Most likely, black patterns on the roof of a cat’s mouth are nothing more than normal coloration. As cats mature, they may develop black pigment spots on their lips and gums. According to About.com, the lips and gums of a healthy cat may be pink, black, or both.
According to Cat Channel veterinarian J. Veronika Kiklevich, there are various indications that the black marks are harmless. For instance, if the mark is on the tissue beneath the teeth rather than the tooth itself, it is unlikely to indicate tooth injury. Similarly to people, the black marking should be flat; if it is elevated, this is cause for concern. Similarly, the region surrounding the black spot should not be red, inflamed, or prone to bleeding. Lastly, if the marking remains unchanged in size, it is likely a pigmented patch, similar to the cat’s fur markings.
Any significant changes in the teeth or gums of a cat should be evaluated by a veterinarian. This includes if they get inflamed, lose colour, or turn very bright pink, particularly if this is followed by a worsening of the cat’s breath odour.