Thank you for waiting. The situation is urgent because when a guinea pig doesn't eat for any reason, it is extremely serious. It is called anorexia. If they go for 24 hours without eating, a condition called ketosis develops and the guinea pig cannot recover.
Until the teeth grow back, you can feed Kai from a syringe. Make a slurry of crushed pellets, water, and pureed vegetables. This can be more difficult than it sounds, so I'm giving you a link to a page that describes it in great detail, including variations on what to feed, and how often to feed:
There is a product called Oxbow Critical Care, available in pet stores, that would be even better than the homemade slurry. Many guinea pigs like the taste and will lap it up from a dish. It would also be good to give your guinea pig some Pedialyte (made for human infants), which you can buy in drug stores, discount stores, and many supermarkets.
It's possible that whatever accident broke Kai's teeth also caused pain in his jaw. There could even be a broken bone there. If you think that is possible, it would be best to see a vet. Here is a directory of guinea pig vets:
If Kai is otherwise healthy and the jaw isn't damaged, the teeth should grow back fairly quickly - 3 to 6 weeks. In the meantime, make sure he gets nourishment form a slurry. Here is where you can read more about broken teeth in guinea pigs:
If you have more questions, just let me know. I hope Kai will be fine.
My goal is to provide you with excellent 5 star service – if you feel you have gotten anything less, please reply back, I am happy to address follow-up questions. Please remember to rate my service after you have all the information you need. I will greatly appreciate a positive rating as that is the only way I am compensated. Thank you!