PURPOSE: To measure the surface loss of dental restorative zirconia and the short-term bond strength between an indirect composite resin (ICR) and zirconia ceramic after various sandblasting processes. MATERIALS AND METHODS: Three hundred zirconia bars were randomly divided into 25 groups according to the type of sandblasting performed with pressures of 0.1, 0.2, 0.4 and 0.6 MPa, sandblasting times of 7, 14 and 21 seconds, and alumina powder sizes of 50 and 110 microm. The control group did not receive sandblasting. The volume loss and height loss on zirconia surface after sandblasting and the shear bond strength (SBS) between the sandblasted zirconia and ICR after 24-h immersion were measured for each group using multivariate analysis of variance (ANOVA) and Least Significance Difference (LSD) test (alpha=.05). After sandblasting, the failure modes of the ICR/zirconia surfaces were observed using scanning electron microscopy. RESULTS: The volume loss and height loss were increased with higher sandblasting pressure and longer sandblasting treatment, but they decreased with larger powder size. SBS was significantly increased by increasing the sandblasting time from 7 seconds to 14 seconds and from 14 seconds to 21 seconds, as well as increasing the size of alumina powder from 50 microm to 110 microm. SBS was significantly increased from 0.1 MPa to 0.2 MPa according to the size of alumina powder. However, the SBSs were not significantly different with the sandblasting pressure of 0.2, 0.4 and 0.6 MPa. The possibilities of the combination of both adhesive failure and cohesive failure within the ICR were higher with the increases in bonding strength. CONCLUSION: Based on the findings of this study, sandblasting with alumina particles at 0.2 MPa, 21 seconds and the powder size of 110 microm is recommended for dental applications to improve the bonding between zirconia core and ICR.
Adhesives ; Aluminum Oxide ; Ceramics ; Immersion ; Microscopy, Electron, Scanning ; Multivariate Analysis

On page 219, there was an error in the Fig. 5.

This paper is aimed to investigate the effect of rest-inserted loading on the mechanosensitivity of osteocytes. In the investigation, cultured MLO-Y4 osteocyte-like cells were strained on cyclic compressive force (CCF) by the self-made compressive loading device. Then we observed the effect of different rest periods-inserted loading (5 s, 15 s, 30 s, respectively) on the mechanosensitivity of osteocytes. We then determined the levels of secreted nitric oxide (NO) and prostaglandin E2 (PGE2) by Griess method and enzyme linked immunosorbent assay (ELISA), respectively. We then stained the cytoskeleton F-actin using immunofluorescence. We found that the expressions of NO and PGE2 in rest-inserted strained groups (> 15 s) were significantly increased compared to those in the continuous strained group. And rest-inserted loading promoted the parallel alignment of stress fibers. It indicates that rest-inserted loading could promote the mechanosensitivity of osteocytes, and this might be related to the parallel alignment of stress fibers.
Actins ; metabolism ; Animals ; Cell Culture Techniques ; Cell Line ; Cytoskeleton ; metabolism ; Dinoprostone ; secretion ; Mice ; Nitric Oxide ; secretion ; Osteocytes ; secretion ; Stress, Mechanical

The objective of this research is to evaluate the effects of different silane coupling agents on the bond strength between Ceramco3 opaque porcelain and indirect composite resin. Five groups of Co-Cr metal alloy substrates were fabricated according to manufacturer's instruction. The surface of metal alloy with a layer of dental opaque porcelain was heated by fire. After the surface of opaque porcelain was etched, five different surface treatments, i.e. RelyX Ceramic Primer (RCP), Porcelain Bond Activator and SE Bond Primer (mixed with a proportion of 1:1) (PBA), Shofu Porcelain Primer (SPP), SE bond primer (SEP), and no primer treatment (as a control group), were used to combine P60 and opaque porcelain along with resin cement. Shear bond strength of specimens was tested in a universal testing machine. The failure modes of specimens in all groups were observed and classified into four types. Selected specimens were subjected to scanning electron microscope and energy disperse spectroscopy to reveal the relief of the fracture surface and to confirm the failure mode of different types. The experimental results showed that the values of the tested items in all the tested groups were higher than that in the control group. Group PBA exhibited the highest value [(37.52 +/- 2.14) MPa] and this suggested a fact that all of the specimens in group PBA revealed combined failures (failure occurred in metal-porcelain combined surface and within opaque porcelain). Group SPP and RCP showed higher values than SEP (P < 0.05) and most specimens of SPP and RCP performed combined failures (failure occurred in bond surface and within opaque porcelain or composite resin) while all the specimens in group SEP and control group revealed adhesive failures. Conclusions could be drawn that silane coupling agents could reinforce the bond strength of dental composite resin to metal-opaque porcelain substrate. The bond strength between dental composite resin and dental opaque porcelain could meet the clinical requirements.
Acrylic Resins ; chemistry ; Ceramics ; chemistry ; Composite Resins ; chemistry ; Dental Bonding ; Dental Porcelain ; chemistry ; Humans ; Polyurethanes ; chemistry ; Resin Cements ; chemistry ; Silanes ; chemistry

BACKGROUND:With the development of tissue engineering, porous bioceramics are more and more used to repair bone defects. Current research focuses on the biological synthesis of this bioceramics and its performance evaluation.
OBJECTIVE:To discuss the preparation of a new kind of bone cement and to determine its physicochemical properties and biocompatibility with osteoblasts.
METHODS:Biphasic tricalcium phosphate powders were prepared using co-precipitation method. The powder was turned into granular stuff by arabic gum. After sintering, porous hydroxyapatite/tricalcium phosphate bioceramics were harvested, and then mixed with alpha-hemihydrate to prepare the bone cement.
RESULTS AND CONCLUSION:X-ray diffraction confirmed that the synthetic substance was a kind of biphasic calcium phosphate ceramic having a porous structure. The bone cement could be in the plastic state within 3 minutes. The curing time was 15 minutes, and the curing temperature was 36.5℃. The maximum compression strength was 5.82 MPa, and the MTT toxicity was level 0. Osteoblasts could grew wel on the material surface.

We tried to find the effects of the application of the antibacterial solution containing silver ions on the surface of the denture soft lining material. We selected the right concentration of the silver-containing solution and coated a soft lining material with the solution so that the soft lining material could be antibacterial. The antibacterial solution containing silver ions was prepared by sol-gel method. MIC of C. a and S. a were tested by broth dilution test. The surface property and thickness were tested after coated. The in vitro antibacterial ratio against C. a and S. a were demonstrated by the method of plate-counting. A film was formed after coating, while the adequacy was not changed. Antibacterial ratio of 0.64 mg/ml group against C. a was 90.82%, and that against S. a was 94.96% in 24 hours, respectively. It was found that the antibacterial property of the soft lining material can be acquired by coating this antibacterial solution with silver ion, without changing the adequacy.
Anti-Bacterial Agents ; chemistry ; pharmacology ; Candida albicans ; drug effects ; Denture Cleansers ; pharmacology ; Denture Liners ; microbiology ; Membranes, Artificial ; Microbial Sensitivity Tests ; Silver ; pharmacology ; Staphylococcus aureus ; drug effects

OBJECTIVETo compare the fracture surface of the machinable infiltrated ceramic (MIC) prepared in different conditions, and to relate its strength and toughness to the differences in their microstructures.

METHODSThe Al2O3 matrix were prepared, infiltrated by the machinable glass and crystallized. Based on sintering and infiltrating time and conditions, the specimens were divided into three groups: Perfect group, insufficiently infiltrated group, mal-sintered substrate group. Specimens were fabricated, three point flexural strength and elastic modulus were tested, and the microstructure of the MIC fracture surfaces was analyzed by means of scanning electron micrograph (SEM) observation.

RESULTSThe strength of the insufficiently infiltrated group and mal-sintered substrate group were lower than that of the perfect group, and faults in the microstructure of these two groups also proved this. The foreland of glass infiltrating in the Al2O3 and the interface of glass and complex demonstrated that the Al2O3 surface was smoother than the complex and there was a big crack in the glass but not in the complex which proved the crack resistibility of glass and Al2O3 were smaller than that of the complex (MIC).

CONCLUSIONCorrect preparing process could make the glass infiltrate into properly sintered Al2O3 sufficiently which ensured best mechanical properties of the complex.

The main mineral component of natural tooth was determined as calcium apatite many years ago; most of them exist in the form of hydroxyapatite with different crystallites. If a tooth decayed, the crystalline of hydroxyapatite would be changed and decomposed. In our experiment, a natural tooth with caries was measured by high resolution XRD equipment: X'pert Pro. Three spots which included normal enamel, normal dentin and caries tissue were analyzed. The results showed that tooth was a kind of biological mixed crystal composed of many crystal phases, the main crystal phase was hydroxyapatite. From normal enamel to normal dentin and to caries tissue, the length of the a-axis of hydroxyapatite crystallite increased, the length of the c-axis of hydroxyapatite crystallite remained unchanged. The crystal sizes were: normal enamel D002 = 27.600 nm; normal dentin D002 = 16.561 nm; caries tissue D002 = 13.163 nm. Crystallinity: normal enamel>normal dentin>caries tissue. According to our experiment, tooth could be conveniently studied by high resolution microdiffracion XRD equipment.
Dental Caries ; metabolism ; Dental Enamel ; chemistry ; Dentin ; chemistry ; Humans ; Tooth ; chemistry ; X-Ray Diffraction ; methods

This study was aimed to assess the effects of fluid shear stress on the bone resorption in rat osteoclasts. The osteoclasts were derived from the lumbar vertebrae marrow cells which were isolated from the 6-month-old female Sprague Dawley rats, cultured on the slide at 1 x 10(6) cell/ml, and induced with 1, 25 (OH)2 Dihydroxyvitamin D3. The slide containing osteoclasts was taken out on day 7 after culture and then put into the flow chamber. The loads of fluid shear stress applied to the osteoclasts were 5.97, 11.36, 16.08 and 20.54 dyne/cm2, respectively, for 30 minutes. The osteoclasts unloading fluid shear stress were used as control. The bone resorptive pits were studied by light microscopy and scanning electron microscopy. The tartrate-resistant acid phosphatase (TRAP) secreted by osteoclasts was detected with ultraviolet spectrophotometry. The results showed that fluid shear stress can increase the activity of TRAP and significantly increase the number and area of bone resorptive pits made by osteoclasts,and the effect of fluid shear stress on the bone resorption of osteoclasts is the same as that on the activity of TRAP. The reaction of the osteoclasts to the fluid shear stress in this study also suggested that the bone resorption of osteoclasts be increased in a magnitude of fluid shear stress-dependent manner, and that the changes of TRAP activity be closely related to the changes of the number and area of resorptive pits of the osteoclasts.
Acid Phosphatase ; metabolism ; Animals ; Bone Resorption ; physiopathology ; Calcitriol ; pharmacology ; Cells, Cultured ; Female ; Isoenzymes ; metabolism ; Lumbar Vertebrae ; cytology ; Osteoclasts ; cytology ; enzymology ; physiology ; Rats ; Rats, Sprague-Dawley ; Shear Strength ; Tartrate-Resistant Acid Phosphatase

IPS-Empress2 is a successful all-ceramic restoration system. To lower its cost, and promote its application, a kind of homemade fast investment material has been developed. The aim of this study was to evaluate the expansion properties of this investment material. The setting expansion, thermal expansion and total expansion of the homemade fast investment material were tested. The same properties of the IPS special fast investment material were also tested as control. Then the SPSS statistics software was used to evaluate the differences between the homemade material and the special material. The results show that the setting expansion rate, thermal expansion rate and total expansion rate of the special investment material for IPS-Empress2 are 0.858%, 1.11% and 1.17% respectively, while the same parameters of the homemade investment material are 0.798%, 1.09% and 1.16% respectively. There is no statistically significant difference in these expansion properties between the two investment materials. In conclusion, the expansion properties of homemade fast investment material are comparable to those of the special fast investment material, so it can compensate for the cast contraction of IPS-Empress2 castable ceramic precisely.
Aluminum Silicates ; chemical synthesis ; chemistry ; Crowns ; Dental Materials ; chemical synthesis ; chemistry ; Dental Porcelain ; chemical synthesis ; chemistry ; Lithium Compounds ; chemical synthesis ; chemistry ; Surface Properties ; Tensile Strength