Veneers can be placed on worn teeth and are typically used to correct problems related to the shape and color of the teeth. These problems include worn teeth, which are worn away by exposure to acids, bacteria, weather, and aging.

Placing veneers on worn teeth can improve the appearance of teeth and restore their natural shape and color. Veneers can be used to correct problems such as:

1. Loss of natural dentin: Excessive wear on teeth can lead to loss of natural dentin, and veneers can be used to cover these defects and improve the appearance of teeth.

2. Decayed teeth: Severe decay can lead to tooth erosion and loss of parts of them, and veneers can be used to repair decayed teeth and improve their appearance.

3. Other deformities: Excessive wear on teeth can cause other deformities such as crookedness, curves, and cracks, and veneers can be used to correct these problems and improve the appearance of teeth.

However, a dentist should be consulted to determine whether it is appropriate to place cosmetic veneers on decayed teeth according to the patient's condition and desired cosmetic goals. This may require other procedures before placing the veneers, such as treating decay or cleaning the teeth.