Effect of molar preparation axial height on retention of adhesively-luted CAD-CAM ceramic crowns

Robert Wake, Richard Buckb, Nicholas DuVall, Howard Roberts

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Purpose: To evaluate the effect of axial wall height (AWH) on failure resistance of CAD-CAM adhesively-bonded, allceramic crowns on molar preparations with a conservative total occlusal convergence (TOC).Materials and Methods: 60 newly extracted maxillary third molars were divided into 5 groups (n = 12) and prepared for all-ceramic crowns with occlusal cervical AWH of 0, 1, 2, 3, and 4 mm, all containing a conservative 10-degree TOC. Scanned preparations were fitted with lithium-disilicate glass-ceramic crowns using a self-adhesive resin-composite luting agent after intaglio surface preparation with hydrofluoric acid and silane. Specimens were stored at 37°C/98% humidity for 24 h and tested to failure at a 45-degree angle applied to the palatal cusp on a universal testing machine. Mean results were analyzed using ANOVA and Tukey's test (p = 0.05). Results: Preparations containing 2, 3, and 4 mm AWH demonstrated similar and higher failure resistance than the 0- and 1-mm axial wall height groups. Conclusions: Under the conditions of this study, evidence is presented that under certain conditions CAD-CAM adhesive technology may compensate for less than optimal AWH. Based on both failure load results and failure mode analysis, adhesively-luted maxillary molar CAD-CAM crowns based on a preparation containing 10-degree TOC require at least 2 mm AWH for adequate resistance and retention. However, adoption of these findings is cautioned until both fatigue analysis and appropriate clinical evidence has been provided.

Original languageEnglish
Pages (from-to)545-550
Number of pages6
JournalJournal of Adhesive Dentistry
Issue number6
StatePublished - 2019

Bibliographical note

Funding Information:
This study was supported by 81 MDG Protocol FKE20140015N. Any opinions expressed in this work are of the authors only and do not represent the official opinion of the United States Air Force, Department of Defense, Uniformed Services Health University, or the United States Government.

Publisher Copyright:
© 2019, Quintessenz.


  • Adhesion
  • Axial wall height
  • Failure load
  • Lithium disilicate
  • Total occlusal convergence

ASJC Scopus subject areas

  • Orthodontics
  • Oral Surgery
  • Periodontics


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