Self-Adhesive Dental Cement Redox Initiation
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Solution Overview
Problem
Current dental cements face challenges such as moisture susceptibility, solubility, and complexity in application, particularly in achieving self-adhesive and self-etching capabilities without deactivating the polymerization initiating system, and require multiple steps for bonding, which limits their use in indirect restorations.
Innovation Solution
A self-adhesive cement with a dual-curing system using cumene hydroperoxide as a thermally stable oxidizer and benzoyl thiourea as a reducing agent, packaged in a two-part paste/paste system, allowing for self-etching and self-adhesion without the need for additional etching or bonding agents, and maintaining stability and bond strength comparable to existing materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an acidic monomer is included in the formulation to achieve self-etching and self-adhesive capability, then adhesion to tooth structure is improved, but the polymerization initiating system is deactivated due to acid-base reaction converting tertiary amine to protonated form
Solution Approach 1:
The patent changes the chemical parameters of the initiating system by replacing the aromatic tertiary amine with a non-amine reducing agent that does not undergo acid-base reactions with acidic monomers. This allows the system to maintain polymerization capability in acidic environments while achieving self-etching functionality.
Solution Approach 2:
The patent introduces a hydroquinone derivative as an intermediary substance that mediates between the acidic monomer and the oxidizing agent. This intermediary enables electron transfer for polymerization initiation without being deactivated by protons, thus bridging the gap between acidic etching requirements and polymerization needs.
2Power
If benzoyl peroxide is used as the oxidizing agent in the initiating system, then self-curing capability is achieved, but storage instability occurs particularly in the presence of acidic species
Solution Approach 1:
The patent changes the chemical identity of the oxidizing agent from benzoyl peroxide to a hydroquinone derivative, which has fundamentally different stability characteristics. The hydroquinone derivative resists decomposition in acidic environments and maintains storage stability while still providing the necessary oxidizing power for polymerization when activated.
3Strength
If multiple steps including acid application, primer, and bonding agent are used to achieve adhesion to dentin, then bond strength is improved, but device complexity and technique sensitivity increase
Solution Approach 1:
The patent merges multiple separate functions (etching, priming, and bonding) into a single integrated cement formulation. The acidic monomer provides etching capability, the hydrophilic groups provide priming function, and the polymerizable groups provide bonding strength, all in one material that eliminates the need for separate application steps.
Solution Approach 2:
The cement formulation achieves multi-functionality by incorporating acidic monomers that can simultaneously etch tooth structure, prime the surface through hydrophilic interactions, and form strong bonds through polymerization. This universal material replaces multiple specialized products with a single versatile solution.
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 cement provides a stable, shelf-life of at least 18 months, maintains bond strength and mechanical properties, and allows for direct cementation of various dental restorations without pre-treatment, ensuring effective bonding and reduced handling complexity.
Implementation Method 1
a self-cure initiating system comprising of non-amine reducing agent and a thermally stable oxidizing agent
Implementation Method 2
an acidic monomer has to be included in the formulation to render self-etching and self-adhesive capability
Implementation Method 3
Resin cements are variations of filled BIS-GMA resin and other methacrylates. They polymerize through chemically initiated mechanisms
Implementation Method 4
followed by the application of a hydrophilic primer and a bonding agent
Data Source
AI summary
A dental, paste/paste self-adhesive cement includes a polymerizable acidic monomer or monomer mixtures; a polymerizable non-acidic monomer or monomer mixtures, a photo-initiator and/or a co-initiator, a reducing agent such as a benzoylthiourea and other substituted benzoylthiourea, an oxidizing agent, a thermal stabilizer and a glass filler.