Hey hi, yes you absolutely need to cover that hole to stop food accumulation and further decay. Please don't worry about the heavy saliva flow; dentists have very easy corporate tools to handle exactly this problem!
We have Saliva ejectors, rubber dam,biteblocks
Next Steps
Go visit your dentist soon. Tell them beforehand about your high saliva flow and request them to use a rubber dam or high-vacuum suction. They will easily re-fill the cavity with a strong, permanent tooth-colored filling material!
Health Tips
Immediate treatment required.Maintain oral hygiene by brushing twice daily...if u have any problem with the odour of ur mouth because of cavities use oral mouthwash