There are several reasons and factors that can cause dark colored gums particularly around the teeth, and these include genetic reasons, medical conditions, medications, dental fillings, bad hygiene and smoking, as noted by iDentalHub. The dark coloration on the gums are made up of melanin, which basically is a type of pigmentation that makes the skin darker as its concentration in the skin increases. While the gums around the teeth have the tendency to turn dark, or may already have been dark in the first place, other parts of the gum such as the area beneath the lips are naturally pink.
Individuals who are genetically dark skin tend to have darker gums, which means that dark gums is not necessarily indicative of poor dental health or a disease. Those who spend more time outdoors, particularly children, are likely to develop darker gums and the dark coloration may be permanent.
Certain diseases such as Addison's disease and Peutz Jegher syndrome causes the gums to turn dark because they stimulate the production of melanin. Diseases that are caused by poor oral hygiene will likely make the gums dark as well. Antimalarial medications, antidepressants and minocycline are also known to cause dark-colored gums. There are several treatment options that can lighten dark colored gums. These treatment include surgical procedures and gum bleaching.