I went to the dentist as my gums are receding and he told me my gums are healthy so not to worry. how are they healthy?

Progression.: Progression of recession is what important. Are your gum continue to recede time after time? Dentist usually should make a note of the position of the gum line and follow up after 2-3 months or even 6 months to confirm the diagnosis. Continuing recession is a concern and should be treated for underlying cause before gum grafting procedure. Static recession can be watched.

Receding gums: "receding gums" may be caused by many things, gum disease, improper dental restoration, extraction of teeth, clenching or grinding to name a few. If your gums are tight around the teeth and pinkish in color and no pocket probings exceed 3-4mm and they do not bleed when probed whether the gums are at the enamel margin or 4-5mm below it the soft tissue is healthy. Maintenance is the key!

See Periodontist: While everything may appear healthy there has to be a reason for your gum recession. Gums don't recede unless there's a reason. It may be a systemic problem, reaction to medication, improper brushing, malocclusion, clenching/grinding, or one of many other factors. Time to see a gum specialist, a periodontist, to determine why the recession and if any treatment is indicated. Don't wait.

Gum recession: Let's explain it this way. Is it an ideal or perfect situation? No. Different if 20 or 70 years old. If the gums are light pink, flat, not bleeding, minimal pocket depth, no clefts, and adequate attached gingiva, then the gums are considered healthy. If rapidly receding, inflamed, red, bleeding, deep pockets, clefts, significant loss of attached gingiva, then it's not healthy. It's all relative.