Can zirconia crowns stand up to chewing? a 24-Month test aims to find out

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * At least 18 years of age (selected regardless of sex, race or other ethnic characterization) * Vital or endodontically treated tooth * Antagonist present * Classify as ASA I or ASA II according to the American Society of Anesthesiologists (ASA) * In need of an indirect full-coverage restoration (crown) on at least one posterior tooth (premolar or molar) * Fulfilling all medical and dental requirements for preparation of a full-coverage crown * Angle Class I occlusal relationship with a minimum of 20 remaining teeth * Adequate intra-arch space allowing for satisfactory restoration of the abutment teeth. If opposing teeth have supra-erupted, an ideal occlusal plane will be restored by enameloplasty. In cases of severe supra-eruption, patients will need to consent to alternative means of restoring an ideal plane of occlusion. This may involve surgical crown lengthening and/or restoration of the tooth. Otherwise, they will be excluded from the study. * Dentition free of active periodontal disease (probing depth and attachment levels at within normal limits, no furcation involvement, no mobility). Individuals meeting other criteria but presenting with active periodontal disease will be referred to the Post-Graduate Periodontal Clinic for treatment and subsequently re-screened. * Willingness and ability to comply with the pre- and post-operative diagnostic and clinical evaluations required for the study. * Willingness and ability (including financial) to comply with the final restorative treatment plan that will be accomplished upon completion of participation in the study. * Willingness and ability to understand and comply with Institutional Review Board (IRB)/Ethics Committee requirements as outlined in consent forms, which have to be signed by the patients. * Subjects are responsible for payment of regular dental procedures. Exclusion Criteria: * Severe wear facets and/or parafunctional activities such as clenching or nocturnal bruxism * Pulpitis, no hypersensitivity on biting and temperature (visual analog scale \<3) * Insufficient endodontic treatment * Periapical pathology * Pregnancy during the treatment phase * Significant medical conditions or drug use that could interfere with evaluation (i.e., narcotics, NSAIDs) * Medical conditions that preclude the subject from carrying out oral hygiene regimens (i.e., severe arthritis affecting the hands) * Social history that indicates a risk of poor compliance (i.e., history of alcohol or drug abuse) with proper maintenance of restoration