What Can Be That Bluish Color on my Front Teeth Edges?

Without a picture it would be hard to tell you with 100% certainty but it sound like you are taking about the translucent enamel at the edge of the tooth.  If you have veneers or crowns, the ceramist may have added it, if it is within you natural tooth it is normal unless you find it getting worse which could indicate you are wearing your enamel down and now you are able to see through the layer.
 

I didn't see any pictures you might have sent, but it is very common for anterior teeth to have a "translucent enamel halo" at the edge. Some have it more than others, depending on the thickness & length of the enamel. In fact, a good ceramist will try to duplicate that look on porcelain veneers or crowns. It's a very natural look.

 

Hi A10 in NJ,

Without a picture or seeing you in person, it’s impossible to tell for sure, but most likely the bluish color you see is actually transparency in the enamel. 

Often this comes with wear or thinning of the enamel which is natural with age, or it sometimes appears with over bleaching. 

Unfortunately it is permanent, but it can be corrected with porcelain veneers.

Hope this helps.

Best,

Dr. Alper

 

The edges of your front teeth are composed of enamel which is a translucent material.  Enamel has optical properties that include luminescence, fluorescence and opalescence.  It is those light properties and the way the light gets absorbed and reflected from the surface of the tooth that gives the color characteristics to a tooth.  The bluish hue is a sign of healthy enamel, actually young enamel that has not been worn away and is intact.  So its is a sign of youth and is perfectly normal.  Dentists sometimes fight to try to recreate this in veneers and bonding.  If you don't like it, it can be corrected with applying an opaque color composite over it, but this may require the removal of some healthy enamel.