Rodent incisors and grass

Incisors are used for biting and cutting food. This is required for animals that predominantly eat a fibrous diet. Yes, molars are needed to chew the food, but the incisors allow for the initial cutting.

The reason they don't stop growing is because unlike our teeth, their incisors don’t have roots. To keep them from growing into their brains, rodents grind their teeth against each other. This self-sharpening not only keeps the teeth short, but it also keeps the edges very sharp, almost like a chisel.

* Also, rabbits are not rodents, as some people assume them to be

Wikipedia says: Ruminating animals have various physiological features that enable them to survive in nature. One feature of ruminants is their continuously growing teeth. During grazing, the silica content in forage causes abrasion of the teeth. This is compensated for by continuous tooth growth throughout the ruminant's life, as opposed to humans or other nonruminants, whose teeth stop growing after a particular age. Most ruminants do not have upper incisors; instead, they have a thick dental pad to thoroughly chew plant-based food.

I didnt know that

Neither did I, I think I'll write a blog post out of this

I think it means this: https://en.wikipedia.org/wiki/Hypsodont

Yes, you're right. Rabbits, guinea pigs, chinchillas and degus have aradicular hypsodont teeth. The incisors of all rodents are aradicular hypsodont, while the cheek teeth are either aradicular hypsodont or brachyodont depending on the species. The aradicular hypsodont tooth never forms a true root with an apex and the tooth grows continuously throughout the animal’s life. I make that clear in the blog post I wrote just now.

https://biology-forums.com/index.php?article=1662.0