Dental Compositions with Addition-Fragmentation Agents
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Solution Overview
Problem
Current dental compositions face challenges in reducing stress deflection and shrinkage while maintaining sufficient mechanical properties and depth of cure, leading to potential clinical issues such as decreased restoration longevity and postoperative sensitivity.
Innovation Solution
A dental composition incorporating an addition-fragmentation agent with ethylenically unsaturated terminal groups and an α, β-unsaturated carbonyl backbone, along with inorganic oxide filler, which is free-radically cleavable, is used to reduce polymerization-induced stresses and provide improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hardenable dental compositions are used, then sufficient mechanical properties and depth of cure are achieved, but stress deflection and shrinkage are high leading to decreased restoration longevity and postoperative sensitivity
Solution Approach 1:
The patent changes the chemical composition parameters of the dental material by incorporating specific addition-fragmentation agents with defined molecular structures (formula I) containing ethylenically unsaturated terminal groups and α,β-unsaturated carbonyl backbones. This chemical parameter change enables reduced stress deflection while maintaining mechanical properties and depth of cure, thereby improving restoration longevity.
Solution Approach 2:
The patent creates a composite dental composition by combining the addition-fragmentation agent (formula I) with at least one monomer having ethylenically unsaturated groups and inorganic oxide filler. This composite material approach allows the system to achieve reduced stress deflection and shrinkage while maintaining sufficient mechanical properties through the synergistic interaction of components.
2Strength
If conventional hardenable dental compositions are used, then sufficient mechanical properties are achieved, but polymerization-induced stresses cause postoperative sensitivity
Solution Approach 1:
The patent modifies the chemical parameters of the dental composition by introducing addition-fragmentation agents with specific molecular structures (formula I) that undergo controlled polymerization. This parameter change reduces polymerization-induced stresses while maintaining mechanical strength, thereby minimizing postoperative sensitivity.
Solution Approach 2:
The patent converts the potentially harmful polymerization-induced stresses into beneficial effects by using addition-fragmentation agents that undergo controlled fragmentation during polymerization. This process reduces internal stresses and improves adaptability to tooth structures, transforming a harmful effect into a beneficial one that reduces postoperative sensitivity.
3Reliability
If addition-fragmentation agents are introduced to reduce stress deflection, then restoration longevity is improved, but composition complexity increases
Solution Approach 1:
The patent addresses composition complexity by defining specific parameter ranges for the addition-fragmentation agent (formula I), including constraints on molecular weight, functional group composition, and stoichiometric ratios. These parameter specifications provide guidance for formulation while maintaining the beneficial stress-reduction effects that improve restoration longevity.
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 composition achieves reduced stress deflection and shrinkage, enhancing the longevity of dental restorations and minimizing postoperative sensitivity by effectively managing polymerization-induced stresses, while maintaining adequate mechanical properties and depth of cure.
Implementation Method 1
an addition-fragmentation agent comprising at least one ethylenically unsaturated terminal group and a backbone unit comprising an α, β-unsaturated carbonyl wherein the addition-fragmentation agent has formula I; at least one monomer comprising at least two ethylenically unsaturated group
Implementation Method 2
addition-fragmentation agent comprising at least one ethylenically unsaturated terminal group and a backbone unit comprising an α, β-unsaturated carbonyl wherein the addition-fragmentation agent has formula I
Data Source
Figure 1~2
AI summary
Dental compositions are described comprising an addition-fragmentation agent comprising at least one ethylenically unsaturated terminal group and a backbone unit comprising an a, ß- unsaturated carbonyl; at least one monomer comprising at least two ethylenically unsaturated group; and inorganic oxide filler. The addition-fragmentation agent is preferably free-radically cleavable. The addition-fragmentation agent preferably comprises at least two ethylenically unsaturated terminal groups, such as (meth)acrylate groups. In some embodiments, the addition-fragmentation agent has the formula (I) wherein R1, R2 and R3 are each independently Zm-Q-, a (hetero)alkyl group or a (hetero)aryl group with the proviso that at least one of R1, R2 and R3 is Zm-Q-; Q is a linking group have a valence of m +1; Z is an ethylenically unsaturated polymerizable group; m is 1 to 6; each X1 is independently -O- or -NR4-, where R4 is H or C1-C4 alkyl; and n is 0 or 1. Also described are dental articles prepared from a dental composition comprising an addition-fragmentation agent and methods of treating a tooth surface are described.