Antioxidant and antibacterial activities of extracts from Conyza bonariensis growing in Yemen

This study aims to examine the antioxidant and antibacterial activities and phenolic contents of Conyza bonariensis growing in Yemen. The whole plants of C. bonariensis were ultrasonically extracted by ethanol. The antioxidant activity of the extract was determined by 2,2-diphenyl-1-picrylhydrazyl [DPPH] and beta -carotene bleaching [BCB]. The effectiveness of the extract on the growth inhibition of some indicators of foodborne illness bacteria were investigated by agar well diffusion assay. The total phenols [TP], total flavonoids [TF], total tannins [TT], and total anthocyanins [TA] were determined by Folin-Ciocalteu method, aluminium chloride method, Folin and Ciocalteu method, and pH-differential method, respectively. The extract of C. bonariensis possessed TP 144.1 mg/g, TF 143 mg/g, TT 0.99mg/g, and TA 0.97mg 100g, with 94.57% inhibition of DPPH and 92.47% inhibition of BCB, and strong inhibitory effects against tested bacteria, which was approximate to those of peel extract of Punica granatum

Isolation and characterization of dental follicle cells from adult human dental follicle tissues / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To isolate and characterize the dental follicle cells (DFC) from dental follicle (DF) tissues of normal human impacted third molars.</p><p><b>METHODS</b>DFC were isolated from the DF tissues of healthy young human impacted third molars. A limited dilution culture was used to assess DFC colony-forming efficiency. The expressions of Stro-1, Notch-1 and nestin in DFC were detected by immunohistochemistry analysis. The primary DFC cultures were subjected to a variety of treatment modes: osteogenic, adipogenic and chondrogenic differentiation. DFC and periodontal ligament cells (PDLC) proliferation abilities were compared by methyl thiazolyl tetrazolium (MTT) assay. The expressions of tenascin-N and F-spondin in DFC and PDLC were evaluated by reverse transcriptase polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>Most DFC were spindle fibroblast-like cells. DFC cultures formed colonies from passage 1 cells and the frequency of colony forming efficiency (CFE) was 3.70%. Some of the DFC were stained positively for Stro-1 and almost all the DFC were stained positively for Notch-1 and nestin. DFC cultures displayed multipotential characteristics following fate-specific inductions for 21 days. Alizarin red positive condensed nodules were detected following osteogenic induction, oil red-positive lipid vacuoles were generated using adipogenic induction and collagen-II was revealed following chondrogenic induction by immunohistochemistry. On day 3 and 5, DFC (0.20 ± 0.01, 0.51 ± 0.09) showed a better cell activity than PDLC (0.16 ± 0.03, 0.47 ± 0.07) (P > 0.05). On day 7, DFC (1.03 ± 0.11) exhibited a higher proliferation rate than PDLC (0.93 ± 0.09) (P < 0.05). RT-PCR results showed that tenascin-N was not expressed in DFC, but expressed moderately in PDLC. F-spondin was expressed strongly in DFC, while not expressed in PDLC.</p><p><b>CONCLUSIONS</b>DFC from ectomesenchymal tissues showed a good viability and contained cells similar to the mesenchymal stem cells. It may be used as a novel cell source for periodontium regeneration.</p>

Influence of timing of coronal preparation on microleakage of fiber post and core systems / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the microleakage of fiber post and core systems after high-speed handpiece preparation at different time points.</p><p><b>METHODS</b>The crowns of forty-five extracted human premolar were removed and the roots were endodontically treated. The samples were devided into five groups. Root canal preparation was performed on each premolar followed by fiber post cementation and core build up. Tooth preparation was applied at 5 min in group 1, at 15 min in group 2 and at 30 min in group 3 after post cementation. Five teeth with only 5 mm apical sealing were served as a positive control group, and ten with fiber post and core build-up but no coronal preparation were taken as a negative control group. Microleakage was evaluated using a fluid filtration system. The bonding interface was observed by scanning electronic microscope (SEM).</p><p><b>RESULTS</b>The microleakage was significantly increased after coronal preparation with high-speed handpiece. The negative control group has less leakage [(1.50 × 10(-6) ± 0.37 × 10(-6)) µl×min(-1)×Pa(-1)] than the groups with coronal preparation (P < 0.05); Group 1 leaked significantly more [(6.02 × 10(-5) ± 1.02 × 10(-5)) µl×min(-1)×Pa(-1)] than group 2 [(1.50 × 10(-5) ± 0.26 × 10(-5)) µl·min(-1)×Pa(-1)] and group 3 [(1.50 × 10(-5) ± 0.39 × 10(-5)) µl×min(-1)×Pa(-1)] did (P < 0.05). Corresponding to microleakage, the micro gaps between the resin cement and dentine in group 1 were wider than those in the other groups. The coronal section was wider than the apical part.</p><p><b>CONCLUSIONS</b>High-speed handpiece had negative effects on microleakage of fiber post and core systems. Coronal preparation should be performed 15 min or more after post cementation.</p>

Effect of crestal rotated flap on esthetics of peri-implant soft tissues in anterior maxilla / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the height of interdental papillae around single-tooth implants in the anterior maxillae after exposure of implant using crestal rotated flap.</p><p><b>METHODS</b>The study comprised 34 implants in the anterior maxillae from 32 patients. All implants were uncovered by use of crestal rotated flap technique. Impressions were taken before and after stage 2 surgery, and stone models were used to evaluate the change of papillae height. The gingival papillae index around single-tooth implants was compared before and after the surgery.</p><p><b>RESULTS</b>The average increase in papillae height was (0.77 +/- 0.25) mm, which was statistically significant with analysis of a paired t test (P < 0.05). The change of gingival papillae index showed no significant difference using statistical analysis of rank sum test (P > 0.05). The lower the gingival papillae index was before the surgery, the less the papillae height increased after the surgery.</p><p><b>CONCLUSIONS</b>The main advantages of the crestal rotated flap technique are simplicity and predictability, and it consistently provides high papillae for the maxillary implants.</p>

Effect of two different desensitizers on bond strength of dentin bonding agents / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the bond strength of total-etch or self-etch dentin bonding agents after using two different dentin desensitizers on exposed dentin and investigate the bond interface by scanning electron microscope (SEM).</p><p><b>METHODS</b>Thirty intact and non-carious human third molars were used. The occlusal enamel was removed with the use of a slow-speed saw under water cooling. These teeth were divided into three groups using a table of random numbers with 10 teeth each. These three groups were treated with water (Group C), UltraEZ (Group U) and MI Paste (Group M) respectively. Then 10 teeth from each group were divided into A subgroup (n = 5) bonded with Single Bond 2 adhesive system and B subgroup (n = 5) bonded with Xeno III adhesive system according to manufacturers' instructions. A block of composite resin was build up to 4-5 mm. All the teeth were sectioned occluso-gingivally to obtain bar-shaped specimens with bonded surface area about 0.9 mm x 0.9 mm. The tension of the sample was tested by a microtensile tester at 1 mm/min. The mean values of bond strength were compared using one-way ANOVA. Three samples were chosen randomly from each of six groups for SEM investigation.</p><p><b>RESULTS</b>There were no significant differences between Group U and Group C both in A and B subgroups. While there were significant differences between Group M and Group C in two bonding-agent subgroups. For SEM, the hybrid layer was thin and dense in six groups. Both total-etch and self-etch bonding systems could get fair resin tag infiltration in Group C and Group U. In Group M, the resin tags were relatively shorter and fewer than the anterior mentioned two groups.</p><p><b>CONCLUSIONS</b>UltraEZ had no effect on bond strength of both kinds of dentin bonding agents, while MI paste could diminish bond strength.</p>

Construction and identification of recombinant human platelet-derived growth factor-B adenoviral vector and transfection into periodontal ligament stem cells / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To construct a recombinant human platelet-derived growth factor-B (PDGF-B) adenoviral vector and to transfect it into human periodontal ligament stem cells (PDLSC).</p><p><b>METHODS</b>The recombinant plasmid pAd-PDGF-B was constructed by homologous recombination and confirmed by restriction endonucleases digestion. Recombinant adenovirus was packaged in HEK293 cells. PDLSC were transfected with recombinant adenovirus and PDGF-B expression was confirmed. Expression of collagen type I gene was determined by quantitative analysis of the products of RT-PCR. The cell proliferation was determined with MTT colorimetric assay.</p><p><b>RESULTS</b>The recombinant plasmid pAd-PDGF-B was confirmed by restriction endonucleases digestion. EGFP expression was observed on the third day after transfecting, and the expression of PDGF-B was detected. Immunohistochemical methods revealed that PDGF-B was expressed in PDLSC. Levels of expression of collagen type I gene were increased significantly by transfer of the exogenous PDGF-B gene to PDLSC. At the same time, findings indicated that Ad-PDGF-B stimulated PDLSC proliferation. MTT assay indicated the absorbance of PDLSC by stimulating with Ad-PDGF-B was (0.68 +/- 0.02), P < 0.01.</p><p><b>CONCLUSIONS</b>Using the AdEasy system, the human PDGF-B recombinant adenovirus can be rapidly obtained. These results indicate that recombinant adenoviruses encoding PDGF-B transgenes could modulate proliferative activity of PDLSC, enhance the high expression of collagen type I and lay the foundation for periodontal tissue regeneration and dental implant gene therapy.</p>

Clinical evaluation and comparison of porcelain laminate veneers and computer aided design and computer aided manufacture veneers / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the clinical application of a computer aided design and computer aided manufacture (CAD/CAM) veneer system.</p><p><b>METHODS</b>Sixty-five CAD/CAM veneers were made for 23 patients and 105 porcelain veneers were made for 25 patients. After three years, the clinical performance of two veneer systems were evaluated and compared according to modified California Dental Association/Ryge criteria. The clinical success rate and patient satisfactory rate were calculated.</p><p><b>RESULTS</b>The success rates of porcelain veneer and CAD/CAM veneer were 96.2% and 93.8%, respectively. The patient satisfactory rates were 92.4% and 90.8%. There was no significant difference between two veneer systems in color match, marginal discoloration and marginal fit. But the surface texture of CAD/CAM veneers was better than that of porcelain veneers.</p><p><b>CONCLUSIONS</b>CAD/CAM veneer system was a successful approach for veneer restorations.</p>

An experimental study on alveolar ridge preservation prior to dental implant placement / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the combination of surgical grade calcium sulfate hemihydrate (SGCS) and platelet-rich plasma (PRP) for alveolar ridge preservation prior to implant placement.</p><p><b>METHODS</b>Changes of bone quantity and quality in extraction sites following the SGCS/PRP and SGCS implantations were investigated by spiral computer tomography scan, bone scintigraphy, radiographic, histological and histomorphometric examinations.</p><p><b>RESULTS</b>The placement of SGCS/PRP reduced the resorption of the alveolar ridge. It also promoted bone metabolism and bone-to-implant contact. The addition of PRP to SGCS achieved the enhancement of the bone metabolism only at the early healing phase.</p><p><b>CONCLUSIONS</b>In this animal experiment, SGCS/PRP may be used as fresh extraction sockets graft for alveolar ridge preservation prior to implant placement.</p>

Chondrogenic differentiation of adult human periodontal ligament stem cells in vitro / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To isolate and cultivate human periodontal ligament stem cells (PDLSC) and to investigate the feasibility of PDLSC in vitro differentiation into chondrogenic phenotype.</p><p><b>METHODS</b>Periodontal tissue was obtained from healthy young human teeth extracted for orthodontic purposes. PDLSCs were isolated by single-colony selection and cultivated. PDLSC of passage 3 was plated at density of 1 x 10(7) cells/cm3 and induced with chondrogenic induction medium of DMEM containing TGF-beta1 (10 microg/L), IGF-1 (50 microg/L), dexamethasone (40 microg/L) and 10% FBS. In control group, the constructs were maintained in DMEM medium + 10% FBS. After 21 days induction, the results were evaluated by histology, histochemistry, immunohistochemistry and RT-PCR.</p><p><b>RESULTS</b>The constructs in experimental group were smooth and relatively firm in texture after 3 weeks of culture. Toluidine blue staining showed the formation of distinct lacuna structure. Positive staining of type II collagen was also detected by immunohistochemistry and it was confirmed by RT-PCR. In contrast, in the control group, the constructs collapsed gradually, lacuna was barely detected in histology and type II collagen expression negative.</p><p><b>CONCLUSIONS</b>Periodontal ligament contain stem cells can be isolated and cultivated. PDLSC have the potential of chondrogenic differentiation.</p>

Microtensile bond strength and morphological evaluations of total-etch and self-etch adhesives to caries-affected dentin / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the microtensile bond strength and bond interface of total-etch or self-etch adhesives to normal dentin and caries-affected dentin.</p><p><b>METHODS</b>A total of 20 molars with occlusal caries lesion were used. The caries-affected dentin was obtained by removing the caries-infected dentin under the guidance of the caries detector. Beyond the level of caries-affected dentin all the enamel and partial dentin were removed. The adhesive systems, two total-etch adhesives (All-Bond 2, Prime&Bond NT) and two self-etch adhesives (Clearfil SE Bond, Xeno III) were applied respectively under the instructions of manufacturers. A block of composite resin was build up superficially. All the teeth were sectioned to obtain bar-shaped specimens with bonded surface area about 0.9 mm x 0.9 mm. The specimens were divided into normal dentin group and caries-affected dentin group via stereomicroscope. The bond strength was tested in a microtensile tester with a crosshead speed of 1 mm/min. The mean values of bond strength were compared using two-way ANOVA. The bonding interface between the dentin and adhesives was qualitatively evaluated under the observation of scanning electron microscope (SEM).</p><p><b>RESULTS</b>Two-way ANOVA revealed a significant influence of both the type of dentin and the adhesive systems tested on microtensile bond strength values. All the adhesives attained higher strength in normal dentin. In normal dentin, there was no significant difference between total-etch and self-etch adhesives. In caries-affected dentin, bond strength of Xeno III was significantly lower than the others. For SEM, the hybrid layer in caries-affected dentin was thicker but more porous than that in normal dentin. Compared with normal dentin, there was fewer resin tag exhibited in caries-affected dentin and no lateral branches were observed.</p><p><b>CONCLUSIONS</b>The total-etch adhesive had higher bond strength than self-etch adhesive systems in caries-affected dentin.</p>

Effects of residual water on microtensile bond strength of one-bottle dentin adhesive systems with different solvent bases / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The wet-bonding technique is recommended for the one-bottle dentin adhesive systems, but the moisture concept varies widely among the instructions of manufacturers as well as among investigators. The aim of this study was to evaluate the effects of different dentin surface moisture on the microtensile bond strength(s) of an ethanol/water-based adhesive system and an acetone-based system to dentin.</p><p><b>METHODS</b>Forty intact human premolars extracted for orthodontic reasons were used. Superficial occlusal flat dentin surfaces of these premolars were exposed, finished with wet 600-grit silicon carbide paper. Under four wet and dry conditions (overwet, blot dry, one-second dry and desiccated), resin composite was bonded to dentin by using Single Bond (SB) or Prime & Bond NT (PB) according to the manufacturers' instructions. The teeth were longitudinally sectioned in the "x" and "y" directions to obtain bonded beams with a cross-sectional area of 0.81 mm(2) with a slow-speed diamond saw. The bonded specimens were tested in tension at a crosshead speed of 1 mm/min until failure of the bonds. Failure modes were observed with a scanning electron microscope. The mean bond strengths were analyzed by one-way ANOVA and Turkey's test.</p><p><b>RESULTS</b>The bond strength of the overwet/SB, blot dry/SB, one-second dry/SB and desiccated/SB groups was 10.87 MPa, 22.47 MPa, 24.91 MPa and 12.99 MPa, respectively. The bond strength of the overwet/PB, blot dry/PB, one-second dry/PB and desiccated/PB groups was 10.02 MPa, 20.67 MPa, 21.82 MPa and 10.09 MPa, respectively. For both SB and PB, the blot dry group and one-second dry group revealed significantly higher bond strengths than the overwet and desiccated groups (P < 0.05).</p><p><b>CONCLUSIONS</b>In order to achieve the highest bond strength to dentin, keeping the dentin surface in an appropriately moist condition is critical for the one-bottle dentin adhesive systems with ethanol/water or acetone solvent.</p>

Microtensile bond strengths of three dentin adhesive systems / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate in vitro the microtensile bond strengths of three dentin adhesive systems and their respective fracture modes.</p><p><b>METHODS</b>A total of 15 intact young human premolars extracted for orthodontic reasons were used. The enamel of occlusal surfaces of these premolar teeth was removed and superficial dentine was exposed, finished with wet 600-grit silicon carbide paper. And then these teeth were randomly divided into three groups. A block of composite resin was bonded respectively with three dentin adhesive systems: All-bond 2 (Group AB(2)), Fluoro-Bond (Group FB) and Xeno III (Group Xeno) according to manufacturers' instructions. The bonded teeth were kept in distilled water for 24 h at 37 degrees C. The roots were removed from the remaining crown approximately 1 - 2 mm below the cemento-enamel junction with a slow-speed diamond saw. The teeth were sectioned to obtain bar-shaped specimens, whose bonded surface areas were about 0.8 mm(2). The specimens were stressed at a crosshead speed of 1 mm/min until rupture of the bond. SEM was used to observe the fracture modes. The mean bond strengths were compared using one-way ANOVA and LSD tests. The frequency of fracture modes was compared using Krukal-Wallis and Mann-Whitney U-test.</p><p><b>RESULTS</b>Mean microtensile bond strengths were (29.56 +/- 5.47) MPa for Group AB(2), (15.81 +/- 7.67) MPa for Group Xeno, and (14.61 +/- 4.50) MPa for Group FB. The bond strength of Group AB(2) was greater than those of the other two groups (P < 0.01). The bond strengths of Group Xeno and Group FB were not significantly different. SEM examination indicated that the adhesive failure was the most mode of fracture.</p><p><b>CONCLUSIONS</b>The microtensil bond strengths of three dentin adhesive systems to normal human dentine were different and the total-etching adhesive All-Bond 2 exhibited the greatest bond strength. It was recommended that dentin adhesive agent should be used according to clinical situation.</p>

In vitro cytotoxicity evaluation of comfort denture adhesive / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to evaluate the in vitro cytotoxicity of novel Comfort denture adhesive (Comfort-DA), which was developed by the authors, to human oral fibroblasts (HOFs).</p><p><b>METHODS</b>A sample of Comfort-DA was prepared and extracted in culturing medium to prepare the eluate. Then the eluate was diluted by culturing medium to 50% and 75% concentration for the assessment of cytotoxicity by tetrazolium bromide (MTT) colorimetric assay. Wells containing fresh medium alone were served as control. Cell viability was recorded by optical density after culturing in an atmosphere of 5% CO2 and 95% air at 37 degrees C for 2, 3 and 4 days, respectively. The viability of HOF cells was evaluated by MTT assay to investigate cell proliferation. Optical density (OD) was measured by a spectrophotometer at 490 nm. Then evaluating the cytotoxicity grade in test groups according to the means of cell proliferation. ANOVA was used to test the statistical significance.</p><p><b>RESULTS</b>The statistical analysis of the results of MTT cytological assay indicated significant difference (P < 0.05) in OD (indicate cell viability) between all concentrations of Comfort-DA and the control at all incubation times. The results of cell proliferation percentage also showed that the cytotoxicity grade of tested material only displayed "0-2".</p><p><b>CONCLUSION</b>The generally favorable in vitro cytotoxicity of the Comfort-DA formulations indicates that this product may be an efficacious denture adhesive.</p>

A preliminary study on the color effect of IPS Empress all-ceramic veneers / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the opaquing capacity, color compatibility and stability of IPS Empress all-ceramic veneers.</p><p><b>METHODS</b>A total of 86 IPS Empress all-ceramic veneers were made for 18 patients. The patients were divided into three groups: Group A was tetracycline teeth, 64 veneers for 5 patients; Group B was non-tetracycline teeth, 22 veneers for 13 patients; Group C was 22 natural vital teeth with normal color as control group. Before and after veneers were inserted, ShadeEye NCC was employed to obtain L * a * b * values of each tooth. The values of cemented veneers used as the baseline, the L * a * b * values of each veneer were measured half a year, 1 year, and 2 years after restoration respectively. All L * a * b * values at different evaluation times were analyzed by SPSS 10.0.</p><p><b>RESULTS</b>Before and after veneers were restored, the L * a * b * values of both Group A and Group B were significantly different, the color difference being 5.01 and 4.15 respectively. The color difference between Group A and selected shade guides was 2.45. Compared with the baseline value, the L * value of Group A significantly decreased 2 years after restoration, but the DeltaE of different evaluation times was not significantly different. The color difference between Group B and Group C was 0.22 and there was no significant color difference after restoration.</p><p><b>CONCLUSIONS</b>IPS Empress all-ceramic veneers have excellent opaquing capacity, color compatibility and stability to non-tetracycline teeth. To tetracycline teeth IPS Empress all-ceramic veneers have a certain opaquing capacity, but they cannot completely match with shade guides; the L * value is significantly different after restoration and further studies are needed to evaluate its color effect.</p>

Orthodontic extrusion of crown-root fractured teeth and teeth with root caries--report of 5 cases / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To discuss orthodontic extrusion of crown-root fractured teeth before restoration.</p><p><b>METHODS</b>3 cases with fractured teeth and 2 cases with root caries were performed canal therapy.</p><p><b>RESULTS</b>Orthodontic extrusion of the root was carried out before restoration. All cases were satisfactory after treatment.</p><p><b>CONCLUSIONS</b>Orthodontic extrusion of remaining root before restoration not only can maintain the remaining root but also obtain functional and esthetic results.</p>

Study on elastic limit and relevant enclasp force of non-precious metal casting clasp / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the elastic limit and relevant enclasp force of the non-precious metal casting clasp.</p><p><b>METHODS</b>Casting clasp samples of five cobalt-chromium alloys and one 18 - 8 nickel-chromium alloy were made from prefabricated clasp wax by invesing, casting, sandblasting, and ultrasonic cleaning. The process of casting clasp samples deflected by loading and returned by unloading was tested and electric signals were collected by an omnipotent material machine. The analog electric signal was converted to digital signal by an analog to digital converter and stored in a computer. The elastic limit and the relevant enclasp force were analyzed using a relative software.</p><p><b>RESULTS</b>The elastic limit and the relevant enclasp force of the casting clasp made from the 18 - 8 nickel-chromium alloy were smallest and those of the clasps made from the cobalt-chromium alloys in various brands were different. The range of the elastic limit of the cobalt-chromium alloy casting clasp with the length of 5.0 mm in undercut was 0.28 mm-0.33 mm and the relevant enclasp force was 14.42 g-19.28 g.</p><p><b>CONCLUSIONS</b>In clinic, we should select the suitable undercut deepness wherein the cobalt-chromium alloy casting clasps, according to different brands of the casting alloy, undercut length, undercut slope, and the clasp thickness.</p>