you should take them to the vet once every while to have their teeth checked. The ones you cannot see at the back can overgrow and make your piggies ill. when i was younger and didnt know i had two piggies die from overgrown teeth.
I do it myself but some people struggle so take them to the vets to have their nails clipped. its really easy anyway but if you dont feel comfortavle with it, let the vet do it.
Also always check their weight as this is be a good indication that something may be wrong with your piggie if they start to lose weight.
Keep an eye on their fur and skin, checking for lice/ mites/ fungal infections, and all should be fine!