I experience excessive salivation during night , i had dental procedures recently but this problem exists a long ago?

Irrelevant: to your dental procedure. Excessive saliva can be caused by either an increase in your body's production of saliva or a decrease in your ability to swallow saliva. Causes of increased saliva are : medication (e.g. Klonopin), gastroesophageal reflux disease or pregnancy or oral infection. See your PCP for evaluatin and dignosis.

Not Unusual: Some people have this situation and it is only an inconvenience and not a problem.

Medication: You need to see an oral surgeon to determine the cause of the excess salivation. There are medications that reduce salivary flow, but they are not to be used long term