Porous-Mould Zirconia Blanks for Fast Dental Sintering
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Solution Overview
Problem
Conventional processes for producing zirconia blanks are laborious and require long processing times, especially for achieving desired optical properties like high translucence, with the entire dense-sintering process typically taking over 4 hours.
Innovation Solution
A process involving a suspension of zirconia in a liquid medium introduced into a mould with pores, followed by partial removal of the liquid medium, resulting in a blank that can be densely sintered in a very short time to produce dental restorations with excellent optical and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional slip casting processes are used with nanoscale zirconia particles, then translucent dental restorations can be produced, but the processing time exceeds 4 hours due to lengthy concentration steps, slow drying, and time-consuming dense sintering
Solution Approach 1:
The patent changes the particle size parameter from nanoscale (20 nm) to microscale (0.5-5 μm), which fundamentally alters the drying and sintering characteristics. Larger particles enable faster liquid removal and shorter sintering times while still achieving the required translucence through optimized suspension composition and processing parameters
Solution Approach 2:
The patent performs preliminary concentration of the suspension to achieve optimal solids content (50-80 wt%) before casting. This preliminary action eliminates the need for lengthy post-casting concentration steps and enables rapid drying and sintering, reducing total processing time to under 4 hours while maintaining translucence
2Strength
If conventional slip casting with high zirconia content suspension is used, then mechanical strength is improved, but the suspension requires very slow drying over several days to avoid crack formation
Solution Approach 1:
The patent uses larger particle sizes (0.5-5 μm) which reduce capillary forces during drying, allowing rapid water removal without inducing cracks. The optimized particle size distribution and suspension composition enable fast drying (hours instead of days) while maintaining high mechanical strength through proper particle packing and green compact density
Solution Approach 2:
The patent creates a composite suspension system combining zirconia particles of specific size ranges with optimized binder and dispersant compositions. This composite approach enables both high mechanical strength (through proper particle packing and green strength) and rapid crack-free drying (through reduced capillary stresses from larger particles)
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 process allows for the rapid production of zirconia blanks that can be shaped and densely sintered within one dental session, achieving high translucence and mechanical strength, thus overcoming the limitations of conventional methods.
Implementation Method 1
a mould having pores is used, into which a suspension of zirconia in a liquid medium is introduced, the liquid medium is at least partially removed via the pores
Implementation Method 2
the blank is given the shape of the dental restoration and is densely sintered
Data Source
AI summary
A zirconia blank produced by introducing a zirconia suspension into a porous mould and demoulding the blank formed as well as the use of the optionally presintered blank formed for the preparation of a dental restoration using a very short dense-sintering process.