Amalgam tattoos are very common, as a small particulate of the silver filling material becomes embedded in the soft tissues of the mouth and gradually they discolor a sport surrounding the metal particle. This can happen at the time of placement of the filling, appearing later in life, or can come as a filling begins to break down as it ages. I assure you they are not BS. Things that look like amalgam tattoos are usually oral melanomas, a very deadly form of oral cancer but thankfully very rare. (You can read more about these on the facts page.) While the biopsy will give you a definitive answer what you wish to be hoping for right now is an amalgam tattoo. The causes of oral melanomas, the only oral cancer that looks generally like an amalgam tattoo are relatively unknown. They are not directly related to tobacco use such as the squamous cell carcinomas that the bulk of the posters here on the boards have had. While an unlikely source of a melanoma, I agree with Gary that this should be a wake up call to a dangerous lifestyle choice.