Eeek. My Sis lives in Ohio also and is an attorney. I knew kickbacks were illegal here but she says they are also illegal in Ohio.. Kickbacks are Worse when insurance fraud is involved. If you suspect this you might consider different doctors. Did the dentist recommend that particular orthodontist?
But anywho...my DD started by an oral surgeon removing some baby teeth and some God given extra teeth, I had them too as a kid, gene pool thing. The Oral Surgeon was covered her Dads Health Insurance and cost little. The co-pay with Dental Insurance would have cost more to have the same teeth removed and the cap yearly for dental. You might want to check the prices out of pocket between Dental Insurance and Medical Insurance.
My DD started the Ortho when she was 8 years old. She has a slender face and a bottom jaw that that was not forward enough for teeth to mesh correctly top to bottom. She wore an appliance that was attached to her back teeth that exercised her jaw forward as she ate and spoke. It corrected what is referred to mostly in men as a weak chin.
After that she went onto braces in Middle School. Many orthodontists in her era of 2000 were into a 2 phase braces. On in elementary school. Off a few years and back on again after growth. Her Ortho didn't believe in moving teeth twice, he believed it weakened the roots too much.
For us the invoicing started when her appliance was attached. They worked with Dental Insurance, It depended basically on how the plan paid, monthly, yearly or flat allowance per person on policy. Her Dads company has very good health insurance 100% paid by the firm and the Dental Plan was equally as good for orthodontist. At best it was below the Maximum top out. If T's Dentist is going to take a bit of time you might want to evaluate the best dental plan for T's needs for 2021, gamble if Pre-existing conditions are allowed to be excluded by possible new rulings. Possibly a more expensive plan might be the better plan that actually covers more of what he will require. Health Insurance these days is like a darn chess game when picking plans.

And some firms offer better dental and than others. *bangs head*
Hope that helps.