Never thought I would say I'm glad to hear a drug addict is in jail, but I am in this case. Let's face it, he doesn't want rehab. He doesn't want to quit. He likes his highs.
At least in jail, he's not helping his friends scheme to steal your family's belongings. He's not manipulating you to help him get drugs. He's certainly not helping a 15 YO get and use drugs.
For now, jail is the best place for him. He's relatively safe, probably not using and not helping minors use. Maybe he'll do some thinking and realize that he needs to change his life.
by the way, I'd be talking to the mom of the 15YO and thanking her for being concerned enough to put a stop to having your son help hers use. It takes courage to report someone. I'm sure her son is very angry with her and I bet she would appreciate knowing you understand and don't blame her.
Be strong. We know his tooth is going to hurt. We also know they aren't going to do anything there unless it abscesses and his jaw swells. So, he is going to have to suffer and you are going to have to accept that he will suffer. Bailing him out so he can go to the dentist won't work. Odds are the bail money would have been the dentist's money are pretty good. So, even if he is bailed out, you still won't have the funds to pay to have the tooth removed. BUT you know he'll be safe and not using and that is actually more important right now.
You can do this. HUGS!!!!