The considerations to dental veneers include:

1. The process is not reversible
2. Veneers are more costly than composite resin bonding
3. Veneers are may need to be repaired or replaced should they chip or crack
4. Tooth may become more sensitive to hot and cold foods and beverages because enamel has been removed
5. Veneer color cannot be altered once in place and should be properly specified during consultation with your dentist. If you plan on whitening your teeth, whitening should be done before getting veneers.
6. Veneers can dislodge and fall off, although not common. To minimize the chance of this occurring, do not bite hard objects or otherwise put pressure on your teeth.
7. Veneers are not a good choice for individuals with unhealthy teeth (for example, those with decay or active periodontal disease), weakened teeth (as a result of decay, fracture, large dental fillings) or for those who have an inadequate amount of existing enamel on the tooth surface.
8. Individuals who clench and grind their teeth are poor candidates for porcelain veneers, as these activities can cause the veneers to crack or chip.

How Long Do Dental Veneers Last?

The life span of a veneer depends on the amount of "wear and tear" the veneer is exposed to, how well you follow good oral hygiene practices, and your personal mouth-related habits. Veneers generally last between 5 and 10 years or more.

Do Dental Veneers Require Special Care?

No. Continue to follow good oral hygiene practices including brushing and flossing as you normally would. Even though porcelain veneers resist stains, your dentist may recommend that you avoid stain-causing foods and beverages (for example, coffee, tea or red wine).

Source from http://www.webmd.com