There is no "teeth factor." They're not factors, just protective structures that can preserve DNA longer than bones or muscles or blood.
The further removed in biological relatedness, the more dissimilar DNA becomes from ours. Look at the cladogram in post #83, Follow the succession line back in time (down). The DNA from species at each junction becomes less and less similar to ours.
DNA is a footprint leading back in time, but there are other dating methods; tested methods, that give consilient dates for artifacts too old for DNA or soft tissue to remain.
"...more to it than sheer evolution?" That's a statement of personal incredulity, not an evidence-derived conclusion.
What other factors are you hinting at? God?
God isn't a mechanism. It doesn't address 'how?'. God is an agent, and I'd suggest an unneeded, superfluous one, given the known, natural mechanisms driving evolution.