The disc that goes into an Xbox 360 is as prone to damage as that of a conventional DVD. Cracks can be caused in the disc from mishandling, an accident or the drive in the Xbox 360 malfunctioning. Replacing the disc can be an expensive proposition, so it might be better to repair the disc so it can continue to be used in the Xbox 360.
Put down the soft lintless cloth. Put the cracked Xbox 360 disc down on the cloth face down. This is so that the cracked side can be seen.
Blow dust off of the exposed side of the cracked Xbox 360 disc with the camel's hair brush.
Squeeze some toothpaste out of the tube and onto the double-layer tissue. Gently rub the tissue onto the exposed side of the cracked Xbox 360 disc.
Continue adding toothpaste to the tissue and rubbing it on the disc until the disc is completely covered in a thin layer of toothpaste.
Pick up the disc in one hand and rub two fingers of the other hand on the disc in a firm up and down motion. Rub all parts of the disc in this fashion until the toothpaste looks smooth all over.
Run warm water in the sink. Take the disc to the sink and hold it under the warm water with one hand while firmly rubbing the disc with two fingers of the other hand in an up and down motion. Rub the disc until the toothpaste layer looks even all over.
Take the disc out from under the warm water and turn the water off. Take a soft, clean cloth and gently wipe the disc dry without touching it with your fingers.
Spray sanitiser on the side of the disc that has the toothpaste applied to it. Rub the sanitiser into the disc using the double-layer tissue and two fingers of one hand in a firm up and down rubbing motion. Let the disc dry.
Setting up the Xbox 360 console so that it sits horizontally can help to keep the disc inside from developing a crack in it. Keeping the Xbox 360 console running cool could help to keep the disc drive from becoming so hot that it damages the disc inside of it. Keep the console cool by running it in a cool environment, having a fan blowing cool air on it and running the console only for short periods of time.
The Xbox 360 disc is composed of a material that develops sharp edges when it breaks. A repair could be temporary and cause the disc to break again. This could lead to severe damage inside of the Xbox 360 and might void the warranty if taken in for a repair to an authorised dealer or Microsoft.