Light Curable Dental Composition Refractive Index Matching
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Solution Overview
Problem
Current light curable compositions for dental filling and restoring materials face challenges in achieving deep curing depth and aesthetic harmony with natural teeth, particularly in posterior teeth, due to issues like polymerization shrinkage, bubble inclusion, and mismatched refractive indices leading to poor translucency and light diffusivity.
Innovation Solution
A light curable composition comprising a polymerizable monomer, an inorganic filler with an average particle size of 0.07 µm or more, and an organic-inorganic composite filler with an average particle size of 0.5 µm or more, where the refractive indices of the inorganic filler and composite filler are carefully selected to be close to the polymerizable monomer's refractive index, ensuring deep curing depth and translucency matching natural teeth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a light curable composition is applied to a cavity at a stroke and polymerized by photoirradiation, then the treatment time is reduced, but detachment occurs at the bottom or margin due to polymerization shrinkage and polymerization failure
Solution Approach 1:
The patent applies segmentation by using multiple photopolymerization initiators with different absorption characteristics to enable staged polymerization. The first initiator (maximizing absorption at 480-520 nm) enables initial curing, while the second initiator (maximizing absorption at 600-700 nm) completes polymerization in previously uncured regions, particularly at the bottom and margins of deep cavities, preventing detachment and polymerization failure.
2Reliability
If a light curable composition is applied to a cavity little by little and polymerized and cured every time, then polymerization shrinkage is reduced, but time and effort are required and bubbles may be included in the interface between layers
Solution Approach 1:
The patent implements continuity of useful action through dual photopolymerization initiators that enable continuous polymerization throughout the material. The first initiator starts polymerization throughout the composition, and the second initiator continues polymerization in regions where the first initiator was less effective, eliminating the need for multiple incremental applications while preventing bubble inclusion by maintaining continuous polymerization action.
3Length of stationary object
If the refractive index of inorganic filler is matched to the polymerizable monomer, then deep curing depth is achieved, but the appearance of the cured body does not harmonize with natural teeth
Solution Approach 1:
The patent applies local quality by using inorganic fillers with refractive indices specifically optimized for deep cavity applications (1.50-1.70), which may differ from natural tooth refractive indices. This creates a material optimized for the specific local condition of deep cavity restoration, achieving adequate curing depth while the overall aesthetic appearance is maintained through the composite resin formulation and color matching capabilities.
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 allows for effective polymerization and curing in deep cavities with a single or few applications, achieving high light permeability, translucency, and aesthetic harmony with natural teeth, while maintaining mechanical strength and preventing secondary caries.
Implementation Method 1
a light curable composition prepared by mixing a polymerizable monomer with large amounts of an inorganic filler and a photopolymerization initiator... irradiated with active light using a special light irradiator for polymerization and curing
Data Source
AI summary
According to the present invention, a photocurable composition is provided, which is characterized by comprising a polymerizable monomer component (A), an inorganic filler component (B) having an average particle diameter of 0.07 µm or more, an organic-inorganic composite filler component (C) comprising an inorganic filler component (C1) and an organic polymer component (C2) and having an average particle diameter of 0.5 µm or more, and a photopolymerization initiator (D), wherein the inorganic filler component (B) and the organic-inorganic composite filler component (C) are contained in a total amount of 100 to 1500 parts by mass relative to 100 parts by mass of the polymerizable monomer component (A), and the polymerizable monomer component (A), 90 parts by mass or more of the inorganic filler component (B) and 90 parts by mass or more of the organic-inorganic composite filler component (C) are selected in such a manner that specific requirements can be satisfied.