Evaluation of fracture resistance in aqueous environment of four restorative systems for posterior applications. Part 1

Matilda Dhima, Daniel A. Assad, John E. Volz, Kai Nan An, Lawrence J. Berglund, Alan B. Carr, Thomas J. Salinas

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Purpose: The goals of this study were to: (1) establish a range of the performance of four restorative systems for posterior single-tooth crowns under single load to fracture submerged in an aqueous environment, (2) identify restorative system(s) of interest to be examined in the second study phase under sliding contact step-stress fatigue as full-contour anatomically appropriate single posterior tooth restoration(s), (3) establish a range for loading/testing for phase 2. Materials and Methods: Forty specimens (n = 10/group) of 2 mm uniform thickness were tested. Group 1: monolithic lithium disilicate IPS e.max Press; group 2: IPS e.max ZirPress, 0.8 mm zirconia core with 1.2 mm pressed veneering porcelain; group 3: IPS e.max ZirPress, 0.4 mm zirconia core with 1.6 mm pressed veneering porcelain; group 4: IPS InLine PoM. Specimens were bonded to a block of polycast acrylic resin on a 30° sloped surface with resin cement. Specimens were axially single loaded to failure while submerged under water. Results: There was a statistically significant difference (p < 0.001) in failure load among the four restorative systems. Lithium disilicate showed a mean failure load similar to mean maximum posterior bite forces (743.1 ± 114.3 N). IPS e.max Zirpress with a 0.4 mm zirconia core exhibited the lowest mean failure load (371.4 ± 123.0 N). Conclusion: Fracture resistance of monolithic lithium disilicate in an aqueous environment is promising and requires second phase testing to evaluate the potential of various thicknesses appropriate for posterior single tooth applications. Doubling the IPS e.max Zirpress zirconia core from 0.4 mm to 0.8 mm increased the fracture resistance of this restorative system threefold.

Original languageEnglish (US)
Pages (from-to)256-260
Number of pages5
JournalJournal of Prosthodontics
Issue number4
StatePublished - Jun 2013


  • Ceramic
  • Fracture resistance
  • Lithium disilicate
  • Posterior crown
  • Press-on metal
  • Thin zirconia core

ASJC Scopus subject areas

  • General Dentistry


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