Periodontitis is an inflammatory disease caused by bacterial plaque. Untreated, it could damage oral structures beneath the gum line. The gum line draws back only with advanced periodontitis, and when the tooth roots are exposed, this may be mistaken for receding gums.
However, gum recession is not always caused by periodontitis. Too vigorous tooth brushing is another reason. Gum recession is not reversible even if you change your oral hygiene habits. Only a dental examination can reveal the exact cause.