Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns.
As per your complain Flouridex toothpaste contains main ingredients as Potassium Nitrate and Sodium
Fluoride and is an effective anti cavity dentifrice/ toothpaste..
Although such kind of side effects are not commonly observed after using it and blackening between teeth can be due to staining of teeth that is a normal process if brusing is not proper while some individuals are more prone to develop staining due to rough teeth,..
Chipping of teeth is due to attretion and abrasion..
I would suggest you to consult an Oral physician and get evaluated and a thorough clinical evaluation can be diagnostic..
Scaling can be done to remove stains along with demonstration of proper brushing technique..
For chipping of teeth the exact cause like teeth grinding habit or other causes like physiologic abrasion can be checked for and treated accordingly..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.