How does a dentist decide between dental crowns or veneers?

judging from the picture, it seems to me that you have short looking teeth because the width and the height of the teeth appear to look the same. Normal looking teeth have a width that is less than the height. Usually this ratio is anywhere from 70% to 80%. A tooth can look short due to: a) excessive gums or b) the wear and shortening of the edge of the tooth. We need to establish the cause of the short or small teeth before proceeding. If it's due to excessive gums, then we can perform a laser gum recontouring. We can also consider lengthening the teeth simultaneously with porcelain veneers.

In order to adhere the composite material to your teeth, the enamel surface has to be cleaned and treated with an acid gel (35% hydrophosphoric acid). The acid treated surface (etched) is impregnated with a bonding resin that has to be set using a special curing light. Only after these 2 steps can the composite be applied to the tooth surface and sculpted. The composite also must be set using the same curing light. If NO tooth preparation (shaving) is done beforehand, the final veneers can be quite bulky. This may not be a desirable look for some people.