If the absence of teeth is a dominant trait, then why is it not seen in generations? My teacher taught that absence of teeth is a mendelian dominant trait, but why don't we see this trait if it is dominant?
Hypodontia isn't a single gene phenotype, but a poli-genic mechanism involved with epistatic phenomenons and environmental scenarios.
The trasmission isn't clear till now, but when you're talking about a poli-gene phenotype isn't so easy to describe the way in which the trasmission is performed. You could find every info about this disease here, in a meta-review study: