Sulfatrim is basically the adult version of Septrin, that is banana flavoured and used in paediatrics.
It is double the strength of Septrin, unflavoured and is an antibiotic prescribed for a range of different bacterial infections.
What was this prescribed for, if at all?
As for the dental, you can ask your vet more about the procedure, yes as they are small animals they can be more susceptible to things going wrong than say a 30lbs dog but many vets use a reversible sedative which means if your boy starts to not cope they can reverse what they have done.
My granny owned pigs for as long as I can remember and many of them came to her with dental issues which were sorted by the vet again and again.
The fatality’s although far and few, will be more post-able than the many stories of things going fine, as wiebke said above.
Wishing you and charlie all the best x