Your cavy does not need any pet store items for his teeth to be in proper size and alignment. Honestly I do not buy any treats from pet stores, because I need to be aware of the sugars, colored ingredients and other components. I recommend fresh hay everyday, it helps with the alignment of teeth and helps their digestive system to work properly and keep clean. Therefore, my advise to you will be to provide you cavy carrots, every 2-3 days, because carrots contain too much vitamin A and it may cause liver problems if provided in an excessive way. You might also want to give your guinea pig some sort of wood for example a little piece of wood from an apple tree, before feeding it to your cavy please wash it and check on it 2-3 times before feeding it to your piggy to make sure there's no bird poop, or any insects, they might hurt your piggy's health.