10 years ago a porcelain crown & post was installed. It lasted a few years then the natural tooth broke. An implant with porcelain fused to metal crown was installed. 4 years later it developed a horizontal crack. A temporary patch for 1 year was done so my insurance would pay for new one 5 years after it was installed. 4 months after a new one it broke again. My dentist will pay but if it breaks again he will not. He is baffled. He checked my bite and implant. I wear an mouth guard regularly.