Preparation, water absorption and solubility of a new Eucommia ulmoides gum composite soft denture liner / 中国组织工程研究

BACKGROUND: The most common soft liners currently used in the clinic are silicone rubbers and acrylics, but both of them have deficiencies. Therefore, the development of soft lining materials with stability, excellent performance, and antibacterial properties is of important clinical significance. OBJECTIVE: To prepare a soft lining material with high elasticity on the basis of excellent characteristics of Eucommia ulmoides gum, and to preliminarily explore its water absorption and solubility. METHODS: The basic formula was made based on the existing formula of elastic Eucommia ulmoides gum and medical rubber, in combination with the specific requirements of denture lining materials. The ratio of Eucommia ulmoides to butadiene rubber was set to be 10:90, 30:70, 50:50, 70:30 and 90:10, and the new Eucommia ulmoides gum composite soft denture liners were then prepared. Acrylate self-curing soft lining material and Silagum silicone rubber denture soft lining material served as controls. Afterwards, the samples were put into distilled water or artificial saliva for 7 and 30 days, and the value of water absorption and water solubility were calculated. RESULTS AND CONCLUSION: (1) In the artificial saliva for 7 and 30 days, the water absorption rate and solubility of samples in different ratio groups were close to those in the Silagum group, but extremely lower than those in the acrylate group. (2) In the distilled water for 7 and 30 days, the water absorption rate and solubility of samples in different ratio groups were close to those in the Silagum group, but extremely lower than those in the acrylate group. (3) The water absorption rate and solubility of the acrylate group were significantly higher than those in the other groups at 7 and 30 days of immersion in the artificial saliva or distilled water (P < 0.05). (4) After 7 and 30 days of immersion, the water absorption rate of the same sample in the artificial saliva was significantly lower than that in the distilled water. Wile at 7 days of immersion, the samples in the 30:70 and 50:50 groups showed a lower solubility in the artificial saliva than in the distilled water (P < 0.05), and at 30 days of immersion, the samples in the 30:70, 50:50, 70:30 and 90:10 groups showed a lower solubility in the artificial saliva than in the distilled water (P < 0.05). (5) In the artificial saliva, there was no significant difference in the solubility in the 50:50 and 70:30 groups at 7 and 30 days of immersion (P> 0.05), while the solubility in the other groups exhibited significant differences at different observational times (P < 0.05). In the distilled water, there was no significant difference in the solubility in the 10:90 and 30:70 groups at 7 and 30 days of immersion (P> 0.05), while the solubility in the other groups exhibited significant differences at different observational times (P < 0.05). To conclude, the water absorption of Eucommia ulmoides gum composite soft denture liner is close to Silagum, but significantly less than that of acrylate soft lining materials, and the solubility remains at a very low level.

Remineralization of demineralized dentin induced by bioactive glass NovaMin / 中南大学学报(医学版)

To explore the remineralization effect of bioactive glass NovaMin on demineralized dentin specimens, and to study the physical and chemical properties of formed structure at dentin surface.
 Methods: One mm-thickness coronal dentin slices were soaked in ethylene diamine tetraacetic acid (EDTA) for 48 h to prepare the completely demineralized dentin specimens and they were divided into 2 groups: an artificial saliva group (control group) and a NovaMin powder group. The specimens were treated with artificial saliva or NovaMin powder for 2 min (2 times every day), and the interval was 8 hours. Then, the specimens were soaked in the remineralization solution. After 7 days, the scanning electron microscope (SEM), energy dispersive X-ray (EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) were used to detect dentin morphology, the physical and chemical properties of the formed structure at dentin surface.
 Results: The results of SEM showed that a defined surface layer in the NovaMin powder group could be observed in the SEM imaging at the 7th day, which completely occluded dentinal tubules; the EDX, ATR-FTIR and XRD analysis found that the mineralized layer formed at dentin surface was mainly composed of calcium and phosphate elements, which was similar to the hydroxyapatite-like crystal. However, there were no materials formed at the dentin surface in the control group, and the dentinal tubules were still open.
 Conclusion: NovaMin can remineralize the demineralized dentin specimens and occlude the dentinal tubules in hydroxyapatite-like crystal structure.

Clinical effect of all-ceramic restorations and metal-ceramic restorations:A Meta-analysis / 实用口腔医学杂志

Objective:To evaluate the clinical outcome of all-ceramic and metal-ceramic restorations by means of Meta-analysis. Methods:The relevant randomized controlled trials ( RCTs) were electronically searched from PubMed, the Cochrane Library, EM-base, SinoMed, Weipu databases, CNKI and Wanfang. After data extraction and bias evaluation the Meta-analysis was conducted using RevMan 5. 3 software. Results:Finally 15 RCTs involving 768 all-ceramic restorations and 1386 Metal-ceramic restorations met the eli-gibility criteria. The results showed that, compared with metal-ceramic restorations, all-ceramic restorations could significantly decrease the risk of gingivitis(RR=0. 30,95%CI=0. 10-0. 90, P=0. 03),could decrease secondary caries and improve the satisfaction of cervical discoloration and marginal adaptation but without significant difference. There was no difference in color match and chipping of the veneering ceramics. However, all-ceramic restorations may lead to loss of the abutment tooth vitality. The risk of all-ceramic frame-work fracture while adopting fixed bridges was significantly higher(RR=6. 24, 95%CI=1. 20 -32. 41, P=0. 03). Conclusion:Based on the existing limited evidence,the efficacy of all-ceramic restorations is better than metal-ceramic restorations. But the intensity of all-ceramic bridges needs to be improved.

Feasibility ofEucommia ulmoides gum as a root canal filling material / 中国组织工程研究

BACKGROUND:Eucommia ulmoides gum has good thermoplastics, liquidity, bondability and antimicrobial properties. However, the application of Eucommia ulmoides gum as a root canal filing material is rarely reported. OBJECTIVE: To compare the different contents of gas phase nano-silica on mechanical performance of composite material taking the gutta-percha as the matrix, and observe the effect of the root canal filing. METHODS:Four kind of root canal filing materials were prepared through adding barium sulfate (20%), nano-hydroxyapatite (10%) and different contents of gutta-percha and gas phase nano-silica (40% and 15%, 45% and 20%, 50% and 25%, 55% and 30%). PureEucommia ulmoidesgum served as the blank control. The mechanical properties (hardness, tensile strength and rupture elongation rate) of those five materials were detected. Furthermore, four kinds of composite materials, pureEucommia ulmoidesgum and Gutta-Percha Pelets were filed into the fresh extracted premolar root canal by using Obtura II technology. The effect of root canal filing was observed under X-ray and scanning electron microscopy.RESULTS AND CONCLUSION: Along with the increase of the content of gas phase nano-silica, the hardness of Eucommia ulmoides gum composite material increased, tensile strength increased firstly and then decreased, and rupture elongation rate decreased. PureEucommia ulmoides gum was transmitted to the X-ray and no image of filing material was obtained. Four kinds of composite materials were resistant to X-ray, and images showed that al composite materials were equaly filed into the root canal, without cacuole, and were in contact with the root canal inner wal, showing good filing effect. Scanning electron microscopy showed that, fingerlike projections were the longest at the surface of pureEucommia ulmoides gum; as the content of gas phase nano-silica increased, fingerlike projection length reduced at the surface of composite materials.Eucommia ulmoides gum composite materials could be developed as a canal filing material under heat flow condition.

Biocompatibility of nano fluoridated hydroxyapatite for dental implants / 中国组织工程研究

BACKGROUND:Few reports focus on biocompatibility of nano fluoridated hydroxyapatite for dental implants. OBJECTIVE:To investigate the biocompatibility in vitro of nano fluoridated hydroxyapatite modified for dental implants. METHODS:We utilized sol-gel method to prepare nano fluoridated hydroxyapatite and nanohydroxyapatite powders. (1) Hemolysis test:0.01, 0.15, 0.2 g/L nano fluorinated hydroxyapatite solution, saline and distil ed water at a volume of 10 mL were added into 0.2 mL diluted rabbit anti-coagulation blood samples, respectively. Then the supernatant was detected by absorbance values. (2) In vitro cytotoxicity test:Passage 2 L929 cel s were respectively cultured in culture media containing 100%, 50%nano fluorinated hydroxyapatite extract, 100%hydroxyapatite extract, phenol solution and RPMI1640. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was employed to measure absorbance values at days 2, 4, 7 of culture. RESULTS AND CONCLUSION:Hemolysis test in vitro showed the hemolysis rates of nano fluorinated hydroxyapatite groups were less than 5%, which were accorded with haemolysis demand of medical materials. The cytotoxicity test in vitro showed during cultivation, the adherence rate of L929 cel s cultured in 100%and 50%nano fluorinated hydroxyapatite extracts were increasing and cel density was rising up. Cel s were fusiform or polygon, which had no evident differences from negative controls in morphology. Nano fluorinated hydroxyapatite showed nontoxic to L929 cel s in vitro.

Effects of bleaching agents on the microleakage of class V cavities restored with glass-ionomer cements / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effects of a bleaching gel and a whitening strip on the microleakage of three different glass-ionomer cements.</p><p><b>METHODS</b>Forty-five freshly extracted human premolars were used and class V cavity was prepared on the buccal and lingual surfaces. The teeth were randomly assigned to A, B and C groups and restored as follows: Conventional strengthen glass-ionomer cement (Ketac Molar Easymix), compomer (F2000) and compomer (Dyract AP). Teeth were kept in distilled water at 37 degrees C for 7 days. Then the specimens were thermocycled for 500 times. Each group was randomly divided into 3 subgroups which were treated for 21 days with one of the following: Whitening strip (14% hydrogen peroxide), bleaching gel (10% carbamide peroxide), or distilled water (control). After bleaching, the teeth were placed in a solution of basic fuchsin dye for 24 hours, then the teeth were sectioned longitudinally to evaluate the dye penetration. The depth of staining along the tooth restoration interface was recorded with a stereomicroscope.</p><p><b>RESULTS</b>There were no signicant differences between the two bleaching agents in microleakage of restorations (P>0.05). The two bleaching agents did not significantly affect the microleakage of compomer (P>0.05), whereas the microleakage of glass-ionomer cement in the experimental groups was higher than that in the control group (P<0.05).</p><p><b>CONCLUSION</b>There are no significant differences in microleakage of restorations between bleaching gel (10% carbamide peroxide) and whitening strip (14% hydrogen peroxide). The two bleaching agents do not significantly affect the microleakage of compomer but adversely affect the microleakage of strengthen glass-ionomer cement.</p>

Expression of EphA7 and MTDH and clinicopathological significance in the squamous cell cancer of the tongue / 中南大学学报(医学版)

OBJECTIVE@#To determine the expression levels of EphA7 and MTDH and detect their clinicopathological significance in the peritumoral normal tissues and the squamous cell cancer of the tongue.@*METHODS@#Envision immunohistochemistry was used to assay the expression levels of EphA7 and MTDH in the conventional paraffin-embedded sections from specimens of squamous cell cancer (n=45) and peritumoral normal tissues (n=10).@*RESULTS@#The positIVe rates of EphA7 and MTDH were significantly higher in the squamous cell cancer than those in the peritumoral normal tissues ( χ(2)(EphA7)=4.14; χ(2)(MTDH)= 5.25; P < 0.05). The positIVe rates of EphA7 and MTDH expression were significantly lower in the cases of histological grade I-II,clinical stage I-II, and no-metastasis of neck lymph node than those in the histological grade III-IV, clinical stage III-IV, and metastasis of neck lymph node (P <0.05 or P <0.01).@*CONCLUSION@#The expression levels of EphA7 and/or MTDH might have important effect on the carcinogenesis and progression of tongue cancer. Overexpression of EphA7 and/or MTDH might have poor prognosis.

Influence of SiO2 films on color reproduction of Ni-Cr alloy porcelain crowns / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study whether SiO2 films will influence the color of Ni-Cr metal ceramic restorations.</p><p><b>METHODS</b>For the film plating experimental group, Sol-gel method was employed to apply SiO2 films to the surface of the Ni-Cr copings, while no coating was applied for the non-film-plating control group. Veneering porcelains were then applied subsequently, and a total of 12 B2-colored maxillary incisor metal ceramic crowns were fabricated with 6 crowns in each group. A ShadeEye Ncc computer-aided colorimeter was employed to measure the shade of the samples, as well as 6 B2(Vitapan classical vita color tabs) shade standards. The color was expressed as C1E-1976-Lab coordinates.</p><p><b>RESULTS</b>There was a statistically significant color difference between all metal ceramic crowns and the B2 shade standards (delta E>1.5). The L*, a*, b* values of all crowns were higher than those of the B2 shade standards, and the crowns were typically yellower or redder. While neither significant color difference nor difference in shade values was observed between the film plating experimental group and non-film-plating control group (delta E<1.5).</p><p><b>CONCLUSION</b>SiO2 films applied to the Ni-Cr copings by means of Sol-gel technique do not impact the final color of the metal ceramic restorations.</p>

In vitro fracture resistance of endodontically treated anterior teeth with varying ferrule heights and configurations with glass-fiber post / 实用口腔医学杂志

The extracted human maxillary central incisors were endodontically treated and restored with glass-fiber post. Then they were randomly divided into four groups and tested. Results showed that groups with ferrule more than 2 mm had higher fracture resistence than others.

A in vitro study of coronal microleakage of different post and cement systems / 实用口腔医学杂志

Objective: To compare the coronal sealing abilities of different post and cement systems through measuring the value of leakage by using dye method. Methods: Fifty human mandibular premolars with single canal were divided into 6 groups randomly. A group: roots sealed by temporary material, B group: roots restored with fiber post adhered with composite resin cement, C group: roots restored with casting metal post and core adhered with composite resin and zinc phosphate cement, D group: positive control, E group: negative control. After finishing preparation and restoration of roots, microleakage was determined by using dye method. Results: The groups restored with any post and core system produced significantly less microleakage than temporary material sealing group(P<0.05). But no differences were detected between two groups bonded with the composite resin cement (P>0.05). Posts adhered with zinc phosphate luting agent produced more leakage than those with composite resin cement(P<0.05). Conclusion: Luting agent can decrease the coronal microleakage. Composite resin cement provides better sealing ability.

Effects of cyclosporin A on the levels of intercellular adhesion molecule-1 expressed by oral fibroblasts / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effects of cyclosporin A (CSA) on the level of intercellular adhesion molecule-1 (ICAM-1) expressed by oral fibroblasts (FB).</p><p><b>METHODS</b>The fibroblasts were obtained from normal buccal mucosa (NM-FB) and cultured in vitro. Then the levels of ICAM-1 expressed by fibroblasts incubated with or without CSA in the presence of 10% fetal calf serum for 48 hours at 37 degrees C in 5% CO(2) and air were monitored by using cell-based ELISA for ICAM-1.</p><p><b>RESULTS</b>We demonstrated that NM-FB had ICAM-1 expression (A = 0.324 +/- 0.030), and after 48 hours incubated with CSA the ICAM-1 levels expressed by oral buccal mucosa fibroblasts were dose-dependently decreased.</p><p><b>CONCLUSIONS</b>CSA reduces the levels of ICAM-1 expressed by oral mucosal FB, and may be useful in the treatment of some oral mucosal disorders.</p>

Speech outcomes of the obturator prostheses for maxillary defects / 实用口腔医学杂志

Objective:To evaluate speech outcomes following prosthetic obturation of maxillary defects.Methods:The speech intelligibility(SI)of 21 patients with maxillary defects with and without prostheses was measured postoperatively.In addition,the acoustic characteristics of vowels of 21 individuals were analyzed with and without an obturator in place by sound spectrograph.Results:Following the placement of maxillary obturator prostheses,there was significant improvement in SI.The mean SI score of the patients without and with the prosthesis was(23.2?7.4)% and(81.8?9.4)% respectively(P

Effects of dexamethasone on proliferation and expression of intercellular adhension molecules by human oral fibroblasts / 中国免疫学杂志

Objective:Dexamethasone (DEX) has been proved to be an effective therapy for a variety of oral mucosal disorders, especially for oral submucous fibrosis(OSF) .The mechanisms behind its therapeutic effects are not known but have largely been ascribed to its anti proliferation and immunosuppressive effects. The recruitment, extravagation and retention of leucocytes which may play an important role in the development of oral mucosal disorders depends in part on the interaction of LFA 1 with its ligand intercellular adhension molecules(ICAM 1).The study aimed to investigate the effects of DEX on proliferation and expression of ICAM 1 by human oral fibroblasts (FB).Methods:The fibroblasts were obtained from normal buccal mucosa (NM FB) and OSF buccal mucosa (OSF FB) and cultured in vitro. Then the cell proliferation of fibroblasts incubated with or without DEX in the presence of 10%fetal calf serum for 48 hours at 37℃ in 5%CO 2 and air were monitored by use of thiazolyl blue (MTT) assay and the level of ICAM 1 expressed by fibroblasts were monitored by using cell based ELSA for ICAM 1.Results:OSF FB had an increased proliferation compared to NM FB and DEX inhibited fibroblast proliferation in a concentration dependent manner; OSF FB produced ICAM 1 at high levels and DEX decreased ICAM 1 expression levels on both cell types.Conclusion:DEX can directly inhibit human oral fibroblasts proliferation and reduces the levels of ICAM 1 expressed by oral mucosal FB, and may be useful in the treatment of some oral mucosal disorders.