Periodontal Disease More Condition_symptoms Is It Possible For Periodontal Disease To Spread From A Tooth To Another? What Causes Plague To Form On Tooth?

Is it possible for periodontal disease to spread from a tooth to another? What causes plague to form on tooth? - periodontal disease more condition_symptoms

My child regularly brushing their teeth twice a day. In December last year, said the dentist, he has periodontal disease in the gums.
This may be due to its oral hygience not for cleaning kit, if you are willing to work required until the next day. It was about 10 months too late for treatment? Periodontal disease can spread from one tooth to another? It was very unfortunate for him that he had forgiven the disease, the plague of the form on the teeth and gums causes? How to avoid?

Can someone tell please, please, as soon as possible. Thank you very much.