You are likely to need a nightguard replacement. Generally the more extreme the condition the more likely you will need to replace your nightguard. If the underlying causes of the clenching and grinding are eliminated, you may never need another nightguard. This excessive muscle activity and damage to the teeth and facial structures may be caused from psychological stresses, a problem with the bite (dental occlusion), and sometimes a sleep breathing disorder or a combination of these factors. For most people these causes can not be completely eliminated and they may find that they need to replace their nightguard within six months while others see their nightguard last as long as five years. Soft nightguards which are very comfortable but may only last a short time due to their composition and inability to withstand extreme clenching forces. The harder materials of some nightguards require careful fitting (often from a dentist) and may last longer. Changes in your mouth from dental work may not allow the nightguard to fit properly requiring replacement.