Effects of silica sputtering on adhesion between zirconia and composite resin cores.

Radiofrequency magnetron sputtering of silicon was applied onto zirconia surfaces by use of a non-doped Si wafer at 2%, 5%, 8%, and 10% oxygen volumes. Immediately after sputtering, the contact angle was practically 0 for all oxygen volume specimens. In terms of sustainability of the hydrophilicity, however, 5% oxygen volume was found to be optimal. Scanning electron microscopy and energy dispersive X-ray spectroscopy clearly suggested the presence of silica layer on zirconia surfaces. The shear bond strength of the pre-treated zirconia and resin was 35.03±4.97 MPa, which was approximately 3.5 times higher than that of zirconia without any sputtering treatment (9.26±1.21 MPa). The failure mode of the pre-treated zirconia specimen was cohesive failure, whereas that of the control specimen was observed to be interface failure.

Horseradish peroxidase interacts with the cell wall peptidoglycans on oral bacteria.

Salivary peroxidase and myeloperoxidase are known to display antibacterial activity against oral microbes, and previous indications have pointed to the possibility that horseradish peroxidase (HRP) adsorbs onto the membrane of the major oral streptococci, Streptococcus mutans and Streptococcus sanguinis (S. sanguinis). However, the mechanism of interaction between HRP and the bacterial cell wall component is unclear. Dental plaques containing salivary glycoproteins and extracellular microbial products are visualized with 'dental plaque disclosing agent', and are controlled within dental therapy. However, current 'dental plaque disclosing agents' are difficult to evaluate with just dental plaques, since they stain and disclose not only dental plaques but also pellicle formed with salivary glycoproteins on a tooth surface. In this present study, we have demonstrated that HRP interacted with the cell wall component of the major gram-positive bacterial peptidoglycan, but not the major cell wall component of gram-negative bacteria lipopolysaccharide. Furthermore, we observed that the adsorbed HRP labeled with fluorescence was detected on the major oral gram-positive strains S. sanguinis and Streptococcus salivarius (S. salivarius), but not on a gram-negative strain, Escherichia coli (E. coli). Furthermore, we have demonstrated that the combination of HRP and chromogenic substrate clearly disclosed the dental plaques and the biofilm developed by S. sanguinis, S. salivarius and the major gram-postive bacteria Lactobacillus casei on tooth surfaces, and slightly disclosed the biofilm by E. coli. The combination of HRP and chromogenic substrate did not stain either the dental pellicle with the salivary glycoprotein mucin, or naked tooth surfaces. These results have suggested the possibility that the adsorption activity of HRP not only contributes to the evaluation of dental plaque, but that enzymatic activity of HRP may also contribute to improve dental hygiene.

[Impacted ureteral stents with cystine encrustation in cystinuric patients : report of two cases].

A 23-year-old man and a 62-year-old man suffering from cystinuria underwent extracorporeal shock wave lithotripsy (ESWL) for right renal stone and left ureteral stone, respectively. They had double-J stents placed before ESWL, but since attempts to retrieve the stents were unsuccessful due to encrustation, they were referred to our clinic. Multimodal endourologic and open approaches including ESWL, transurethral ureterolithotripsy, and pyelolithotomy were required to render them stent- and stone-free. The guidelines do not recommend routine stenting before ESWL ; therefore, the indication and duration of indwelling stents should be minimized. Multimodal options including not only ESWL and endoscopic surgery but also open surgery, should be attempted for the management of encrusted stents. Close monitoring and follow up are important to the prevent complications of ureteral stents.

Effects of dental porcelain containing silver nanoparticles on static fatigue.

The purpose of this study was to clarify the effect of silver nanoparticles on the behavior of subcritical crack growth (SCG) in dental porcelains. Prior to occurrence of fast fracture in dental porcelains, SCG occurs and leads to strength degradation over time. SCG in dental porcelains can be characterized by the stress corrosion susceptibility coefficient, n. A higher n value means a higher resistance to SCG. In this study, porcelain disks were prepared by mixing a commercial dental porcelain powder with different concentrations of silver nanoparticles, and then air-dried and fired according to manufacturer's instructions. Stress corrosion susceptibility coefficients of powder compacts were determined using a post-indentation method. A Vickers indenter was applied to the porcelain surface, and lengths of median cracks were measured at fixed time intervals over a 24-h period to calculate n. Addition of silver nanoparticles significantly increased the stress corrosion susceptibility coefficient of dental porcelain.

Effects of adding silver nanoparticles on the toughening of dental porcelain.

STATEMENT OF PROBLEM: Dental porcelains currently used for ceramic restorations are brittle, and it is sometimes necessary to replace fractured or chipped restorations. Porcelain is fragile and exhibits elastic deformation rather than plastic deformation, leading to fracture or chipping of restorations. PURPOSE: The purpose of this study was to investigate the toughening of porcelain through the addition of silver nanoparticles. MATERIAL AND METHODS: Noritake Super (NS) Porcelain AAA modified with the addition of silver nanoparticles was used. The concentration of silver in the solution was adjusted to 100, 200, 500, and 1000 ppm (Ag100, Ag200, Ag500, and Ag1000). The Vickers hardness (Hv) and median crack length extending from the corner of each indent were measured. The fracture toughness (KIC) was calculated by the indentation method. Optical reflectance spectra were recorded by using a spectrometer in the wavelength range of 200 to 700 nm. X-ray diffraction spectroscopy, color measurement, Fourier transform infrared spectroscopy, and electron probe microanalysis were also performed. The observed values of Hv, 2a, E, and KIC were compared and evaluated with a 1-way ANOVA, followed by the Bonferroni method (α=.05). RESULTS: The addition of silver nanoparticles significantly increased the Hv of all specimens with the exception of Ag100. The median crack length was significantly smaller in Ag500 (104.5 µm, SD: 11.9) and Ag1000 (100.0 µm, SD: 5.5). Significantly higher toughness values were observed for Ag500 (1.54 MPa·m(1/2), SD: 0.05) and Ag1000 (1.51 MPa·m(1/2), SD: 0.08) than for the control (1.36 MPa·m(1/2), SD: 0.03). In terms of color difference, Ag500 (5.08, SD:1.32) and Ag1000 (5.47, SD:1.05) had values significantly greater than ΔE*=2.69. CONCLUSIONS: The addition of silver nanoparticles significantly increased the fracture toughness and Vickers hardness of the NS porcelain. A residual compressive stress was generated due to the ion exchange reaction and differential thermal expansion of the silver metal nanoparticles. However, the addition of Ag500 and Ag1000 nanoparticles led to a color change.

Addition of platinum and silver nanoparticles to toughen dental porcelain.

Several studies have investigated toughening porcelain that is layered over a frame or a core. The introduction of residual compressive stress to the surface of porcelain has been shown to be effective to strengthen it. In the present study, nanoparticles of precious metals of silver and platinum (rather than non-precious metals) were used to evaluate if they could increase the fracture resistance of porcelain. The addition of silver and platinum nanoparticles was found to improve the mechanical properties of porcelain since it increased both the Young's modulus and the fracture toughness of commercial porcelain.

Toughening of CAD/CAM all-ceramic crowns by staining slurry.

The ability of staining slurries containing silver and/or potassium compounds to enhance the mechanical properties of a leucite-reinforced glass ceramic (IPS Empress CAD) was investigated by measuring the Vickers hardness, median crack length, toughness, and compressive residual stress of specimens. A staining slurry containing potassium ions was found to increase the toughness of IPS specimens more than a staining slurry containing only silver ions when applied prior to sintering. None of the staining slurries produced any color changes. Thus, the results obtained in this study demonstrate that staining slurries increase the Vickers hardness and the fracture toughness of the surface and subsurface regions of all-ceramic IPS blocks fabricated by a CAD/CAM system without sacrificing their aesthetics.

[A case of primary urothelial carcinoma of the prostate responsive to MVAC intra-arterial chemotherapy: a case report].

A 70-year-old man visited a urological clinic on May 2008 complaining of dysuria and nocturia since 2 years prior. He was diagnosed as having gross benign prostatic hypertrophy, and was referred to a nearby hospital for transurethral resection of prostate (TURP). During TURP, a papillary tumor was found in the prostatic urethra on the left side and a biopsy was performed. A pathological examination revealed urothelial carcinoma G3. Cystoprostatectomy was planned, but the patient refused the procedure. Therefore, he underwent three courses of MVAC intra-arterial chemotherapy (methotrexate, vinblastin, doxorubicin, cisplatinum) at our hospital. After chemotherapy, no tumor was found in the prostatic urethra and a pathological report of repeat TUR showed no tumor. Currently, the patient is alive and there has been no evidence of recurrence for 1 year and 10 month.

A case of amniotic band syndrome with cleft lip and palate.

The patient was a 5-day-old boy born at 37 weeks and 4 days. At birth, an amniotic band encircling and constricting his left middle finger was noted, in addition to multiple anomalies including a right-side cleft lip and palate, a club foot, and syndactyly on the left hand. We performed cheiloplasty at 5 months, and palatoplasty at 18 months.

Osteoclast and osteoblast activities on carbonate apatite plates in cell cultures.

Previous studies have demonstrated that carbonate apatite (CA) is superior to hydroxyapatite (HA) and ß-tricalciumphosphate (ß-TCP) with regard to osteoclastic resorption, but evidence on osteoclast and osteoblast response remains controversial. In the present study, the expression of bone related mRNA is examined on CA, HA, ß-TCP, and titanium plates. ICR mouse osteoblast cells are cocultured with ICR mouse bone marrow cells. Crude osteoclast-like cell-rich suspensions are then seeded onto plates and cultured for 48 h. Total RNA is extracted and mRNA expression is examined by real-time RT-PCR. Amounts of vacuolar-type ATPase, cathepsin K, and TRAP mRNA are significantly greater on CA than on the other plates. The amount of osteoprotegerin mRNA is significantly greater on CA than on the other plates. RANKL mRNA expression, which is generally regarded as an osteoblast maker, varies with material, but shows no significant differences between CA and the other plates. The formation and activity of osteoclasts is greater with CA than with the other plates. Thus, CA is superior to ß-TCP as a bioresorbable bone substitute for tissue engineering.

Polycationic protamine for water-insoluble complex formation with DNA.

The DNA/protamine complex was prepared by a reaction between DNA and protamine sulfate solutions with stirring, and its cell viability, antibacterial effect and histopathological responses were examined. A water-insoluble white powder, DNA/protamine complex, with a porous structure was obtained. The molar binding ratio of the complex prepared from a solution containing equal amounts of DNA and protamine sulfate by weight was 0.038 and the efficiency of complex formation was 61%. In a cell culture test using MC-3T3-E1 mouse osteoblast cells, the complex showed less cytotoxicity than protamine sulfate alone and cell viabilities were more than 98%. A porous disk could be prepared easily and showed an antibacterial effect against Staphyrococcus aureus, Porphyromonas gingivalis and Prevotella intermedia in an antibacterial sensitivity test and a mild tissue response in vivo test. These results suggested that the DNA/protamine complex could be a useful biodegradable biomaterial with antibacterial effects.

Bone tissue engineering using porous carbonate apatite and bone marrow cells.

Porous blocks of carbonate apatite (CA) were prepared by holding together CA particles ranging in size from 300 to 500 microm through sintering at 750 degrees C for 2 hours. Bone marrow cells taken from Fischer rats were seeded onto and inside the CA blocks and cultured for 14 days to allow stem cells to proliferate to osteoblasts capable of inducing bone formation. Hybrids made of CA blocks and cultured bone marrow cells were then implanted into the back of syngeneic rats. Microfocus x-ray computed tomographic images of tissues containing CA blocks before decalcification suggested that new bone was formed in this extraosseous site 4 and 8 weeks after implantation. These data indicate that the hybrid made of CA and bone marrow cells is capable of inducing heterotopic bone formation in vivo.

Does the expression of HPV16/18 E6/E7 in head and neck squamous cell carcinomas relate to their clinicopathological characteristics?

Human papilloma virus (HPV) has been recently proposed to be implicated in the development of head and neck squamous cell carcinoma (HNSCC) in patients without cancer risk. We examined the expression of HPV16/18 E6/E7 in 71 cases of HNSCCs and investigated abnormalities of the p53 gene in 62 of these 71 cases. Expression of HPV16 E6/E7 was observed in 11 of the 71 cases (15.5%), while expression of HPV18 E6/E7 was not observed in any of the cases. Most of the HPV16 E6/E7-positive cases were histopathologically characterized by their verrucous or papillary structure and koilocytosis of the adjacent mucosa. There was no clear relationship between expression of HPV16 E6/E7 and tumor stage, prognosis or the positive rate of p53 abnormality. These results suggest that approximately 15% of HNSCCs are caused by HPV16 infection and the subsequent constitutive expression of E6 and E7, and that some HPV-initiated tumors lose their original characteristics during tumor progression.

The development of carbonate-containing apatite/collagen composite for osteoconductive apical barrier material.

The current report describes the properties of a new apical barrier material formulated from carbonate-containing apatite (CAp) and collagen. CAp particles of around 50 nm were deposited on reconstituted collagen fibers. CAp/col with about 60 wt % CAp (corresponding to apatite content of bone) was obtained after 1 day of calcification. CAp content increased up to about 80 wt % in a 15-day calcification reaction. CAp/col was composed of fine calcified collagen fibers. The crystallinity and Ca/PO(4) ratio of CAp were comparable to those of bone apatite. The mixture of CAp/col and saline reached a pH of about 9. The optimum powder-to-liquid ratio (P/L) to set into a root canal was determined to be 1.2. Furthermore, the mixture (P/L = 1.2) condensed in a root canal was liquid permeable. Thus, the CAp/col was expected as an apical barrier material with osteoconductivity.

Superplastic deformation in carbonate apatite ceramics under constant compressive loading for near-net-shape production of bioresorbable bone substitutes.

To produce carbonate apatite (CAP) ceramics with the desired complex shapes using superplastic deformation, deformation behavior of CAP ceramics under constant loading as well as physical properties after deformation were evaluated. Sintered CAP ceramics were plastically deformed in an electric furnace attached to a universal hydraulic testing machine under a constant load. CAP ceramics subjected to an initial compressive pressure of 10 MPa showed an appreciable amount of plastic deformation at temperatures ranging from 720 to 800 degrees C. Plastic deformation increased with increasing temperature from about 10% to 70% after two hours of loading. X-ray diffraction analysis and SEM observation further revealed that some CAP crystals were elongated and aligned with the c-axis normal to the loading direction during superplastic deformation. It was thus concluded that a marked plastic deformation of about 70% at 800 degrees C would be sufficient for near-net-shape production of bioresorbable CAP bone substitutes with complex shapes.

Expression and cellular localization of TSC-22 in normal salivary glands and salivary gland tumors: implications for tumor cell differentiation.

TGF-beta-stimulated clone-22 (TSC-22) was reported to be a differentiation-inducing factor which negatively regulates the growth of salivary gland cancer cells. In the present study, we examined the expression of TSC-22 in salivary gland tumors by immunohistochemistry. In pleomorphic adenoma (PA), most of the sparse myoepithelial-like tumor cells, which are considered as the differentiated cells because they produce extracellular matrix, expressed TSC-22. However, only a limited number of cases of the solid myoepithelial-like tumor cells in PA, which are considered as the growing cells, expressed TSC-22. In adenoid cystic carcinoma (ACC), inner ductal cells in the tubular structure, strongly expressed TSC-22, though the outer myoepithelial-like tumor cells did not express TSC-22. In the cribriform structure, myoepithelial-like tumor cells did not express TSC-22. However, a small ductal structure in the micro-cyst wall strongly expressed TSC-22. Sparse type myoepithelial-like tumor cells in ACC also expressed TSC-22. In mucoepidermoid carcinoma, epidermoid tumor cells and mucous-producing tumor cells in mucoepidermoid carcinoma frequently expressed TSC-22. Thus, the expression of TSC-22 was frequently observed in the cells with differentiated-phenotypes, although rarely in the cells with growing potentials. These results suggest that TSC-22 may play an important role in maintaining the differentiated phenotype in salivary gland tumors.

Ultrastructural characterization of tissue response to sintered carbonate apatite in rabbit bone.

Our previous in vivo and in vitro studies revealed excellent tissue biocompatibility and osteoconductivity of porous sintered carbonate apatite (CA). The present study focused on the ultrastructural details of cells involved in the degradation of CA and new bone formation. Electron microscopy indicated that multinucleated giant cells (MNGCs) were actively involved in CA resorption. MNGCs extended their irregular cytoplasmic protrusions deeply into the interstitial spaces between CA particles. Endophagosomes were formed by encircling partially dissolved or intact CA crystals via the development of pseudopodia-like cytoplasmic protrusions, the configuration of which was somewhat different from that of the typical ruffled border of bone-resorbing osteoclasts. Subsequently, most CA particles in MNGCs were irregular in shape, suggesting that acidic degradation of CA occurred mainly intracellularly. Mononuclear cells, such as macrophage-like and/or fibroblast-like cells, also took up and degraded some CA. Growth of very thin needle-like crystals was observed in close association with CA. Osteoblasts directly faced the CA and secreted osteoid matrix. At the CA-bone interface, an electron-dense and homogeneous thin layer free of collagen fibers was sometimes observed, suggesting an involvement in CA-bone bonding.

Comparison of carbonate apatite and beta-tricalcium phosphate (resorbable calcium phosphates) implanted subcutaneously into the back of rats.

Bioresorption and biocompatibility of carbonate apatites, both sintered and non-sintered (S-CAP and N-CAP), and of sintered beta-tricalcium phosphate (beta-TCP) were compared by implanting particles of these materials into the back of adult rats. Bioresorption--when evaluated non-destructively with non-decalcified tissues using microfocus X-ray tomography--was essentially the same for N-CAP and beta-TCP, while S-CAP exhibited statistically lower bioresorption at 2, 4, and 12 weeks postoperatively. Biocompatibility--when evaluated by ED1 immunostaining--was in the order of beta-TCP > N-CAP > S-CAP. The intensity of ED1 immunostaining decreased with time, but persisted longer in beta-TCP than in S-CAP and N-CAP, indicating that beta-TCP produced the strongest and most enduring stimulation of macrophages. Although no statistical differences were found in tartrate-resistant acid phosphatase (TRAP) staining among the materials at each implantation period, the degree of TRAP staining for S-CAP was statistically greater at 12 weeks than at 2 and 4 weeks, indicating that osteoclast-like cells were in part responsible for the resorption of the carbonate apatite.

Control of apatite crystal growth by the co-operative effect of a recombinant porcine amelogenin and fluoride.

Recently, we used native amelogenins extracted from developing pig enamel to examine the combined effect of fluoride and amelogenins on the growth of octacalcium phosphate (OCP) and apatite crystals. The purpose of the present study was to investigate this combined effect using a highly purified recombinant amelogenin. We applied porcine amelogenin (rP172) and fluoride in a dual-membrane system as a model for tooth enamel formation. The combination of rP172 and fluoride in this system resulted in the formation of rod-like apatite crystals. On the other hand, without fluoride, rod-like OCP crystals of a comparable size were formed, and rather large hexagonal prisms of mixed crystals of OCP and apatite grew without amelogenins. Thus, highly purified and homogeneous recombinant amelogenin, in co-operation with F, regulated the mineral phase, habit, and size of crystals in the same manner as the extracted heterogeneous porcine amelogenins. We suggest that in both cases the control over the crystal phase and morphology was a direct effect of amelogenin protein serving as a scaffold for apatite mineralization.