I hope you find what you are looking for but I can tell you this much. Meth mouth can be assumed, but not certain. The reason being that 2 things cause meth mouth...and neither is really the meth.
1. Sugar cravings associated with meth use - and subsequent eating of such foods or drinks
2. Lack of oral care in combination with the sugar diet.
Meth mouth looks just like Mountain Dew Mouth with poor oral hygiene so a photo isn't diagnostic.
I guess what I'm saying is he could be addicted to meth, or he could be addicted to mountain dew and the internet
Good luck.