I highly recommend a pediatric dentist, we drive 20 mi. and it is worth it!
Although my kids were cooperative about opening their mouth for him, the staff was great about any sensory issues. We've dealt with lots of gag reflexes, taste and smell issues. We use "happy air" (gas) and have even had tranquilizers prescribed for tooth removal.
Even if the first visit only results in sitting in the chair it would at least be familiar for next time.
But I feel for you. This is tough for them and for you! I wish you well
_________________
I love you as you are, as you seek to find your own special way to relate to the world