Orthodontic Adhesive Quaternary Curing System
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Solution Overview
Problem
Current orthodontic adhesives have limitations in their working to curing (W/C) ratios, leading to compromised bond strength and increased risk of bond failure due to short working times and long curing times, which can result in delayed or incomplete bonding procedures.
Innovation Solution
Development of orthodontic adhesive compositions with a quaternary curing initiator system comprising camphorquinone, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, octyldimethylaminobenzoate, and 1,1'-azobis(cyanocyclohexane, along with a filler and optional colorant, to achieve extended working times and reduced curing times, thereby enhancing the W/C ratio to at least 10, 12, or 14.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional light-curable adhesives are used, then curing speed is improved, but working time is insufficient leading to compromised bond strength
Solution Approach 1:
The initiator system is segmented into multiple components (camphorquinone, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and 1,1'-azobis(cyanocyclohexane)) that perform different functions: camphorquinone provides slow initiation for extended working time, while the phosphine oxide and azo compound provide rapid curing when activated by light. This segmentation allows the adhesive to maintain both long working time and fast curing capability.
Solution Approach 2:
The patent changes the chemical parameters of the initiator system by introducing a quaternary system with specific concentrations of each component. The camphorquinone concentration is optimized for extended working time under ambient lighting, while the phosphine oxide and azo compound concentrations are tuned to provide rapid polymerization when exposed to curing light, achieving a W/C ratio of at least 10.
2Device complexity
If conventional binary or ternary initiator systems are used, then formulation simplicity is maintained, but W/C ratio is limited to approximately 2
Solution Approach 1:
The patent creates a composite initiator system combining four components with complementary properties: camphorquinone (sensitizer), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (electron donor), and 1,1'-azobis(cyanocyclohexane) (catalyst). This composite initiator system achieves a W/C ratio of at least 10, representing a tenfold improvement over conventional binary or ternary systems while maintaining practical formulation complexity.
3Ease of operation
If longer working time is achieved, then bracket positioning flexibility is improved, but curing time increases leading to reduced productivity
Solution Approach 1:
The adhesive exhibits periodic action in its polymerization process: initially slow polymerization under ambient lighting allows extended working time for bracket positioning (first period), then rapid polymerization when exposed to curing light completes the bond quickly (second period). This periodic behavior enables both bracket positioning flexibility and high productivity, with W/C ratio of at least 10.
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 improved W/C ratios result in higher bond strength and durability, allowing for more efficient and successful orthodontic procedures with reduced patient discomfort and clinic time, as well as enhanced impact toughness and flexibility of the adhesive.
Implementation Method 1
Light-curable adhesives are most popular due to their single-component nature
Implementation Method 2
Some currently available adhesives utilize binary-type (2-component) initiator systems consisting of a sensitizer and an electron donor
Data Source
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AI summary
An orthodontic adhesive includes a curable resin monomer component; a quaternary curing initiator system; and filler. Another orthodontic adhesive having a W/C ratio (working time to curing time ratio) of at least 10, 12, 14 or 20, includes a curable resin monomer component; a curing initiator system; and filler. The adhesives are suitable as light-curing and may include a colorant. Suitable colorants include reversible, thermochromic dyes. The adhesive may also include a resin toughening component.