title: Survival of ceramic computer-aided design/manufacturing crowns bonded to preparations with reduced macroretention geometry.
abstract: OBJECTIVE
  Adhesive cementation reduces the need for macroretentive preparation for crowns. This study investigated the survival and clinical rating of monolithic computer-aided design/manufacturing (CAD/CAM) ceramic crowns bonded to preparations with reduced macroretention, hypothesizing that adhesion would compensate for reduced retention geometry.
  
  
  METHODS
  Two-hundred eight posterior CAD/CAM-generated crowns from feldspar block ceramic were adhesively bonded in 136 patients in three preparation groups: classic (100% stump height, n = 70); reduced (reduced stump height or irregular stump, n = 52); and endo (absent stump but pulp chamber retention cavity, n = 86). Crowns were examined at baseline and after 55 +/- 15 months using modified USPHS criteria. Plaque and bleeding of gingiva around the crowns were assessed.
  
  
  RESULTS
  Cumulative Kaplan-Meier survival of crowns on premolars/molars was: classic = 97.0%/94.6%; reduced = 92.9%/92.1%; and endo = 68.8%/87.1%, confirming the hypothesis for classic, reduced, and endo molars as well as for classic and reduced premolars. A significant difference was found between classic and endo premolar crowns, rejecting the hypothesis for endo preparation on premolars. Plaque and bleeding indices were significantly lower for crowned teeth than for controls.
  
  
  CONCLUSIONS
  The survival of classic and reduced crowns was rated adequate for premolars and molars. Endo preparation appeared acceptable for molar crowns but inadequate for premolar crowns.
authors.affiliation: Clinic of the Division of Aesthetic and Computer Restorations, Department of Preventive Dentistry, Periodontology and Cariology, Center for Dental and Oral Medicine, University of Zurich, Switzerland. andreas.bindl@zzmk.unizh.ch
authors.forename: Andreas
authors.initials: A
authors.lastname: Bindl
authors.forename: Björn
authors.initials: B
authors.lastname: Richter
authors.forename: Werner H
authors.initials: WH
authors.lastname: Mörmann
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D001641:Bicuspid; D002484:Cementation; D002516:Ceramics / Q000737:chemistry*; D017076:Computer-Aided Design; D003442:Crowns; D001840:Dental Bonding; D003774:Dental Plaque Index; D003776:Dental Porcelain / Q000737:chemistry; D017268:Dental Prosthesis Retention; D019232:Dental Restoration Failure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005500:Follow-Up Studies; D005884:Gingival Hemorrhage / Q000145:classification; D006801:Humans; D008422:Materials Testing; D008963:Molar; D010512:Periodontal Index; D011176:Post and Core Technique; D017680:Potassium Compounds / Q000737:chemistry; D011446:Prospective Studies; D016019:Survival Analysis; D019231:Tooth Preparation, Prosthodontic / Q000379:methods*
chemical_list: D000538:Aluminum Silicates; D017220:Dentin-Bonding Agents; D017680:Potassium Compounds; D003776:Dental Porcelain; C016447:feldspar