Well, after 2 weeks on IP6 I can reassure everyone that that teeth sensitivity was just a temporary thing. I have had it for only 2 days after I started taking IP6 and it wasn't that bad after all.
Over the past 2 weeks I even tried increasing the dosage up to 4gr (3gr + 1gr) of IP6 + 1300mg (2x650mg) a day and didn't have any problems with my teeth.
I'm still taking it early in the morning but just 2gr.
Will let you know if anything changes.