Contraindications of porcelain veneers

Dental veneers are not recommended in the following cases

When an important part of the tooth has to be polished off, which would expose a significant quantity of dentin (the layer under the enamel).
When the teeth are significantly oriented forward, the application of veneers will make this position worse and push the lips forward. An orthodontic treatment is recommended beforehand, in order to correct the position of the teeth.
When the teeth have large obturations or the nerve removed and there is significant loss from the structure of the tooth. The quantity of enamel used to attach the veneer is insufficient to ensure long term resistance. A dental crown is recommended instead.
When there are untreated gum diseases or cavities.
When the oral hygiene is deficient, cavities may appear on the edge of the veneer and the gum may become diseased.
In patients with vicious habits, such as chewing bones, teeth friction or grinding. The forces which appear in these activities are strong and may chip or fracture the veneer, just as they do with natural teeth. These patients may receive veneers if they are committed to wearing a mouthguard every night, and give up their chewing habits.