Preparing a tooth for a crown removes tooth structure and cannot be reversed. The nerve sometimes reacts to being prepared and can die months or years later, meaning the tooth needs root canal treatment through the crown. Crowns can chip, and they can come loose and need recementing. Decay can start at the margin where the crown meets the tooth, particularly if cleaning there slips. Gum can recede over time and expose the edge, which shows more on front teeth than back ones.A crown does not make a cracked tooth certain to survive — it improves the odds, and how far a crack already extends can't always be seen before treatment. Grinding shortens the life of any crown. Nobody can promise how long an individual crown will last.
Any surgical or invasive procedure carries risks. Before proceeding, seek a second opinion from an appropriately qualified health practitioner. Individual results vary.