Oral health runs on two slow-motion bacterial diseases. Tooth decay is chemistry: mouth bacteria ferment sugar into acid, acid dissolves enamel, and the tug-of-war between dissolving and repair (saliva and fluoride fight for repair) decides whether a cavity forms. Gum disease is immunology: plaque along the gumline triggers inflammation that, unchecked, destroys the ligament and bone holding teeth — nearly half of adults over 30 have some of it, and it is the leading cause of tooth loss in adults.
Neither is a hygiene morality tale alone. Genetics, saliva, diet pattern, smoking, dry-mouth medications and diabetes all tilt the field — the diabetes link runs both directions, with gum inflammation worsening glucose control and vice versa. And both diseases are silent in exactly the stage where they are cheapest to turn around, which is the case for the boring interventions: fluoride, brushing that actually reaches the gumline, cleaning between teeth, and the dental visits that catch what mirrors miss.
The supplement industry has discovered this territory — oral probiotics, "tooth and gum" formulas, dissolving candies with health claims. The guides here explain the diseases first; the ingredient and product pages then grade the aisle's claims against trials, which are fewer and smaller than the marketing suggests.