Method for controlling work time for forming shape of biphasic self-setting calcium phosphate
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Publication Number
US-10322211-B2
Publication Date
2019-06-18
Expiration Date
Abstract
Biphasic self-setting calcium phosphate (SSCP) used for bone graft material and dental material applications having shape formability, shape retentivity, and bone replacement properties in addition to biocompatibility, safety, non-infectiousness, and absence of outflow, wherein the work time for forming the shape of a kneaded material obtained by kneading biphasic SSCP powder and biphasic SSCP liquid is controlled. A method for controlling the work time for forming the shape of biphasic SSCP in which the moldable work time from the start of kneading to the setting of the kneaded material is adjusted to within a range of from 10 seconds to 600 seconds by kneading a biphasic SSCP powder and biphasic SSCP liquid, the biphasic SSCP powder comprising tetracalcium phosphate and α-tricalcium phosphate and the biphasic SSCP liquid comprising a phosphoric acid aqueous solution containing a calcium component.
Core Innovation
The invention describes a method for controlling work time for shape-forming a biphasic self-setting calcium phosphate. The method adjusts the work time to be in a range of 10 seconds to 600 seconds by kneading a biphasic self-setting calcium phosphate powder portion and a biphasic self-setting calcium phosphate liquid portion at a temperature in a range of 10 to 40°C. The work time is defined from the start of kneading until the setting of the biphasic self-setting calcium phosphate.
The biphasic self-setting calcium phosphate powder portion comprises tetracalcium phosphate and α-tricalcium phosphate, and the biphasic self-setting calcium phosphate liquid portion comprises a phosphoric acid aqueous solution containing a calcium component. The calcium component in the liquid portion comprises at least one selected from calcium hydroxide, calcium oxide, and calcium carbonate. The liquid portion is undersaturated with respect to a calcium phosphate compound prior to kneading with the powder portion.
To further control work time, the invention requires a specific relationship between phosphorus and calcium concentrations in the liquid portion. When the phosphorus concentration (mol/L) is taken along an x-axis and the calcium concentration (mol/L) is taken along a y-axis, the (x, y) values are included in the range of a triangle obtained by connecting three points of (2.96, 1.09), (0.592, 0.218), and (7.38, 0.25) by straight lines.
Claims Coverage
The independent claim is one method claim that controls work time for shape-forming a biphasic self-setting calcium phosphate by kneading specified powder and liquid portions under defined temperature and compositional constraints. The inventive features are further refined by dependent claims by adding optional sodium citrate, and by narrowing powder and liquid compositions and concentration windows, including a calcium–phosphorus triangle constraint in the liquid.
Controlling work time within a specified range by kneading at a defined temperature
Adjusting a work time to be in a range of 10 seconds to 600 seconds by kneading a biphasic self-setting calcium phosphate powder portion and a biphasic self-setting calcium phosphate liquid portion at a temperature in a range of 10 to 40°C.
Using a biphasic powder with tetracalcium phosphate and α-tricalcium phosphate
The biphasic self-setting calcium phosphate powder portion comprises tetracalcium phosphate and α-tricalcium phosphate.
Using a phosphoric-acid aqueous liquid containing a calcium component
The biphasic self-setting calcium phosphate liquid portion comprises a phosphoric acid aqueous solution containing a calcium component, wherein the calcium component comprises at least one selected from calcium hydroxide, calcium oxide, and calcium carbonate.
Employing an undersaturated liquid prior to kneading
The biphasic self-setting calcium phosphate liquid portion is undersaturated with respect to a calcium phosphate compound prior to kneading with the biphasic self-setting calcium phosphate powder portion.
Restricting phosphorus and calcium concentrations to a triangle constraint
When a phosphorus concentration (mol/L) of the biphasic self-setting calcium phosphate liquid portion is taken along the x-axis and a calcium concentration (mol/L) of the biphasic self-setting calcium phosphate liquid portion is taken along the y-axis, the values (x, y) are included in the range of a triangle obtained by connecting the 3 points of (2.96, 1.09), (0.592, 0.218), and (7.38, 0.25) by straight lines, respectively.
The claim set centers on achieving a target work time by kneading a powder containing tetracalcium phosphate and α-tricalcium phosphate with a phosphoric-acid aqueous, calcium-containing liquid that is undersaturated prior to kneading, while enforcing concentration constraints in the liquid via a specified phosphorus–calcium triangle.
Stated Advantages
Controlled work time for shape-forming of a biphasic self-setting calcium phosphate.
Rapid room-temperature setting is stated for the resulting composition and process.
Formation of low-crystallinity HA and dense short-fiber-like HA crystals is reported.
Mechanical strength is evaluated using diametral tensile strength.
Improved osteoconductive bone formation is reported in a mouse skull defect model versus commercial comparators.
Documented Applications
Hard tissue regeneration material kit and dental applications are described.
Dental use cases include dentin hypersensitivity relief, caries filling, remineralization, pulp capping, perforation covering, and root canal filling.
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