I remember back in the old days, the dentist used a "rubber dam" to prevent stuff from getting into the throat. Worked very well. But there are better things now.
You might have difficulty finding a dental office who will take a patient whose swallowing is compromised. However, there are people who do it. Dentists have developed procedures for dealing with paralyzed and stroke patients.
Applesos, with all due respect, why worry about teeth cleaning? The most important thing, in my very humble opinion and limited experience, is to clean out your PALS mouth to prevent trash from building up. Old food, bits of medications, and strange stuff can gather in the mouth of a person who can't use their tongue to sweep the mouth normally. Let us know how it goes.