CA 242 from Metastatic liver (Immunogen grade)

Objectives: The purpose of the study was to evaluate the effect of two collagen cross-linking agents, glutaraldehyde and grape seed extract (GSE), on the modulus of elasticity of demineralized dentin, when used at different concentrations and exposure times. Type I collagen provides tissues and organs with tensile strength, form, and cohesiveness. It is thought that increasing the strength of the dentin matrix using cross-linking agents might improve both the strength and the durability of resin-dentin bonds. Materials and Methods: Sound extracted molar teeth were ground flat and the teeth were sectioned into 0.5-mm beams and trimmed with a bur to create rectangular blocks of dentin. These were etched with 10% phosphoric acid for 5 hours to cause complete tissue demineralization. They were then treated with 2.5%, 5%, or 25% glutaraldehyde (Fisher Biotech, Fair Lawn, NJ) and 0.65% or 6.5% grape seed extract Mega-Natural (Polyphenolics, Madera, CA). The specimens were immersed in water for baseline measurements and then in their respective solutions for 10 minutes, 30 minutes, 1 hour, 2 hours, and 4 hours of cumulative exposure. Modulus of elasticity was measured using a three-point bend method. A total of 10 to 12 specimens were evaluated per group. Results: The mean baseline modulus of elasticity (E) values varied between 4.8 and 6.2 MPa in water. After 4 hours of treatment, the values increased up to 34.9 and 242.5 MPa, depending on treatment time and cross-linking agent. The 25% glutaraldehyde resulted in a significantly more rapid rise in E after 10 minutes than 2.5% and 5%, and the use of 0.65% and 6.5% GSE resulted in a statistically significant increase in the E of demineralized dentin following each time tested, with 6.5% GSE being the highest. A statistically significant interaction was observed between the factors studied (treatment and time). Conclusions: Demineralized dentin stiffness is affected by the use of glutaraldehyde and grape seed extract collagen cross-linking agents. The changes to the dentin matrix after treatment with the cross-linkers were both concentration and time dependent.

The aim of this work was to evaluate the effects of sintering temperature over the structural, physical and mechanical properties in addition to the in vivo biological performance of nanostructured biocomposites obtained from the mixture between calcined fish bone (hydroxyapatite + beta-tricalcium phosphate) and niobium pentoxide. The sintering temperatures varied from 650 to 1150 degrees C, in steps of approximately 50 degrees C. The results showed the formation of a stable triphasic nanostructured bioceramic with almost constant relative proportions between the CaNb2O6 , PNb9O25 and Ca-3(PO4)(2) phases. Special attention was given to the sintering temperature at 1080 degrees C because there was occurrence of a liquid phase, and the sample showed localised maximisations of linear shrinkage, density and Vickers hardness. This niobium-biphasic calcium phosphate 1080 (Nb-BCP-1080) nanostructured biocomposite presented measured values for compressive strength (242 +/- 29 MPa), Young's modulus (19.63 +/- 3.5 GPa), Poisson's ratio (0.248 +/- 0.016) and flexural strength (24 +/- 5.9 GPa) close to those of some human bones. Then, to further explore these characteristics, in vivo studies were performed by implanting 8.0-mm diameter discs of this material in calvaria of rats. Histological observation showed the occurrence of osseointegration between the neo-formed bone and the triphasic bioceramic just 45 days after implantation. In conclusion, the observations of this work unambiguously show that CaNb2O6-PNb9O25-Ca-3(PO4)(2) triphasic bioceramics are candidates for bone replacements where high and medium loads are demanded.