Retainers must be worn long-term in order to keep the teeth in the desired position. Therefore, it is extremely important to keep them clean. Brush your retainer with soap and water every time you brush your teeth. Every so often, you can soak the retainer in a glass of water with a denture-cleaning tablet (Polident or Efferdent work great!). Do not use warm water as it can cause distortion of the appliance.