I can't speak about periodontitis but my gums used to bleed and were receding due to years of poor oral hygiene and nicotine use. What helped me was:
1. Brushing and flossing twice a day
2. Eating more protein and red meats
3. Cutting out refined sugar and limiting natural sugars to a smaller amount
4. Salt water rinse
5. Oil pulling
6. Quit nicotine use if you smoke, chew, etc. This really does a lot of damage and will stain your teeth and cause gums to recede
Hope this helps!
Hail Satan