Orthodontic Springs: Design, Properties, and Clinical Use

Essential Requisites of an Orthodontic Spring

• 1. Simple to fabricate
• 2. Easy to adjust
• 3. Should fit into the available space
• 4. Easy to clean
• 5. Should apply force of required magnitude and direction
• 6. Should not slip or distort when placed over a sloping surface
• 7. Should remain active over a longer period of time

Mechanical Properties of Orthodontic Wire

• 1. Stress: It is defined as force per unit area.
• 2. Strain: Change in length per unit length.
• 3. Proportional Limit: It is defined as the greatest amount of stress where stress is proportional to strain.

Finger Spring for Mesial and Distal Movement

Indications and Material

• 1. Use: For mesial and distal movement which are in the line of the arch.
• 2. Material: Made of 0.5 mm stainless steel (s/s) wire.

Components and Dimensions

• 3. Parts:
• 4. Active arm: 12–15 mm long
• 5. Retentive arm: 4–5 mm long
• 6. Coil: 3 mm of inner diameter

Placement and Activation

7. Placement: The coil should be placed along the long axis of the tooth, perpendicular to the direction of movement and opposite to the intended tooth movement. 8. Preparation: Prior to acrylization, it should be boxed so it lies in a recess between the mucosa and the base plate. 9. Activation: By opening the coil to about 3 mm.

Double Cantilever Spring

Uses and Indications

• 1. Uses: For palatally positioned teeth.
• 2. For teeth in crossbite.
• 2. For minor rotations.

Specifications and Components

• 3. Material: Made of 0.5 mm stainless steel (s/s) wire.
• 4. Parts:
• Active arm: 10–12 mm long
• 5. Retentive arm: 2–3 mm long
• 6. Coil: 2–3 mm internal diameter

Activation Method

7. Activation: By opening the coil to about 2–3 mm.

T-Spring (Club Spring)

Indications and Design

1. Nomenclature: Also called a Club spring because of its resemblance. It is used to move the premolar and molar buccally when they are palatally blocked. 2. Material: Made of 0.5 mm wire. 3. Stiffness: Because it gets embedded in the acrylic, it becomes more stiff. 4. Structure: It has two parts.

Components and Adjustment Loops

• 5. A horizontal part
• 6. A vertical part
• 7. Adjustment Loops: It has two adjustment loops. 8. Use of adjustment loops: To increase the length of the wire after its activation.

Activation Method

9. Activation: By stretching the spring at a 45-degree angle to the long axis of the tooth.

Coffin Spring

1. History: Introduced by Walter Coffin in the year 1881. 2. Material: Made of 1.25 mm stainless steel (s/s) wire. 3. Indications: For slow expansion and 4. for crossbite correction. Advantage: The advantage over a screw is that it produces differential expansion.

Activation Techniques

• 1. By opening the loop 1–2 mm.
• 2. By stretching the ends of the wire.