Thank you for your query at DoctorSpring.com
A coated tongue isn't a disease and isn't usually a sign of anything serious.
A coated or white tongue occurs when the surface is colonised by bacteria or fungi
It's usually only temporary.You can try gently brushing it with a tongue scraper and drinking plenty of water to help it improve.
However, sometimes a coated tongue can indicate an infection or more serious condition.
If you have symptoms like burning, etc then it could be associated with problems such as leukoplakia, lichen planus or oral thrush- which should be shown to a oral surgeon for further investigations/treatment.
If there are no symptoms regular cleaning with toothbrush (preferable) or with motorised toothbrush is advisable.
Feel free to discuss further,
Orthodontist and Clear Aligner Specialist(Germany)