Dental Composite Bulk Fill with Core-Shell Particles
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Solution Overview
Problem
Dental composite materials with high modulus of elasticity are not ideally suited for molar and premolar teeth restorations due to excessive shrinkage and stress on the marginal seal during chewing, and existing solutions like incremental filling techniques are time-consuming and uncomfortable.
Innovation Solution
A dental composite material incorporating non-agglomerated nanofillers and core-shell polymer particles with an elastic core and non-elastic shell, which reduces shrinkage and modulus of elasticity to improve performance in bulk fillings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If highly filled dental composite materials are used to reduce polymerization shrinkage, then volume shrinkage is reduced, but the modulus of elasticity becomes too high causing excessive stress on the marginal seal during chewing
Solution Approach 1:
The patent uses a composite filler system combining nanofillers (1-50 nm) with conventional fillers (glass spheres, pyrogenic silicic acid) to achieve both low shrinkage and appropriate elasticity. The nanofillers provide surface area for bonding while the core-shell particles with soft cores (modulus <18 MPa) and hard shells maintain structural integrity, creating a multi-scale composite that balances shrinkage resistance with chewing stress absorption
Solution Approach 2:
The patent applies local quality through core-shell particles where the core has low modulus (<18 MPa, preferably <10 MPa) to absorb stress locally, while the shell has high modulus to maintain overall structure. This spatial differentiation of mechanical properties allows the material to simultaneously reduce shrinkage and protect the marginal seal from excessive stress concentration
2Manufacturing precision
If conventional filled composite materials are used to achieve low shrinkage, then polymerization shrinkage is reduced, but the material is not ideally suitable for molar and premolar teeth restorations due to high stress exposure
Solution Approach 1:
The patent incorporates core-shell particles with soft cores beforehand to cushion against chewing stresses before they reach the adhesive layer and marginal seal. The soft core material (modulus <18 MPa) acts as a pre-positioned stress absorber that deforms under load, protecting the brittle adhesive interface from sudden stress peaks during molar and premolar chewing cycles
3Strength
If the modulus of elasticity is reduced to decrease stress on the marginal seal, then chewing stress impact is reduced, but the volume shrinkage increases
Solution Approach 1:
The patent employs a composite filler system where nanofillers (1-50 nm) provide high surface area for polymerization shrinkage compensation through their large interfacial area, while core-shell particles with appropriate modulus (<12 GPa preferably) maintain the overall mechanical properties. The combination allows the material to reduce stress on the marginal seal while keeping volume shrinkage within acceptable limits (≤3.0%)
Solution Approach 2:
The patent changes the modulus of elasticity parameter to a specific range (6-12 GPa, preferably 7.0-9.5 GPa) that optimizes the balance between stress absorption and shrinkage control. This parameter optimization, combined with nanofiller incorporation, allows the material to simultaneously achieve low stress exposure and acceptable polymerization shrinkage for bulk filling restorations
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 material achieves a suitable modulus of elasticity and low volume shrinkage, enhancing the marginal seal and comfort during chewing, making it suitable for molar and premolar teeth restorations.
Implementation Method 1
core-shell polymer particles with an elastic core compound, preferably having a modulus of elasticity of less than about 18 MPa
Implementation Method 2
hardening of a dental composite material by polymerization necessarily results in a volume shrinkage
Data Source
AI summary
The invention concerns hardenable dental composite materials, comprising i) non-agglomerated nanofillers having particle sizes of about 1 to about 50 nm; and ii) core-shell polymer particles with an elastic core compound, preferably having a modulus of elasticity of less than about 18 MPa, more preferably of less than 14 MPa, most preferably of less than about 10 MPa; and a substantially non-elastic shell compound. The materials have improved properties that allow for advantageous restoration of molar and premolar teeth with the bulk filling technique.