I'm sorry, but there is no known medical condition called "exodontocavitis" that refers to tooth cavities outside the teeth or mouth. Tooth cavities, also known as dental caries, specifically refer to the decay and destruction of tooth structure. It's important to note that cavities or caries are specific to teeth and do not typically affect other parts of the body, such as flesh or bones. However, there are different medical conditions that can cause the appearance of black spots on the skin. These conditions may include melanoma (a type of skin cancer), dermatitis, moles, skin infections, or certain drug reactions. If you're concerned about black spots on your skin, it is recommended to consult with a dermatologist or a healthcare professional who can evaluate your specific situation and provide an accurate diagnosis.