Evaluation of Fracture Resistance in Aqueous Environment of Four Restorative Systems for Posterior Applications. Part 1

• Published in: Journal of prosthodontics 2013-06, Vol.22 (4), p.256-260
• Main Authors: Dhima, Matilda, Assad, Daniel A., Volz, John E., An, Kai-Nan, Berglund, Lawrence J., Carr, Alan B., Salinas, Thomas J.
• Format: Article
• Language: English
• Subjects: Acrylic Resins - chemistry; Ceramic; Crowns; Dental Bonding; Dental Materials - chemistry; Dental Porcelain - chemistry; Dental Stress Analysis - instrumentation; Dental Veneers; Dentistry; fracture resistance; Light-Curing of Dental Adhesives; lithium disilicate; Materials Testing; Polymerization; posterior crown; press-on metal; Resin Cements - chemistry; Stress, Mechanical; Surface Properties; thin zirconia core; Water - chemistry; Zirconium - chemistry
• ISSN: 1059-941X; 1532-849X
• DOI: 10.1111/j.1532-849X.2012.00948.x

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.