Just as you may have problem with your natural teeth, bridges and teeth with single crowns are subject to problems. These problems include recurrent decay, recession and exposure of crown margins, fracture or porcelain, periodontal disease and fracture of the teeth, to name a few. Remember your teeth are still under the crowns, and therefore problems can develop in addition to actual problems with the crowns themselves.
Regular check-ups and evaluations can go a long way to maintain extensive dental "work", and excellent home care is also essential in maintaining crowns and bridges for as long as possible.
Just as your car requires regular maintenance, your teeth, gums and restorations require regular continuing care to maintain optimum health.