[Experimental study on the optical properties of different-translucency zirconia-ceramic restorations].

PURPOSE: The purpose of this in vitro study was to measure the color difference(△E) on titanium alloy background and translucency parameter(TP) of four kinds of zirconia-based all-ceramic specimens, providing a clinical reference for restoring grayish abutment. METHODS: Four groups with a total of 24 ceramic specimens were fabricated to a final specimen dimension of 14 mm×14 mm×1.5 mm, two kinds of zirconia with different translucency（Beitefu high-translucency, Cercon low-translucency）and their corresponding body porcelain at the shade of A2 were used as followed:high-translucency zirconia sintered dentine porcelain(Group A),low-translucency zirconia sintered dentine porcelain(Group B),high-translucency zirconia sintered opaque and dentine porcelain(Group C),low-translucency zirconia sintered opaque and dentine porcelain(Group D).The color parameters of the specimens under two backgrounds (titanium alloy and shade A3 light-activated resin-based composite) were measured by Shade Eye NCC colorimeter, then the △E value was determined by the relevant equations. The color parameters under black and white background were measured, and TP value was calculated. The experimental data were analyzed with SPSS 17.0 software package. RESULTS: There was significant difference of the TP value and the △E value among four groups specimens(P＜0.05), the TP value was arranged as follows: group D＜group C＜group B＜group A. The specimen used with opaque porcelain showed significantly reduced translucency. The △E value was arranged as follows: group D ＜ group C ＜ group B ＜ 1.5 ＜ 2 ＜group A, the △E value of group A cannot be accepted in clinic. CONCLUSIONS: The restoration of low-translucency zirconia sintered translucency veneering ceramic has better translucency, with value of △E＜1.5 when used on the grayish abutment, which has a good aesthetic performance.

Involvement of RUVBL1 in WNT/ß-Catenin Signaling in Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor of head and neck squamous cell carcinoma (HNSCC), but the causes and molecular mechanisms remain unclear. The wingless-integrated/ß-catenin (WNT/ß-catenin) signaling pathway plays a vital role in cancer cell proliferation, differentiation, and metastasis, including OSCC. To screen potential ß-catenin-associated genes involved in OSCC, the intersection of these genes in the STRING and IMEx databases was assessed using differential expression genes (DEG) from public microarrays, and 22 were further selected to construct a ß-catenin-protein interaction network. The top 14 hub genes (node degree > 10) within the network were selected. Pearson's correlation analysis showed that ß-catenin expression correlated positively with the expression of 11 genes, including AR, BIRC5, CDK6, DKK1, GSK3B, MET, MITF, PARD3, RUVBL1, SLC9A3R1, and SMAD7. A heat map of overall hub gene survival was created, and elevated expression of DKK1 and RUVBL1 was associated with poor survival using the Mantel-Cox test. To identify the function of RUVBL1, colony formation assay, transwell assay, and western blotting revealed that knock-down of RUVBL1 by siRNA decreased H157 and Cal-27 cell proliferation and metastasis by inhibiting ß-catenin signaling. These findings suggest that RUVBL1 may serve as a diagnostic and prognostic biomarker for OSCC, as well as a therapeutic target, and may help to uncover additional molecular mechanisms of ß-catenin-driven OSCC tumorigenesis.

Overexpression of DEL-1 Downregulates SH3BP2 Expression and Inhibits Porphyromonas gingivalis-induced Gingival Inflammation In Vivo and In Vitro.

PURPOSE: The role of developmental endothelial locus-1 (DEL-1) in Porphyromonas gingivalis (P. gingivalis)-induced periodontitis and the related molecular mechanisms are unclear. This study aimed to investigate the effect of DEL-1 on SH3 Domain Binding Protein 2 (SH3BP2) expression, and to explore the regulatory role of DEL-1 in periodontal inflammation. MATERIALS AND METHODS: We constructed a P. gingivalis-induced rat experimental periodontitis model, and cultured P. gingivalis-stimulated THP-1 cells in vitro. THP-1 cell viability and cell cycle were examined by CCK-8 and flow cytometry. Rat gingival tissues were collected for hematoxylin-eosin staining. The expression of SH3BP2 and nicotinamide phosphoribosyltransferase (NAMPT) was examined using Western blot. RESULTS: We found that the proliferation of P. gingivalis-infected THP-1 cells was increased by DEL-1. DEL-1 inhibited the expression of NAMPT and SH3BP2 in gingiva tissues of rats with periodontitis as well as in P. gingivalis-infected THP-1 cells. CONCLUSIONS: Overexpression of DEL-1 downregulated SH3BP2 expression and reduced gingival inflammation induced by P. gingivalis. DEL-1 presents some regulatory effects on gingival inflammation in a P. gingivalis-induced rat experimental periodontitis model, suggesting the therapeutic potential of DEL-1 in regulating periodontal inflammation.

Self-swelling tissue expander for soft tissue reconstruction in the craniofacial region: An in vitro and in vivo evaluation.

BACKGROUND: Craniofacial soft-tissue defects mostly have an impact on the treatment of various oral diseases. Tissue expander is an important technique for tissue reconstruction, especially for soft tissues in reconstructive surgery. OBJECTIVE: This research aimed to develop a new self-swelling tissue expander, namely hydrogel, for soft tissue reconstruction in craniofacial region. METHODS: In vitro, the chemical and physical characteristics of hydrogel were evaluated by SEM, swelling rate, mechanical testing, EDS, and FT-IR. In vivo, the craniofacial implant model of SD rats were divided into group A as control, group B with hydrogels for 1 week expansion, group C for 2 weeks and group D for 4 weeks (n = 5), and the effects were analyzed by HE staining, histological and radiographic evaluation. RESULTS: The in vitro results suggested that dry hydrogel possessed a uniform surface with micropores, the surface of post-swelling hydrogel formed three-dimensional meshwork. Within 24 hours, hydrogels expanded markedly, then slowed down. The mechanical property of hydrogels with longer expansion was better, whose main elements were carbon and oxygen. FT-IR also verified its molecular structure. In vivo, the wounds of rats recovered well, hydrogels could be removed as one whole piece with original shape and examined by radiographic evaluation, besides, the expanded skin and developed fibrous capsule formed surrounding hydrogels. CONCLUSION: The new expander was designed successfully with good chemical and physical characteristics, and could be applied in an animal model to help tissue reconstruction.

Altered Intrinsic Brain Activity in Patients With Toothache Using the Percent Amplitude of a Fluctuation Method: A Resting-State fMRI Study.

Objective: The percent amplitude of fluctuation (PerAF) technique was utilized to evaluate the neural functions of specific cerebrum areas in patients with toothache (TA). Patients and Methods: An aggregation of 18 patients with TA (eight males and 10 females) were included in the study. We also recruited 18 healthy controls (HCs; eight men and 10 women) aligned for sex and age. Resting functional magnetic resonance imaging (rs-fMRI) scans were obtained. Then, we utilized the PerAF method and a support vector machine (SVM) to analyze the image data and measure neural abnormalities in related cerebrum areas. Receiver operating characteristic (ROC) curve analysis was utilized to appraise the two data sets. Results: The PerAF signals in the right dorsolateral superior frontal gyrus (RDSFG) and the right posterior central gyrus (RPCG) of TA sufferers were lower than HC signals. These results may reveal neural dysfunctions in relevant cerebrum regions. The AUC values of PerAF in the two areas were 0.979 in the RDSFG and 0.979 in the RPCG. The SVM results suggested that PerAF could be utilized to distinguish the TA group from HCs with a sensitivity of 75.00%, a specificity of 66.67%, and an accuracy of 70.83%. Conclusion: Patients with TA had marked differences in PerAF values in some regions of the cerebrum. Changes in PerAF values represented distinctions in blood oxygen level dependent semaphore intensity, which reflected the overactivity or inactivation of some cerebrum areas in those suffering from TA. At the same time, we analyzed the PerAF values of TAs with ROC curve, which can be helpful for the diagnosis of TA severity and subsequent treatment. Our results may help to elucidate the pathological mechanism of TA.

Chlorogenic Acid Promotes Osteogenic Differentiation of Human Dental Pulp Stem Cells Through Wnt Signaling.

Periodontal disease (PD) is one of the main causes of periodontal bone resorption and tooth loss in adults. How to repair the alveolar bone effectively has always been a challenge. This study was designed to clarify the effects and the underlying molecular mechanisms of chlorogenic acid (CGA) on osteogenic differentiation of human dental pulp stem cells (hDPSCs). In this study, we used CGA to treat hDPSCs. The osteogenic experiment showed that CGA can promote hDPSCs osteogenic differentiation. RNA-Seq and quantitative real-time polymerase chain reaction showed that CGA treatment enhanced the expression of the osteogenesis genes for frizzled-related protein (FRZB) and pyruvate dehydrogenase kinase 4 (PDK4) and inhibit the expression of the osteoclastogenesis genes such as those for asporin (ASPN) and cytokine-like 1 (CYTL1). Western blot analysis showed that besides FRZB, CGA treatment also caused reduction of both active and total ß-catenin, while increased the total calcium/calmodulin-dependent kinase II (CamKII), the phosphorylated CamKII (pCamKII) and the phosphorylated cAMP-response element-binding protein (pCREB). Likely, the increased osteogenesis was associated with reduced canonical Wnt/ß-catenin signaling but increased noncanonical Wnt/Ca2+ signaling. The results suggested that CGA can promote the osteogenic differentiation of hDPSCs by regulating Wnt signaling. These findings will serve as a foundation for further studies on how to repair defective alveolar bone for the patients with PD.

Surface modification of carbon nanotube with gelatin via mussel inspired method.

Carbon nanotube (CNT) has aroused much attention in biomedical field. However, the cytotoxicity and aggregation are critical factors that affect the application of carbon nanotube (CNT). Herein, gelatin was grafted on the surface of CNT via mussel-inspired method. The gelatin modified CNT can disperse homogeneously in water. The in vitro test showed that gelatin modified CNT showed much better biocompatibility than the native CNT, which may improve its potential application in biomedical field.

Effect of micropore/microsphere topography and a silicon-incorporating modified titanium plate surface on the adhesion and osteogenic differentiation of BMSCs.

Good biological properties for titanium implants will shorten the treatment cycle and improve patient comfort, which are also the main goals of dentistry and orthopaedics. At present, the biological properties of titanium implants are mainly enhanced in two aspects: their surface chemistry and surface morphology. In this study, a surface modification strategy combining bioactive trace elements with surface micromorphology modification was used to enhance the biological properties of pure titanium. A new coating incorporating silicon micropore/microsphere topography was prepared on a titanium plate by micro-arc oxidation (MAO) technology. The properties of the coating and its effects on the adhesion and osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) were further analyzed. The experimental results show that a coating doped with amorphous silicon with micropore/microsphere topography was incorporated onto the titanium surface and the surface roughness in the treated groups was obviously higher than that in the Ti group. In vitro, the presence of a silicon-incorporating coating with a micropore/microsphere topography on the titanium surface significantly enhanced the initial adhesion, proliferation and osteogenic differentiation of BMSCs. These results indicate that the silicon-incorporating coating with micropore/microsphere topography has potential applications in dentistry and orthopaedics.

Antibacterial Properties of Bilayer Biomimetic Nano-ZnO for Dental Implants.

Dental implant surgery has a relatively high incidence of peri-implantitis. In this research, ZnO nanorods and ZnO nanospheres were synthesized by a hydrothermal method. ZnO nanorods first covered the surface of Ti or Ti-Zr, and ZnO nanospheres were then modified as the outermost layer. By these means a dual antibacterial effect could be realized by the rapid release of ZnO nanospheres and the sustained release of ZnO nanorods. Subsequent studies implied that this ZnO nanorods-nanospheres hierarchical structure (NRS) could be stably loaded on the surface of roughened Ti and Ti-Zr slices. The modified materials not only showed excellent antibacterial activities against both Escherichia coli and Staphylococcus aureus but also showed low cellular cytotoxicity. This ZnO NRS structure is thus expected to be used as a general antimicrobial coating on the surface of Ti (Ti-Zr) in dental implant surgery.

[Effect of different sandblasting conditions on the metal-ceramic bonding strength of Co-Cr alloy fabricated by selective laser melting technology].

OBJECTIVE: To investigate the effect of different sandblasting conditions on the metal-ceramic bonding strength of Co-Cr alloy fabricated by selective laser melting (SLM) technology. METHODS: A total of 63 specimens of Co-Cr alloy fabricated by SLM were prepared and randomly divided into nine groups (n=7). Each group was treated with different powder particles (A1=50 µm, A2=100 µm, and A3=150 µm) and pressures (B1=0.2 MPa, B2=0.4 MPa, and B3=0.6 MPa) in sandblasting. One sample was randomly selected from each group for microstructure observation by scanning electron microscope (SEM). Ceramic was fired at the center of the specimens. Metal-ceramic bonding strength was measured with universal testing machine. Results were statistically analyzed with SPSS 17.0 software. RESULTS: The mean bond strengths were as follows: Group A1B1: 27.22 MPa±0.95 MPa, Group A1B2: 27.58 MPa±0.47 MPa, Group A1B3: 26.80 MPa±0.71 MPa, Group A2B1: 27.54 MPa±0.78 MPa, Group A2B2: 30.75 MPa±0.43 MPa, Group A2B3: 26.93 MPa±0.88 MPa, Group A3B1: 28.18 MPa±0.93 MPa, Group A3B2: 29.55 MPa±0.57 MPa, and Group A3B3: 28.11 MPa±0.91 MPa. The particle factor of Al2O3 and the pressure factor of blasting showed statistical significance (P<0.05). An interaction was observed between the factors of particle and pressure (P<0.05). Mixed fracture mode of all specimens was observed after the shear strength test. CONCLUSIONS: In conclusion, metal-ceramic bonding strength reaches the maximum when specimens are sandblasted with 100 µm alumina oxide at 0.4 MPa pressure.

Impact of Dentinal Tubule Orientation on Dentin Bond Strength.

This study aimed to determine the impact of dentinal tubule orientation on dentin bond strength to provide a reference for clinical cavity preparation in resin-bonded restoration. Patients aged 13-16 years were selected, including 18 males and 21 females. Forty-eight human maxillary first premolars from orthodontic extractions were chosen to prepare the test models with the dentinal tubule orientations perpendicular and parallel to the bonding substrate. The test models in the vertical and parallel groups were divided into three groups: total-etching with 20% phosphoric acid, total-etching with 35% phosphoric acid and self-etching, with the dentinal tubule surfaces bonded with composite resin blocks in each group. After the standard test models of dentinal tubule-composite resin blocks were placed in distilled water and stored at 37°C for 24 h, shearing tests were performed using a universal material testing machine at a crosshead speed of 0.5 mm/min. The bond strength values in the vertical group were 19.33±1.59 MPa for the 20% phosphoric acid group, 21.39±2.34 MPa for the 35% phosphoric acid group, and 16.88±1.54 MPa for the self-etching group. The bond strength values in the parallel group were 24.53±1.99 MPa for the 20% phosphoric acid group, 25.16±2.88 MPa for the 35% phosphoric acid group, and 20.83±1.99 for the self-etching group. After using same total-etching adhesive, the shear bond strength of the parallel group was higher than that of the vertical group, and the difference was statistically significant (P<0.05). Regardless of vertical group or parallel group, the difference in the bond strength value between the total-etching groups and the self-etching group was statistically significant (P<0.05). It was concluded that the dentin bonding substrate which was parallel to the direction of the dentin tubule achieved an improved bond strength; the total-etching adhesives achieved higher bond strengths in dentin bond than the self-etching adhesives.

[Experimental research of hot alkaline solution etching treatment on zirconia/resin bonding strength].

PURPOSE: In this experiment, we applied hot alkaline solution (20%NaOH solutions) to treat the surfaces of zirconia ceramics in vitro, then evaluated the changes of bond strength of zirconia ceramics and resin cement. METHODS: Eighteen pieces of zirconia ceramic specimens were made, using the same method of grinding and polishing, and then randomly divided them into 3 groups: group A with hot alkali solution treatment (20%NaOH) (n=6), group B underwent sand blasting with a diameter of 110 ?m alumina particles (n=6), group C was as the control group. Atomic force microscope was used to measure the roughness of the surface of the specimens, and the zirconia surfaces were scanned to get topography maps, then made them into ceramic/resin-bonded specimens. After 24 h of water reservoir processing, shearing bonding strength (SBS) test was conducted and their bond interfaces were observed to investigate the lesions of different degree in these specimens. The data were analyzed with SPSS20.0 software package. RESULTS: Surface roughness was group B> group A > group C, SBS was group B>group A>group C. CONCLUSIONS: Under the condition of 180degrees centigrade, bonding strength between zirconia and resin cement after treatment with 20% NaOH solution was significantly higher than without any treatment, but lower than sand blasting treatment.

[Evaluation of the effect of modified wet particle erosion on bond strength between 3Y-TZP zirconia framework and veneering porcelain].

PURPOSE: To evaluate the effect of bond strength between 3mol% yttrium-stabilized tetragonal zirconium polycrystal (3Y-TZP) zirconia framework after modified wet particle erosion and veneering porcelain. METHODS: A total of 174 [8 mm× 8 mm× 3 mm (±0.02)] specimens were prepared and then randomly divided into different groups according to different particle size, sandblasting pressure, sandblasting time through conventional sandblasting (experimental groups); specimens in the control group were not sandblasted. The bond strength between 3Y-TZP zirconia framework and veneering porcelain was measured using a universal testing machine. Statistical analysis was performed using SPSS17.0 software package. The bond strength of specimens treated by two methods-conventional sandblasting and modified wet particle erosion under the same condition (150 µm, 0.6 MPa, 30 s) were acquired, while the surface was analyzed microscopically before the specimens were veneered with the veneering ceramic under scanning electronic microscope (SEM). RESULTS: The bond strength of conventional sandblasting group under the condition (110 µm, 0.4 MPa,30 s) was maximal, and significantly higher than the control group (P<0.05). The bond strength of modified wet particle erosion group was significantly higher than the conventional sandblasting group and control group (P<0.01); SEM showed that the surface of specimen with modified wet particle erosion was homogeneously rough; the surface specimen with conventional sandblasting was heterogeneously rough, some microcracks were seen in some areas. CONCLUSIONS: Sandblasting can slightly enhance the bond strength between 3Y-TZP zirconia framework and veneering porcelain, modified wet particle erosion is recommended for 3Y-TZP zirconia framework surface treatment.

[The influence of lower vertical dimension construction of complete denture on cerebral blood flow].

PURPOSE: To investigate the influence of lower vertical dimension construction on cerebral blood flow among patients with complete denture. METHODS: Ten edentulous patients were chosen and lower vertical dimension was constructed with complete denture. Transcranial Doppler ultrasonography was used to detect the average peak flow velocity, peak systolic velocity and end-diastolic peak flow velocity of the middle cerebral artery. The detection was performed before chewing, 10 minutes after chewing and 20 minutes after chewing, respectively. Before-after self control study was designed, and SPSS18.0 software package was used to analyze the data with independent samples t test and multiple comparisons and analysis of variance. RESULTS: There was no significant increase in cerebral blood flow before chewing, 10 minutes after chewing and 20 minutes after chewing in the experimental group, while blood flow velocity of the control group was significantly increased. The blood flow velocity of the experimental group 10 minutes after chewing was significantly lower than that of the control group, while no significant difference was found after chewing between the experimental group and control group 20 minutes. CONCLUSIONS: No significant increase of cerebral blood flow is detected in patients whose vertical dimension are lower when restored with complete denture during mastication.

[Evaluation of bond strength between low fusing porcelain with goldplated cobalt-chromium alloys].

PURPOSE: To evaluate the bond strength of Vita OMEGA 900 low fusing porcelain fused with the goldplated Wirobond cobalt-chrome metalt ceramic alloy. METHODS: Low fusing porcelain was fused with the cobalt-chromium alloy strips(group A) and the goldplated cobalt-chromium alloy strips(group B) respectively according to ISO9693 (A:8,B:10). 8 specimens of each group were submitted to three point bending test. Two more test pieces fused with gold plated cobalt-chromium alloys were made (group B'). One test piece of both group B and group B' were observed under scanning electron microscope (SEM) randomly. The data was analyzed with SPSS 16.0 software package. RESULTS: The bond strength (MPa) of group A and group B was 29.92±4.28 and 28.20±5.21, respectively (P>0.05), both higher than 25 MPa required by ISO9693. SEM showed that Vita OMEGA 900 low fusing porcelain and the goldplated Wirobond cobalt-chrome metalt ceramic alloy combined together closely without cracks. Much gold was fused to the cobalt-chrome alloy surface of breaking porcelain specimen after testing. CONCLUSIONS: Vita OMEGA 900 low fusing porcelain can match with the goldplated Wirobond cobalt-chrome metalt ceramic alloy. Supported by Foundation of Education Department of Jiangxi Province (GJJ10367).

[Finite element stress analysis of all-ceramic continuous crowns of the lower anterior teeth in differential shoulder thickness].

PURPOSE: To investigate the stress distributions under load in 3 types of all-ceramic continuous crowns of the lower anterior teeth with differential shoulder thickness. METHODS: Cone-beam CT (CBCT) was used to scan the in vitro mandibular central incisors, and achieve three-dimensional finite element model of all-ceramic continuous crowns with different shoulder width by using Mimics, Abaqus software. Different load conditions were simulated based on this model to study the effect of shoulder width variation on finite element analysis of 3 kinds of different all-ceramic materials of incisors fixed continuous crowns of the mandibular. RESULTS: Using CBCT, Mimics10.01 software and Abaqus 6.11 software, three-dimensional finite element model of all-ceramic continuous crowns of the mandibular incisor, abutment, periodontal ligament and alveolar bone was established. Different ceramic materials and various shoulder width had minor no impact on the equivalent stress peak of periodontal membrane, as well as alveolar bone. With the same shoulder width and large area of vertical loading of 120 N, the tensile stress was the largest in In-Ceram Alumina, followed by In-Ceram Zirconia and the minimum was IPS.Empress II. Under large area loading of 120 N 45° labially, when the material was IPS.Empress II, with the shoulder width increased, the porcelain plate edge of the maximum tensile stress value increased, while the other 2 materials had no obvious change. CONCLUSIONS: Finite element model has good geometric similarity. In the setting range of this study, when the elastic modulus of ceramic materials is bigger, the tensile stress of the continuous crown is larger. Supported by Research Project of Department of Education, Jiangxi Province (GJJ09130).

[Effects of three different surface treatments on bond strength between composite resin core and glass ionomer cement].

OBJECTIVE: To compare shear bond strength (SBS) between composite resin core (CRC) disposed with three different surface treatments and glass ionomer cement (GIC), so that to provide theoretical basis for luting of crowns to CRC. METHODS: According to three different surface treatments, thirty blocks of CRC were randomly and equally divided into three groups: Roughening with diamond grit bur(RDB), RDB plus etching with Gluma Etch 35 Gel (RDBE), RDB plus coating with Adper Single Bond2 adhensive (RDBA). All CRC were cemented with GIC. All specimens were preserved in 37 degrees C water for 24 h, then SBS tests for eight specimens in each group were performed using a universal testing machine at a constant crosshead speed of 0.5 mm x min(-1). The surface topography of one CRC of each group was observed using field emission scanning electron microscope (FE-SEM) at 100 amplification. The interface between CRC and GIC was observed using FE-SEM at 500 amplification. Then the nature of failure was also recorded using FE-SEM at 25 amplification and the data were analyzed with a Kruskal-Wallis H test. RESULTS: The surface topography of each group and the interface between CRC and GIC observed using FE-SEM were significantly different, but significant differences on the nature of failure between groups were not found (P > 0.10). SBS of each group was (4.28 +/- 0.18) MPa for RDB, (4.65 +/- 0.17) MPa for RDBE, (2.39 +/- 0.21) MPa for RDBA, respectively (P < 0.01). CONCLUSION: The SBS between CRC and GIC is affected by the surface treatments of CRC.

[The effect of H2O2 surface treatment of posts on the bond strength between glass fiber posts and the resin cement].

PURPOSE: To evaluate the effect of H2O2 on the push-out bond strength between glass fiber posts and the resin cement. METHODS: Eighteen Tenax glass fiber posts and 18 Macthpost glass fiber posts were randomly assigned to 6 groups according to the surface treatments. Group A, no surface treatment (control group); Group B, treated with silane agent; Group C, treated with 3% H2O2, then with silane agent; Group D, treated with10% H2O2, then with silane agent; Group E, treated with20% H2O2, then with silane agent; Group F, treated with 30% H2O2, then with silane agent. The posts were adhered using the resin cement to form cylindrical resin block. Each resin block was sectioned to 7 sections of 1 mm thick. A push-out test was performed on other sections of each post to measure bond strengths. The date was recorded and analyzed with SPSS13.0 software package. The failure modes were examined with stereomicroscope. RESULTS: The bond strengths of Tenax post from A1 to F1 were (22.35±3.43) MPa, (22.75±1.92) MPa, (27.21±3.60) MPa, (32.32±2.19) MPa, (36.15±2.32) MPa and (40.51±2.37) MPa, respectively. The bond strengths of Macthpost post from A2 to F2 were (17.29±3.23) MPa, (17.01±3.18) MPa, (20.48±2.11) MPa, (23.60±2.60) MPa, (27.65±3.77) MPa and (30.52±2.99) MPa, respectively. No significantly difference (P>0.05) was found between Group A and Group B, except other groups. CONCLUSIONS: Treatment with H2O2 followed with silane agent can significantly improve the bond strength between Tenax and Macthpost glass fiber posts and resin cement. The group treated with 30% H2O2 has the highest bond strength, and the treatment procedure is more useful to improve the adhesion of the glass fiber post. Supported by Science and Technology Plan Project of Department of Health of Jiangxi Province (20131084).

[In vitro study on shear bond strength of veneering ceramics to zirconia].

OBJECTIVE: To investigate the shear bond strength between veneering ceramic and zirconia core in different all-ceramic systems. METHODS: Twenty disk-shaped specimens with 8 mm in diameter and 3 mm in height for each zirconia system (Lava, Cercon, IPS e.max ZirCAD, Procera) were fabricated respectively and divided into four groups: Lava group, Cercon group, IPS e.max ZirCAD group, Procera group. For each group, 10 specimens were sintered with 1 mm corresponding veneering ceramic, while the other were sintered with 2 mm corresponding veneering ceramic respectively. The shear bond strength and fracture mode of specimens were observed and determined. RESULTS: The values of shear bond strength for Lava, Cercon, IPS e.max ZirCAD and Procera were (13.82 +/- 3.71), (13.24 +/- 2.09), (6.37 +/- 4.15), (5.19 +/- 5.31) MPa in the group of 1 mm thicked veneering ceramics, respectively, while the values in the group of 2mm thicked veneering ceramics were (38.77 +/- 1.69), (21.67 +/- 3.34), (12.70 +/- 4.24), (9.94 +/- 6.67) MPa. The values of Lava and Cercon groups were significantly higher than that of IPS e.max ZirCAD and Procera groups (P < 0.05). And the values of 2 mm thicked veneering ceramic group were significantly higher than that in 1 mm thicked groups (P < 0.05). Adhesive fracture between core and veneering ceramics were observed in the fracture modes of most specimens. CONCLUSION: The shear bond strength of veneering ceramic to the zirconia framework are different from the zirconia system we chose, and the thickness of veneering ceramic has a great impact on its shear bond strength.