Dental Mill Blank Curable Composition Crack Resistance
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Solution Overview
Problem
Conventional mill blanks for dental cutting and machining face challenges in achieving high mechanical strength without cracking or breakage, particularly in the context of dental CAD/CAM techniques where materials need to be durable and compatible with natural tooth color and transparency.
Innovation Solution
A curable composition comprising 14 to 36% bifunctional urethane methacrylate monomer, 2 to 12% bifunctional methacrylate monomer without a urethane group, 60 to 80% inorganic filler, and 0.1 to 0.5% thermal polymerization initiator, along with a chain transfer agent, is used to create a mill blank that is molded and cured, optimizing mechanical properties and preventing cracks and breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional curable compositions are used for molding mill blanks, then the material can be processed and cured, but the mill blanks exhibit cracks and breakage with insufficient mechanical strength
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of multiple monomer components. Specifically, it uses a bifunctional urethane methacrylate monomer (14-36 mass%), a bifunctional methacrylate monomer without urethane group (2-12 mass%), and a multifunctional methacrylate monomer (1-10 mass%), along with specific inorganic fillers (60-80 mass%). This optimized compositional parameter range ensures complete polymerization without residual monomers that cause strain, achieving both high mechanical strength and crack resistance.
Solution Approach 2:
The patent employs composite materials by combining multiple monomer types with different functional groups (urethane methacrylate, methacrylate without urethane, multifunctional methacrylate) and inorganic fillers. This composite approach creates a synergistic effect where each component contributes specific properties: the urethane methacrylate provides flexibility, the methacrylate monomers provide strength, and the inorganic fillers enhance durability, resulting in a mill blank material that achieves both high strength and reliability without cracking.
2Duration of action of stationary object
If the mechanical strength is increased to prevent breakage, then the durability improves, but the material becomes more prone to cracking during molding and curing
Solution Approach 1:
The patent resolves this contradiction through parameter changes in the monomer composition. By using a specific ratio of flexible urethane methacrylate monomer (14-36 mass%) combined with strengthening methacrylate monomers (2-12 mass%), the material achieves optimal balance: the urethane groups provide chain flexibility that prevents cracking during molding, while the crosslinking methacrylate groups ensure high durability after curing. The multifunctional monomers (1-10 mass%) further enhance crosslinking density for durability without excessive rigidity.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating flexible urethane methacrylate monomer components into the composition before molding. These flexible polymer chains act as cushioning elements that absorb and distribute stress during the molding and curing process, preventing crack initiation. This pre-built flexibility cushioning allows the material to be easily manufactured without cracking while maintaining high durability after curing.
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 proposed composition significantly enhances the mechanical properties and manufacturability of mill blanks, ensuring high bending strength and minimizing cracks and breakage, thereby improving the durability and performance of dental prosthesis devices.
Implementation Method 1
0.1 to 0.5% by mass of (D) thermal polymerization initiator
Data Source
AI summary
[Problem]It has been difficult to prepare a mill blank for dental cutting and machining in a state of no cracks or breaks.[Solution]To provide a curable composition for use in a mill blank for dental cutting and machining, comprising14 to 36% by mass of (A) bifunctional urethane methacrylate monomer represented by Formula 1,2 to 12% by mass of (B) bifunctional methacrylate monomer not containing a urethane group,60 to 80% by mass of (C) inorganic filler,0.1 to 0.5% by mass of (D) thermal polymerization initiator, and0.1 to 0.5% % by mass of (E) chain transfer agent.