Orthodontic Ligating Member Retention Force Optimization
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Solution Overview
Problem
Conventional self-ligating orthodontic brackets experience a significant reduction in retention force after a limited number of opening and closing cycles, leading to inefficiency and potential disengagement of the archwire, due to excessive wear and misuse by patients.
Innovation Solution
A ligating member with an improved geometry, featuring a latching element and offset ligation fingers, is designed to maintain effective retention force over a greater number of cycles, utilizing materials like 17-4 stainless steel and incorporating a guide and stiffener for enhanced durability and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional ligating slide is designed to optimize retention force for a short life-cycle, then the retention force is high initially, but the retention force reduces significantly after a limited number of opening/closing cycles
Solution Approach 1:
The patent changes the geometric parameters of the latching element, specifically the ratio between the deflection length (L1) and the distance from the tip to the narrowest region (L2), where L2/L1 is between 0.40 and 0.60. This parameter optimization allows the latching element to maintain consistent retention force over thousands of cycles by distributing stress more effectively during repeated opening and closing operations.
Solution Approach 2:
The latching element is designed with specific dynamic characteristics including a deflection length L1 of at least 0.020 inches and a narrowest region with cross-sectional dimensions of no more than 0.010 inches by 0.020 inches. These dynamic properties enable the element to flex and return reliably through thousands of cycles while maintaining retention force.
2Reliability
If the ligating slide is cycled multiple times during treatment or if patients play with the bracket, then the retention force decreases, but the structure becomes more durable
Solution Approach 1:
The patent applies local quality by creating a specific narrowest region in the latching element with precise cross-sectional dimensions (no more than 0.010 inches by 0.020 inches) located at a specific position (L2 distance from the tip). This localized geometric feature concentrates the flexing action at the optimal point, allowing the rest of the structure to remain simple while achieving reliable performance through thousands of cycles.
3Ease of operation
If the retention force becomes too low, then the ligating member can be operated easily, but the archwire may disengage from the bracket
Solution Approach 1:
The latching element is pre-designed with specific geometric parameters (deflection length L1 ≥ 0.020 inches, narrowest region dimensions ≤ 0.010 inches by 0.020 inches, and L2/L1 ratio between 0.40 and 0.60) that establish the optimal balance between ease of operation and archwire retention before the bracket is even used. This preliminary optimization ensures reliable performance throughout the intended lifecycle.
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 ligating member maintains consistent retention force, reducing the likelihood of archwire disengagement and extending the lifespan of the orthodontic bracket, while allowing for efficient tooth movement and reduced treatment time.
Implementation Method 1
The latching element includes a head portion and a neck portion extending from the base. The neck portion has a deflection length (L1) measuring at least 0.020 inches and a narrowest region having cross-sectional dimensions of no more than 0.010 inches by 0.020 inches. The ratio (L2/L1) of the distance (L2) from the tip of the latching element to the narrowest region of the neck portion to the deflection length (L1) is between 0.40 and 0.60.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A ligating member (400) operable to retain an archwire (700) within a slot (26) of an orthodontic bracket (10) or buccal tube, including a base (402), a first ligation finger (410) extending from the base, a second ligation finger (412) extending from the base, and a latching element (404) extending from the base between the first ligation finger and the second ligation finger. The latching element includes a neck portion (408) extending from the base, the neck portion having a minimum cross-section region, and a head portion (406) extending from the neck portion, the head portion including a protrusion (416). The ligating member has a length, L1, from the base to a centerline of the protrusion, and a length, L2, from a centerline of the minimum cross-section region to the centerline of the protrusion, wherein L2 is equal to or greater than 40% of L1.