Placing crowns to prevent tooth fracture is thought to be a common but infrequently documented treatment procedure. Two studies are described that provide information about dentists' use of crowns to prevent tooth fracture. North Carolina general dentists indicated that 44% of the crowns they placed were for the principal reason of fracture prevention. However, when groups of dentists examined the same patients, there was little agreement about which teeth should be crowned due to risk of fracture. These results suggest that the placing of crowns to prevent fracture merits a careful determination of effectiveness and appropriateness.