Quartz Solid Solution Glass Ceramic Dental Restorations
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Solution Overview
Problem
Existing glass ceramics for dental applications lack a combination of high strength, good translucency, and adjustable thermal expansion, making them unsuitable for effective use as restorative dental materials.
Innovation Solution
A glass ceramic with a quartz solid solution phase, comprising specific components such as SiO2, Li2O, Al2O3, P2O5, and ZrO2, which allows for high strength, easy processing, and adjustable thermal expansion, along with the incorporation of stoichiometric and non-stoichiometric quartz solid solution phases for enhanced optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass ceramics with high Al2O3 content (≥25.9 wt.-%) are used to achieve high strength, then mechanical strength is improved, but translucency deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by limiting Al2O3 to 1.6-4.0 wt.-% (significantly lower than prior art's ≥25.9 wt.-%) while increasing SiO2 to 54.1-67.0 wt.-% and adding specific amounts of ZrO2 (7.0-13.5 wt.-%), P2O5 (4.1-6.5 wt.-%), and Li2O (13.1-18.5 wt.-%). This parameter optimization resolves the contradiction by achieving high strength through a different compositional pathway that preserves translucency.
Solution Approach 2:
The patent creates a composite glass ceramic system combining multiple crystal phases (quartz solid solution, lithium disilicate, lithium metasilicate) within a specific glass matrix composition. This composite approach allows the material to simultaneously achieve high mechanical strength from the crystalline phases and good translucency from the optimized glass matrix, avoiding the need for high Al2O3 content that would compromise optical properties.
2Strength
If glass ceramics are designed for high strength with secondary crystal phases, then mechanical properties are improved, but optical properties (translucency and colorability) deteriorate
Solution Approach 1:
The patent optimizes the composition parameters to contain controlled amounts of specific crystal-forming oxides (ZrO2: 7.0-13.5 wt.-%, P2O5: 4.1-6.5 wt.-%, Al2O3: 1.6-4.0 wt.-%) within a silica-rich matrix. This precise parameter control enables the formation of a specific multi-phase microstructure that provides high mechanical strength while maintaining sufficient translucency and colorability for dental applications.
Solution Approach 2:
The patent creates different phases with different functions: the glass matrix provides translucency and colorability, while the dispersed crystal phases (quartz solid solution, lithium disilicate, lithium metasilicate) provide mechanical strength. This local differentiation of properties within the composite material resolves the contradiction between mechanical and optical requirements.
3Strength
If glass ceramics are processed at high temperatures to achieve dense sintering, then density and strength are improved, but shape stability deteriorates
Solution Approach 1:
The patent modifies the compositional parameters by incorporating specific amounts of ZrO2 (7.0-13.5 wt.-%) and P2O5 (4.1-6.5 wt.-%) along with Li2O (13.1-18.5 wt.-%), which create a glass matrix with optimized viscosity characteristics. This allows the material to be densely sintered at high temperatures while the controlled composition prevents excessive viscous flow that would cause shape distortion, thus maintaining shape stability during high-temperature processing.
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 glass ceramic achieves a balance of mechanical and optical properties, enabling it to be easily shaped and colored to mimic natural tooth material, with adjustable thermal expansion and high biaxial fracture strength, making it suitable for dental restorations.
Implementation Method 1
The term 'quartz solid solution phase' refers to a crystal phase of SiO2 in which foreign atoms are incorporated into the lattice of the SiO2 either in interstitial sites or in lattice sites
Implementation Method 2
The glass ceramic is obtained by heat treatment of a corresponding starting glass or a corresponding starting glass with nuclei
Data Source
AI summary
Quartz solid solution glass ceramics and precursors thereof are described, which are characterized by very good mechanical and optical properties and can be used in particular as restorative materials in dentistry.