There are certainly more associated dentitions. The challenge is getting them donated to museums and then the time consuming process of scanning each tooth. Most (if not all) Megalodon jaw displays are what we’d call a composite dentition. The artist/exhibitor will take a bunch of beach float teeth and compose a jaw. I don’t think anyone would put a real associated dentition into a plaster jaw as an exhibit, simply because it would be less accessible for research.
It would be great if we could scan more dentitions and I think we’re on that path, but it will take a long time.