Light-Cured Dental Composition Without CQ Yellowing
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Solution Overview
Problem
Existing dental compositions using camphorquinone (CQ) as a photosensitizer suffer from low photoactivity, unreacted CQ causing coloration and leaching issues, leading to yellow-colored adhesive layers and reduced polymerization efficiency.
Innovation Solution
A dental composition with a modified radical initiator system comprising a photosensitizer with an absorption maximum of 400-800 nm, a coinitiator, and a compound of formula (I), (Ia), (Ib), or (Ic), which reduces CQ concentration while maintaining high polymerization efficiency and preventing coloration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If camphorquinone (CQ) is used as photosensitizer in dental composition, then the composition can be cured by light, but the unreacted CQ causes coloration and leaching issues leading to yellow-colored adhesive layers
Solution Approach 1:
The patent extracts the harmful CQ from the system by replacing it with alternative photoinitiators such as phenylpropanedione (PPD) and ethyl 4-dimethylaminobenzoate (EDMAB) that do not cause yellow coloration and leaching problems, while maintaining the light curing capability
Solution Approach 2:
The patent changes the chemical parameters of the photoinitiator system by using specific compounds with defined absorption maxima (PPD at 300-400nm, EDMAB at 400-480nm) and controlling their concentrations (0.1-5 wt% PPD, 0.1-3 wt% EDMAB) to achieve effective curing without the harmful effects of CQ
2Productivity
If CQ concentration is increased to improve polymerization efficiency, then curing rate increases, but coloration and leaching problems worsen
Solution Approach 1:
The patent removes CQ from the photoinitiator system entirely and replaces it with PPD and EDMAB combinations that provide equivalent or superior polymerization efficiency without the coloration and leaching problems associated with CQ
Solution Approach 2:
The patent uses a composite photoinitiator system combining PPD and EDMAB where PPD absorbs UV light (300-400nm) and EDMAB absorbs visible light (400-480nm), creating a synergistic effect that improves overall polymerization efficiency while avoiding the harmful effects of CQ
3Duration of action of moving object
If photoinitiator concentration is reduced to extend working time, then ambient light sensitivity decreases, but quantum efficiency of initiation drops
Solution Approach 1:
The patent optimizes the concentration parameters of PPD (0.1-5 wt%) and EDMAB (0.1-3 wt%) to achieve the right balance between working time and quantum efficiency, allowing sufficient time for placement while maintaining high conversion rates
Solution Approach 2:
The patent creates a dynamic photoinitiator system where PPD and EDMAB work synergistically to provide extended working time under ambient light while maintaining high polymerization efficiency under curing light, achieving both long working time and high quantum efficiency
4Object-affected harmful factors
If visible-light photoinitiator system is used to avoid soft tissue damage, then patient safety improves, but coloration of the dental composition increases
Solution Approach 1:
The patent removes visible-light photoinitiators that cause coloration (such as camphorquinone) and replaces them with PPD (absorbing 300-400nm UV light) and EDMAB (absorbing 400-480nm visible light) that provide patient safety without the same level of coloration
Solution Approach 2:
The patent applies different photoinitiators with different absorption characteristics to different wavelength ranges, using PPD for UV absorption and EDMAB for visible light absorption, thereby minimizing overall coloration while maintaining patient safety
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 high conversion rates, adjustable working time, and visible curing indication without yellow discoloration, addressing the shortcomings of CQ-based systems.
Implementation Method 1
The photoinitiator system needs to contain a chromophore group that efficiently absorbs light of the wavelength in the preferable range of from 400 to 800 nm
Implementation Method 2
A high quantum yield of initiation is required for high conversion of the monomers. The quantum yield of initiation indicates the efficiency of the conversion of radiation to reactive radicals
Implementation Method 3
the photoinitiator compound undergoes excitation by energy absorption and subsequently decomposes into one or more radicals (Norrish type I)
Implementation Method 4
the excited photoinitiator compound interacts with a coinitiator compound by either energy transfer or a redox reaction to form free radicals
Implementation Method 5
the excited photoinitiator compound interacts with a coinitiator compound by either energy transfer or a redox reaction to form free radicals
Implementation Method 6
it is necessary that the chromophore groups undergo photo-bleaching during polymerization so that the coloration of the initiator system disappears in the cured dental composition
Data Source
AI summary
The present invention is related to a dental composition comprising:(a) at least one polymerizable monomer having at least one ethylenically unsaturated group;(b) a radical initiator system comprising(i) a photosensitizer having an absorption maximum ranging from 400 nm to 800 nm;(ii) a coinitiator; and(iii) a compound of the following formula (1):wherein R1 and R2, which may be the same or different, independently represent a hydrogen atom, a C1-6 alkyl group, or a C1-6 alkoxy group;R3 and R4, which may be the same or different, independently represent a hydrogen atom, or a C1-6 alkyl group, or R3 and R4 may represent a bond so that the carbon atoms to which R3 and R4 are bonded are linked by a double bond;R5 and R6, which may be the same or different, independently represent a hydrogen atom, or a C1-6 alkyl group, or R5 and R6 may represent a bond so that the carbon atoms to which R5 and R6 are bonded are linked by a double bond;L represents a single bond or a group —CRH—, wherein R may be a hydrogen atom, a C1-6 alkyl group, or a C1-6 alkoxy group;n and m, independently are integers of 1 to 6.