Calcium Sulfate Composite Particles for Controlled Bone Augmentation
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Solution Overview
Problem
Conventional calcium sulfate materials used for bone augmentation dissolve too rapidly at the recipient site, outpacing bone growth and requiring improved degradation rates to match bone formation effectively, while existing polymer-based solutions are costly and can have negative effects on bone formation.
Innovation Solution
Calcium sulfate composite particles comprising aggregated nanoparticles of calcium sulfate dihydrate and hemihydrate with a controlled diameter and mean half-life of at least 18 days, produced through an aqueous surface spray wetting and rotational mixing process, which degrade linearly and stimulate bone growth over a prolonged period without the use of synthetic polymers or organic solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional calcium sulfate is used as a cement to fill a bone void, fracture, or other defects in human bone, then it provides immediate structural support, but it dissolves at a rapid rate with complete dissolution in about four weeks, which outpaces the formation of new bone
Solution Approach 1:
The patent segments calcium sulfate into nanoparticle form (50-800 nanometers diameter) rather than using conventional larger particles. This segmentation fundamentally changes the dissolution kinetics, enabling the material to degrade at a controlled rate that matches bone formation speed while maintaining structural support over an extended period (mean half-life of at least 18 days).
Solution Approach 2:
The patent creates a composite material system comprising calcium sulfate nanoparticles combined with bone growth stimulators (such as BMP-2, TGF-beta, or PDGF). This composite approach allows the calcium sulfate to provide structural support while the embedded growth factors stimulate osteogenesis, ensuring the material remains effective throughout the bone formation process without dissolving too rapidly.
2Duration of action of moving object
If polymer-containing calcium sulfate particles are used to slow down dissolution, then the dissolution rate is reduced and retention time is improved, but the cost increases and negative effects on bone formation occur due to acidic degradation products
Solution Approach 1:
The patent extracts and eliminates the polymer component from the calcium sulfate system. Instead of using polymer-coated or polymer-containing calcium sulfate particles, the invention employs pure calcium sulfate nanoparticles combined with bone growth stimulators. This removal of polymers eliminates the source of acidic degradation products (lactic acid from polylactic acid or salicylic acid from polyaspirin) that were causing harmful effects on bone formation, while still achieving the desired controlled dissolution rate through nanoparticle segmentation.
Solution Approach 2:
The patent replaces expensive polymers with a more cost-effective approach using calcium sulfate nanoparticles that naturally provide controlled dissolution. The calcium sulfate itself serves as the temporary scaffold that degrades safely without requiring additional polymer materials, reducing both cost and potential adverse biological effects while maintaining the necessary retention time for bone formation.
3Duration of action of moving object
If calcium sulfate nanoparticles are used to match degradation rate with bone growth, then the degradation rate is controlled, but the material must be retained at the site for a prolonged period without being filled by soft tissue
Solution Approach 1:
The patent incorporates bone growth stimulators (such as BMP-2, TGF-beta, or PDGF) within the calcium sulfate nanoparticle structure. These growth factors provide biological feedback that actively promotes osteogenesis and directs tissue formation toward bone rather than soft tissue. As the calcium sulfate degrades over the extended period (mean half-life of at least 18 days), the embedded growth factors continuously stimulate bone formation, ensuring that the space is filled with bone tissue rather than soft tissue throughout the retention period.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite particles provide a controlled degradation profile that matches bone growth, stimulating bone regeneration effectively and safely, with a prolonged bone growth stimulus, reducing the risk of adverse effects associated with polymer-based solutions and lowering material costs.
Implementation Method 1
calcium sulfate causes precipitation of calcium phosphate deposits as it dissolves at the surgical site
Implementation Method 2
calcium sulfate causes precipitation of calcium phosphate deposits as it dissolves at the surgical site. These precipitates stimulate and direct the formation of new bone
Data Source
AI summary
Calcium sulfate composite particles for bone augmentation are disclosed. The composite particles are composed of aggregated calcium sulfate nanoparticles of a diameter from about 50 to about 800 nm, which include a mixture of calcium sulfate dihydrate and calcium sulfate hemihydrate. The composite particles have a diameter from about 200 to about 1,200 μm, and a mean half-life no less than 18 days. Further disclosed is a bone grafting material for bone augmentation. The bone grafting material includes a mixture of the calcium sulfate composite particles and a second type of calcium sulfate particles having a particle diameter from about 2 to about 60 μm, at a ratio from 1:1 to 4:1. The method of using the composite particles and the bone grafting material for bone augmentation is also disclosed.