There are no hard and fast rules but ZQuiet should last for many months. However, the manufacturer suggests replacing the device with a fresh one every 4-6 months. If you clench or grind your teeth during the night, it may reduce the device's length of service. It could fail after only three months. Fortunately, the manufacturer has accounted for this and also produces a second version (ZQuiet Firm) that has an extra-strong hinge. If you experience premature hinge failure, it's best to choose this option when you order again.