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Powder injection molding (PIM) is a hybrid of powder metallurgy and plastic injection molding. It is used to develop metallic molded parts with intricate shapes and with improved properties compared with those offered by their wrought counterparts. PIM dental implants should exhibit biocompatibility, high density, good dimensional control, homogeneous properties and low manufacturing cost. In order to achieve these properties, the effect of boron (additive) addition on sintered density and of process effects on the biocompatibility of sintered implants was studied. In activated sintering, additives are used in small quantities to modify the sintering behavior of stainless steel. A constant amount of nanosize elemental boron (0-1.5 wt%) was admixed with 316L stainless steel and was compounded with complex binder to develop feedstocks using a z-blade mixer. Optimal solvent debinding parameters followed by an optimal sintering cycle played a vital role in the development of biocompatible and densified 316L stainless steel dental implants. Although all boron-containing formulations were injection-molded successfully, only PWA-0.5B-1230 samples were able to retain their shapes after sintering. It was concluded that 0.5 wt% addition of elemental boron favored the formation of 316L stainless steel with a sintered density of up to 98.5 % through the formation of a complex iron boride compound (BFe) on the grain boundaries during the sintering process. The formation of a passive layer on the outer surface of implants was controlled using optimal sintering parameters. In in vitro analysis, the cytotoxicity assessment of sintered dental implants materials was determined using the direct and indirect contact techniques. [ABSTRACT FROM AUTHOR]

Hydroxyapatite bioactive coating was deposited on treated medical grade stainless steel 316L by electrophoretic deposition. Two independent variables including deposition voltage and time span were evaluated in order to investigate their effect on substrates' corrosion potential and coating mass. After deposition, coated substrates were post-treated in a vacuum furnace at 800 $${^{\circ}}$$ C. The experimental plan was based on a central composite design to create a precision of the mathematical models. The precision of mathematical model and relative parameters were evaluated by variance analysis. Optimum parameters value, considered as simultaneous minimum ion release and maximum coating mass, were predicted at the deposition voltage of 25.93 V and deposition time span of 159 s. The validity of the model generated by response surface methodology was evaluated by comparing the predicted and experimental results. In addition, close agreement between experimental and predicted results was observed. [ABSTRACT FROM AUTHOR]