What is the ruling on joining separated teeth, especially since leaving them may affect one's health?

The Prophet, may Allah’s prayers and peace be upon him, cursed women who practice tattooing, those who have their eyebrows plucked, and those who have their teeth filed for beauty, altering Allah’s creation. It is understood from his saying "for beauty" that what is condemned is alteration done to seek beauty. However, if it is for a necessity, such as medical treatment, then it is permissible. Accordingly, if damage results from gaps between the teeth, it is permissible to treat them. But if it is merely for the sake of seeking beauty, then it is not permissible.