers of 1 mm in thickness and GP-084 cellular silicone as the middle layer of 23 mm in thickness. The weight density and Shore﹝A﹞hardness of the samples were measured. Results: The weight density (?10 3 kg/m 2) of GP-084, SY-1 silicone rubber and the sandwich structure was 0.411? 0.003, 1.245?0.024 and 0.679? 0.002 respectively(P