GAC Open Coil Spring
Open, or compression, coils are 15mm in length when passive and may be compressed to 3mm. Between these points, the coil will exert 50 (extra light), 100 (light), 150 (medium), 200 (heavy), or 250 (extra heavy) , and 300 (XX Heavy) grams of force until 14mm, and then the force falls to 0 as it becomes passive again. No distortion will occur during movement. These low forces limit patient discomfort and ensure good circulation in the periodontal pocket during movement. Typically, you will see 4mm of space opened in three months (this varies depending on the age and health of the patient).
To engage the open coils, mark the archwire where the mesial and distal tooth destinations are located. Crimp on the mesial stop and ligate the archwire up to the point where the spring is to be placed. Slide the coil over the archwire and crimp on the distal stops. Ligate the balance of the wire. Since the Sentalloy coil needs about 1/10 as much wire as steel, good hygiene is much easier, but do advise the patient to rinse and brush around the coil. No other adjustment is needed.