As in humans, the presence of bacteria causes bad breath (bacteria stinks), and the accumulation of tartar causes irritation and inflammation to the gums around the dog's teeth (gingivitis, under the form of red, swollen gums), which in turn may lead to periodontal disease (the loss of the connective
tissue fibers, ligaments and bone
surrounding the teeth and responsible for supporting them) and eventually tooth loss due to gradual loss of supporting structure — see photo, something known as
gingival recession.