I researched a bit on phytic acid, considering this diagram of how it binds to nutrients



I came up with this table (left out the protein)

phytic acid  660.04   100
calcium       40.078   6
magnesium  24.305   3.6
zinc           65.409   9.9
iron            55.845   8.5

First column are molar weights, the second is normalized to 100 for phytic acid. So 100mg phytic acid theoretically would bind to 6mg Ca, 3.6mg Mg, etc. (if my calculations here are correct, I don't have much clue about chemistry actually).

According to this phytic acid is a lot worse regarding zinc/iron availability than calcium/magnesium, which goes along with what's written on Wikipedia:

it chelates and thus makes unabsorbable certain important minor minerals such as zinc and iron, and to a lesser extent, also macro minerals such as calcium and magnesium.

Even if you consume like 5000mg phytic acid daily it won't affect dietary Ca/Mg that much (considering their high RDAs), plus in practice the binding numbers will be probably lower. So I'm wondering, why does it have such a bad reputation regarding teeth health? Are zinc and iron that important for the teeth? Is it possible that it binds calcium/magnesium directly from the teeth already in the mouth? Can't think of other options.