> Talk to somebody you trust with a degree in the field.

Tough ask for a lot of people! I have a distant uncle who works as a dentist in the Appalacians and does a lot of pro-bono work. My family has a tradition of taking the children on a trip to see him to ask if they really need braces. Often the answer is no.

I’d feel confident asking him this question, but I don’t think most people have someone like that.

I'm interested in mewing for the purported facial aesthetic and breathing benefits

Orthodontists are incentivized against embracing orthotropics by their current knowledge and business model. They prefer interventions they can charge for (braces, slenderizing) over practices which can be adopted without intervention. This may be why the field emerged from dentists rather than orthodontists.

“It is difficult to get a man to understand something, when his salary depends upon his not understanding it” — Upton Sinclair

> This may be why the field emerged from dentists rather than orthodontists.

Orthodontists are dentists.

I'm referring to dentists who do not practice orthodontistry, and therefore do not have careers hinging on the status quo.

but dentists aren't always orthodontists. I think OP meant those that aren't.

Yes and they call themselves functional orthodontists

http://www.aafo.org/