Topical Applications for Tooth Strengthening

Recently, I've been seeing lots of advertisements having to do with tooth strengthening by using various mouthwashes, and in one case even chewing gum.  I'm wondering if this mode of intervention works, or if the only way to get strong teeth is through what you take internally.  
I was diagnosed with Osteoporosis awhile back, and assume that this can also affect the density of my teeth...........is that correct?  I would appreciate any suggestions you might have in regard to what I can do personally to strengthen my teeth.  Lately, they feel like they have the consistency of Faberge Eggs or something similar......
Thanks in advance for all responses......

[Jerome Tsang, DDS]

Strengthening teeth is a broad concept.  If you're discussing specifically to preventing cavities, then chewing xylitol gum or using fluoride mouth rinses and such can help prevent cavities through different methods.  

Osteoporosis probably won't affect the density of your teeth too much but may affect your jawbone.  The outer enamel layer of a tooth doesn't repair itself as there isn't any live cells to produce more enamel.  So any problem with osteoporosis shouldn't affect the outer enamel layer.