How can one tell whether inhale causality or exhale causality?

I have seen 2 sleep neurologists. One is adamant that bipap will achieve nothing in terms of reducing aerophagia, and the other is diametrically opposed.

Does anyone have experience using nasal (or other) CPAP and a dental appliance (mandibular positioner) at the same time, in order to get better results ? I have seen a dentist who told me that this was a possible using the TAP appliance. He said that the manufacturer of the TAP also made an optional...