Thanks for query,
Our salivary glands produce approximately one to two quarts of saliva every day. Since we typically swallow continuously we usually don't notice it.
The reason that we notice excess saliva is because we either are not swallowing enough or because our salivary glands are producing more saliva that usual.
The other condition like pregnancy
,new dentures.certain medication,may cause this problem.
preparation taken under medical supervision may solve your problem temporary.