For anterior NuSmile Signature crowns, it is highly recommended to replace the crown if a portion of the esthetic coating is displaced or lost rather than attempting to repair the defect. There are a couple of repair techniques that provide adequate results intraorally, but, all are time consuming and tedious. It is probably reasonable to cut a window to repair an occlusal chip or wear area on a posterior crown if you wish. NuSmile will replace at no charge the occasional chipped crown if you will return it to NuSmile after replacement. Before returning a NuSmile crown for replacement please contact NuSmile Customer Service.