Does bleaching have any effect on existing dental work, such as fillings, veneers or crowns?

Tooth-coloured composite (plastic resins) or ceramic (porcelain) tooth restorations can't be lightened with bleach. They remain the same colour. Therefore, you will have to consider what your smile will look like if your natural teeth get lighter but your restorations do not. This is a good topic to discuss with your dentist at Smile Centre, who can run through the options in your particular case.