>>213143825
Kek. Congenitally missing 4 premolars is rare obviously.
>>213143864
Drink water, chew gum, don't sleep in dry or hot rooms. You can also take some OTC to help. Check what meds or supplements you're using. If you have chronic xerostomia get some tests done. I'd start with full bloods and sialometry. However, if you had that problem I'd expect you'd have been referred by now.