I sleep with a pacifier sometimes. It rarely has any impact on my dreams. On a few occasions I've had dreams about chewing but it's generally neutral to my sleep. I don't believe dreams mean anything other than what we've been thinking about or how sensory information gets processed while sleeping, so I can't suggest anything more helpful than having something keeping you from fully biting down makes you think of tooth loss somehow.
The teeth falling out dream is actually a pretty common phenomenon. It's generally associtated with anxiety and depression. What's probably at work is that you use your paci more when you're anxious or depressed, and it just happens to correlate with the dream being more frequent as well.
Both my wife and I have those dreams, and they're really disturbing. We both have poor teeth resulting in many trips to the dentist and lots of fillings. I think they're anxiety dreams caused by having dental problems.