Effect of Endodontic Access Preparation on the Retention of Zirconia Crowns with Temporary or Permanent Access Hole Restorations: An In Vitro Study

Abstract

Objectives: To evaluate the effect endodontic access preparation had on the retention of anterior zirconia crowns after restoring the access hole with temporary versus permanent restorative materials. Methods: 30 anterior zirconia crowns were milled from 5Y-TZP zirconia and bonded to a 3D printed die with resin cement. Crowns were randomly divided into three groups including negative control (NC, n = 10) with no endodontic access preparation; positive control (PC, N = 10) received endodontic access preparation and was restored with a temporary restorative material (Cavit); composite restoration (CR, N = 10) received an endodontic access preparation and then the access hole was restored with composite resin. Results: Considering the retention of crowns in NC group, PC group lost approximately 50% of its retention while the CR group had approximately 150% increase in the retention. The difference between the three groups was statistically significant (P \u3c 0.05). Conclusion: Restoring the endodontic access hole of a central incisor zirconia crown with composite resin improves the retention of the crown