You will be amazed at how effective the oil is. I put my puffer to sleep every year and "trim" his teeth. It's always a delicate balance between putting him to sleep for a minute versus putting him to sleep forever.
And yes, the oil is commonly used for tooth pain and can be found at Walgreens.
Yes. In the wild, puffers use their teeth to open mollusks, stony corals, etc., and their teeth naturally "wear down" this way. In captivity, the wearing away of tooth structure is limited because their diet is so different. As a result, their teeth continue to grow in length and become so long that it is difficult for them to open their jaws far enough to get food through. This is why his teeth needs to be trimmed back.
You can supply puffers with shelled inverts to eat as well. This will help keep their teeth worn and send Angie in to a tizzy when she sees the puffer going after a snail or hermit crab.