Dental veneers can be used by dentist to either improve the appearance of a tooth or to restore it if it is damaged.  Here are some dental problems where a dental veneers are useful.

1) To improve the appearance of darken teeth where previous teeth whitening treatments failed.
2) To restore teeth that are moderately worn out. (Note: severely worn teeth should be repaired with a dental crown)
3) To restore fractured teeth
4) To close spaces between teeth
5) To arrange the appearance of slightly misaligned teeth

For both 4 and 5 it is recommended to consider orthodontics services first.   However talk to your dentist and discuss the correct coarse of dental care treatment for you.