Hmm, I never heard anything about what it can do to teeth. I was on Tigicyline from August 09 to beginning of October 09. Never noticed anything with my teeth. My main side effect was nausea, especially after the first dose b/c they double the first day and it took me a while to recover.I actually was on Zofran along w/ the drug, but I was also kinda low in weight and abx affect more when I am lower in weight. The other downfall for me was the mixing bag, was a real bugger, but not sure if it is the same for everyone.
Admittedly I do not have "great" teeth to begin with, because I was stupid in high school I didnt take great care with brushing 2 times a day and from that and treatments w/ things like TOBI that stick to your teeth and especially gum lines. I didnt have a dentist until I got to college as well. Now I use fluoride toothpaste and/or ACT mouthrinse or prescribed gels they give me after brushing at night.
As if it yellows, maybe try the white strips? Also if he is only 7 doesnt he have a few more baby teeth to lose?
Good Luck with your son, I am sorry he has to use such potent abx so young.