Biodegradable Glass-Ceramics via Mixed Powder Sintering

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Solution Overview

Problem

Conventional bioactive glass-ceramics for artificial bones face issues with either rapid or slow biodegradation, which affects their application and compatibility with the body, as they either lack sufficient mechanical strength or exhibit poor osteo-conductivity.

Innovation Solution

A biodegradable and bioactive glass-ceramic is fabricated by mixing a highly bioactive glass powder with a slowly biodegradable glass powder in specific ratios, controlling the biodegradation rate through the composition and sintering process, comprising calcium oxide, silica, boron oxide, magnesium oxide, and calcium fluoride, to achieve optimal bioactivity and mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a slowly biodegradable glass-ceramic (Cerabone-AW®) is used to maintain high mechanical strength and osteo-conductivity, then mechanical strength is improved, but biodegradation rate deteriorates (too slow)

Engineering Contradiction:

Improvemechanical strengthVSAvoidbiodegradation rate

Core Design Contradiction:

StrengthVSDuration of action of moving object

Solution Approach 1:

The patent creates a composite glass-ceramic material by combining two different glass-ceramic compositions with distinct biodegradation rates. The first glass-ceramic (40-50 wt% SiO2, 30-40 wt% CaO, 10-20 wt% B2O3) provides controlled biodegradation, while the second glass-ceramic (44.7 wt% SiO2, 44.7 wt% CaO, 44.7 wt% MgO, 16.2 wt% P2O5, 0.5 wt% CaF2) provides mechanical strength and osteo-conductivity. By mixing these components in specific ratios, the composite achieves both adequate biodegradation rate and high mechanical strength, resolving the contradiction between slow biodegradation and mechanical strength requirements.

Inventive Principle:

Principle #40Composite materials

2Duration of action of moving object

If a highly bioactive glass is used to achieve rapid biodegradation, then biodegradation rate is improved, but mechanical strength deteriorates (very low)

Engineering Contradiction:

Improvebiodegradation rateVSAvoidmechanical strength

Core Design Contradiction:

Duration of action of moving objectVSStrength

Solution Approach 1:

The patent combines a highly bioactive glass-ceramic composition (first glass-ceramic with specific SiO2, CaO, and B2O3 ratios) that provides rapid biodegradation capabilities with a conventional bioactive glass-ceramic composition (second glass-ceramic similar to Cerabone-AW®) that provides mechanical strength. The composite structure allows the highly bioactive component to control biodegradation rate while the conventional component maintains mechanical integrity, thus resolving the contradiction between rapid biodegradation and mechanical strength.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent systematically varies the mixing ratio of the two glass-ceramic components to optimize the balance between biodegradation rate and mechanical strength. By adjusting the proportion of highly bioactive glass-ceramic (first component) versus conventional glass-ceramic (second component), the patent fine-tunes the biodegradation rate parameter while maintaining adequate mechanical strength, demonstrating parameter change as a method to resolve the contradiction.

Inventive Principle:

Principle #35Parameter changes

3Strength

If conventional bioactive glass-ceramics are used, then mechanical strength is satisfactory, but biodegradation control deteriorates (too fast or too slow)

Engineering Contradiction:

Improvemechanical strengthVSAvoidbiodegradation control

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic control of biodegradation by using a mixed composition of two glass-ceramics where the biodegradation rate can be adjusted based on the mixing ratio. This dynamic approach allows the material to adapt its biodegradation behavior to different application requirements while maintaining satisfactory mechanical strength, resolving the lack of biodegradation control versatility in conventional single-composition glass-ceramics.

Inventive Principle:

Principle #15Dynamics

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 resulting glass-ceramic exhibits controlled biodegradation rates, maintaining bioactivity and mechanical strength, allowing for effective bone integration and growth, while reducing the risk of inflammation and pore structure collapse.

Implementation Method 1

The glass-ceramic composition is compacted at near 830° C., and oxyfluoroapatite (Ca10(PO4)6(O,F)2) and β-wollastonite (CaSiO3) are consecutively crystallized at near 870° C.

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 2

oxyfluoroapatite (Ca10(PO4)6(O,F)2) and β-wollastonite (CaSiO3) are consecutively crystallized at near 870° C.

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS7582310B2Biodegradable and bioactive glass-ceramics, and method for fabricating the same

Publication Date: 2009.09.01 SEOUL NATIONAL UNIVERSITY R&DB FOUNDATION

AI summary

Disclosed herein is a biodegradable and bioactive glass-ceramic fabricated by mixing a slowly biodegradable glass-ceramic and a highly biodegradable glass-ceramic in a predetermined mixing ratio wherein the bioactivity is maintained to be constant, and the biodegradation rate is controlled by the mixing ratio. The biodegradable and bioactive glass-ceramic is fabricated from a composition consisting of calcium oxide (CaO), silica (SiO2), boron oxide (B2O3), magnesium oxide (MgO), calcium fluoride (CaF2) and phosphorus pentoxide (P2O5).