Enhancement of bone formation on LBL-coated Mg alloy depending on the different concentration of BMP-2.

To control the bio-absorption rate of Mg alloy and improve its biocompatibility, a BMP-2 of various concentrations (20, 50, and 100 ng/mL) was immobilized in the carrier layer formed by micro-arc oxidation + hydrothermal treatment on the surface of Mg alloy. Their morphological and chemical properties were evaluated by FE-SEM with EDS and XRD. The electrochemical corrosion behavior was examined, and the cytotoxicity was assessed by WST and ALP assay. After in vivo test during 2 and 4 weeks in the rat tibia, histological observation was performed. In the carrier layer, calcium phosphate ceramic and oxide layers (MgO and Mg(OH)2) were formed. The layers enhanced the corrosion resistance. It was maintained even after loading the BMP-2. In the BMP-2-loaded group, the proliferation and differentiation of the osteoblast cells were promoted by the continuous release of the BMP-2. After implantation for 2 weeks, all BMP-2-loaded groups showed better biodegradation rate and osseointegration than the control group. After 4 weeks, the group with 50 ng/mL of BMP-2 exhibited the slowest biodegradation rate of all the BMP-2-loaded groups. This effected on the enhancement of new bone formation and the stable bone growth. Therefore, for the short term of implantation, this double coating method could be applied onto biodegradable Mg metal as an orthopedics and dental implant. For the long term of implantation over 4 weeks, to treat Mg implant with 50 ng/mL of BMP-2 was determined to be optimal.

The concentrations of IL-8 and IL-6 in gingival crevicular fluid during nickel-chromium alloy porcelain crown restoration.

We explored gum irritation and cytotoxicity caused by nickel-chromium (Ni-Cr) alloy porcelain by interleukin-8 (IL-8), interleukin-6 (IL-6) and gingival crevicular fluid (GCF) volumes at different time points peri-crown restoration. This prospective study was conducted in 60 young adults. The total amount and concentrations of IL-8 and IL-6 per site, GCF volumes, and blood neutrophil counts were performed prior to and at 1 week, 3 months, and 6 months after Ni-Cr alloy-porcelain crown restoration. Thirty male and 30 female subjects, aged 20-35 years old were enrolled. The total amount and concentrations of IL-8 and IL-6 per site, GCF volumes increased after nickel-chromium (Ni-Cr) alloy-porcelain crown restoration, and reached its peak at the third month as the GCF volume increased by 52.20 %, the total amount and concentrations of IL-8 increased by 112.11 and 22.75 %; the total amount and concentrations of IL-6 increased by 77.66 and 17.17 % when compared to baseline. In particular, the increase of IL-8 concentration was found in female patients at 3 months after restoration; while the neutrophil count of the peripheral blood did not change significantly. The increase in the total amount and the concentrations of IL-8 and IL-6 and GCF volume may be related to the cytotoxicity induced by Ni-Cr alloy. The significant increase of IL-8 concentration in females indicates that more attention should be given to women during Ni-Cr alloy porcelain crown restoration.

Matrix metalloproteinases and inflammatory cytokines in the oral fluid of patients with chronic generalized periodontitis various structural materials restoration of teeth and dentition.

Results of comparative immunoenzymatic study of matrix metalloproteinase (MMP) 2, 8 and 9, interleukins (IL) If and 6, tissue MMP inhibitors (TIMP-1and TIMP-2) and TNF-a in oral fluid of patients with different teeth and denture constructive materials show that MMP-9 content in oral fluid can serve as a marker of chronic generalized periodontitis because it is elevated in all patients irrespective of presence or absence of metallic tooth restorations. MMP-8 level is elevated as compared to control only in periodontitis patients with metallic restorations. The character of correlative relationships between the parameters studied in various patients'groups demonstrate relative similarity of MMP, IL and TIMP secretion regulation in patients with intact periodontal. In patients with inflammatory destructive periodontal lesions both with and without metallic restorations the correlation data reveal a cascade of biochemical reactions in response to etiologic factors. More pronounced response is observed in periodontitis patients with metallic orthopedic constructions. The presence of chromium-cobalt or chromium-nickel constructions leads to an increase of MMP-2, IL-lf and IL-6 content in oral fluid.

[Histamine releasing and immunomodulating activity of dental restorative materials].

Histamine releasing and immunomodulating activity of the following dental restorative materials (DRM) - Prizmafil, Filtek Z250, XRV Herculite Prodigy, Glasiosite, Te-Econol, Valux Plus, Polofil Supra were studied. It was shown that DRM under study as a rule did not possess the ability to release histamine (H) from human blood basophile (BB) excluding Filtek Z250 which release H from BB in patients with allergy and sound donors. The studied DRM implanted under mouse skin were able to modulate immune response to the allergen, at that some of them increased antibodies of IgE-class forming and other suppressed immune response caused by IgG-antibody forming. Received data have certain significance in the scheme of safety evaluation and individual assessment of DRM having acceptable biocompatibility for specific patient.

Initial osteoblast-like cell response to pure titanium and zirconia/alumina ceramics.

OBJECTIVES: Outstanding mechanical properties, resistance to scratching and high biocompatibility make zirconia/alumina ceramics interesting for dental applications. To solve the problem of the well-known low temperature degradation and to provide stable mechanical properties a novel zirconia alloy ((Y,Nb)-TZP/alumina) was developed. The aim of this study was to investigate the initial bone cell response to this new zirconia/alumina composite ceramic. METHODS: HOS cells were cultured on zirconia/alumina composite (Zc) and pure titanium (Ti) discs. Surface topography was examined by atomic force microscopy (AFM), cell morphology by scanning electron microscopy (SEM). Cell proliferation (MTS) and alkaline phosphatase activity was measured at 1, 4 and 8 days. The mRNA expression of Cycline D1, the cell cycle regulating gene, integrin beta 1, osteonectin (ON) and beta-actin were evaluated by RT-PCR analysis after 12, 24 and 48 h. RESULTS: Both substrates showed a very smooth character with R(a)-values in the range of 0.002-0.113 microm supporting a continuous cellular growth. After 8 days, cell proliferation on Zc was higher than on Ti. The mRNA expression of cyclin D1 showed similar activity after 48 h on both surfaces, ALP activity was higher on Zc after 8 days. ON expression however showed no difference between the two groups. SIGNIFICANCE: Our data demonstrate that this new zirconia composite ceramic showed at least equivalent or slightly better biological response of osteoblast-like HOS cells than pure titanium during a short-time cell culture period.

The influence of a chemo-mechanical caries removal solution on the topography of dental ceramic materials.

The purpose of this study was to investigate the chemical influence of chemo-mechanical caries removal (CMCR) on surface topography of dental ceramic materials. Thirty samples of three different types of ceramics (Vita Omega, Vita Alpha, and Procera AllTitan) were manufactured and used. With an optical profilometer, designed with a confocal setting of its optics, (CLSP). and an atomic force microscope (AFM) the surface topography of the specimens was investigated at two different resolutions. The specimens were exposed to a solution (64 mm NaOCl, 27 mM amino acids, pH = 11) supposed to be more aggressive than Carisolv (34 mm NaOCl, 53mM amino acids, pH = 11), a CMCR system commercially available. After exposure for 5, 10, and 20 min, respectively, areas measured were relocated and the surface topography was reinvestigated. Parameters describing the amplitude, spatial, and hybrid topographical variation were calculated. In general, after 20 min CMCR solution exposure, the AFM topographical parameters were reduced for Vita Omega, and increased for Vita Alpha", whereas the CLSP topographical parameters of Procera AllTitan were slightly reduced. Thus, the results of this study showed minor influence on surface topography after exposure to CMCR solution for 20 min on the dental ceramics Vita Omega, Vita Alpha, and Procera AllTitan.

Effects of dental materials on insulin release from isolated islets of Langerhans.

OBJECTIVES: To investigate the possibility of using a whole organ model for evaluating the biological effects of dental restoration materials in vitro. METHODS: The effect on insulin release of isolated Langerhans islets of a series of dental materials was examined. The islets were incubated for 1h with extracts obtained from various dental materials and insulin was assayed radioimmunologically with crystalline mouse insulin. The results were analysed statistically using analysis of variance (ANOVA) and Scheffe's test at a significance level of p < 0.05. RESULTS: One dental ceramic, Vita VMK 95, significantly (p < 0.01) decreased the insulin release, whereas another dental ceramic, Empress (p < 0.01), a partly re-cast high-noble gold alloy (p < 0.001), a modified high-noble gold alloy (p < 0,05), and unalloyed copper (p < 0.001) significantly increased the release of insulin. SIGNIFICANCE: The results demonstrate a new instance of examining the biological effects of dental restoration materials. The method provides information about the effect of different materials on organ level in vitro that can complement other in vitro tests.

Effects of calcium phosphate bioceramics on skeletal muscle cells.

With advances in ceramics technology, calcium phosphate bioceramics have been applied as bone substitutes. The effects of implants on bony tissue have been investigated. The effects upon adjacent skeletal muscles have not been determined. The focus of this work is to elucidate the biological effects of various calcium phosphate bioceramics on skeletal muscles. Four different kinds of powder of calcium phosphate biomaterials including beta-tricalcium phosphate (beta-TCP), hydroxyapatite (HA), beta-dicalcium pyrophosphate (beta-DCP) and sintered beta-dicalcium pyrophosphate (SDCP), were tested by myoblast cell cultures. The results were analyzed by cell count, cell morphology and concentration of transforming growth factor beta 1 (TGF-beta 1) in culture medium. The cell population and TGF-beta 1 concentration of the control sample increased persistently as the time of culture increased. The changes in cell population and TGF-beta 1 concentration in culture medium of the beta-TCP and HA were quite low in the first 3 days of culture, then increased gradually toward the seventh day. The changes in cell population and TGF-beta 1 concentration in culture medium of the silica, beta-DCP, and SDCP were quite similar. They were lower during the first day of culture but increased and reached that of the control medium after 7 days' culture. Most cells on B-TCP and HA diminished in size with radially spread, long pseudopods. We conclude that HA and beta-TCP are thought to have an inhibitory effect on growth of the myoblasts. The HA and beta-TCP may interfere with the repair and regeneration of injured skeletal muscle after orthopedic surgery.

RESTAURACIONES PROVICIONALES

Introducción, Generalidades, Restauraciones provicionales, Técnica Indirecta: instrumental, Técnica indirecta empleada, Caso clínicos, Conclusiones, Bibliógrafia