Axial Wall Height Effect on Adhesively Luted Ceramic Crown Failure on Preparations Containing Advanced Total Occlusal Convergence
Abstract
Objective : To analyze the axial wall height (AWH) significance in adhesively-luted CAD/CAM crowns on preparations containing a 20 degree total occlusal convergence (TOC). Methods : 60 recently-extracted maxillary third molars were randomly divided into 5 groups (n=12) and prepared for CAD/CAM ceramic crowns with a 20-degree TOC with AWH of 0,1,2,3, and 4mm. Scanned preparations (CEREC) were restored with full-coverage lithium desilicated restorations and luted with a self-adhesive resin luting agent after hydrofluoric acid etching and silanation . All manufacturer recommendations were followed. Stored specimens (37C/98 % humidity) were tested to failure (0.Smm/min) after 24hrs on a universal testing machine with load applied to the palatal cusp at 45 degrees to the root long axis. Failure load was converted to MPa using the bonding surface area with the mean data analyzed using Kruskal-Wallis/Dunn's (p=0.05). Failure mode was analyzed for all specimens. Results: Preparations containing two, three and four millimeters of AWH demonstrated a greater failure load resistance to dislodgement when compared to zero and one millimeter AWH groups, which was similar to calculated failure stress results. Conclusions:Under the conditions of this study, maxillary molar preparations with a 20 deg OC convergence restored with adhesively-luted lithium disilicate CAD/CAM full coverage restorations require at least 2mm of AWH for adequate resistance to dislodgment. This study provides some evidencethat adhesion technology may compensate less than optimal preparation features.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 07, 2017
- Accession Number
- AD1128372
Entities
People
- Robert M. Spriggel
Organizations
- Uniformed Services University of the Health Sciences