Crowns Are too Small on Front Teeth, What Can I Do?

So sorry to hear about your unsatisfactory crown and bridge work.  As stated by other doctors, the only ideal corrective solution involves remaking them.  Having said this, a thorough review of possible corrections needs to be done.  As suggested, creating models of your teeth in plaster and mounting them on an articulator that simulates your bite and jaw movements is a must to see what can be done.  Sometime repositioning teeth with crowns can be done and combined with gingival trimming extra length can be achieved.  Also sometimes Orthodontic movement can help with room creation including sometimes Invisalign clear braces.  Another option mentioned is to add length to posterior teeth to open the bite in the anterior and create extra room for increased length if desired.  Talk to a well referenced and respected cosmetic dentist and he can help you evaluate your options. 

Sorry to hear that you are unhappy with your smile. Unfortunately the only solution would be to have the work redone.  I do not have any photos to look at so I am not sure why the teeth are so small, it may be related to the amount of space that was available or possibly your bite.  I would consult with a dentist near you to find out your options.