Zirconia veneer is a type of veneer that is preferred for its aesthetical look, luminous transmittance that is very close to natural teeth, and thereby the color match and natural appearance, which are successfully achieved.  
Zirconia is a tooth-colored material found in the structure of porcelain and used instead of metal. Since it does not cause the gray reflection caused by metal, it gives veneered teeth a more aesthetical and natural look. The color change in the gingiva where the veneer and the gingiva meet is less common in zirconia veneers. Allergic reactions to the materials found in metal, which some people may have, are not experienced with zirconia veneers.   
The major cause of bad breath is tooth and gingiva problems. Old veneers, dental caries, and gingival diseases are among the problems that result in bad breath. It is treatable.