J Adv Prosthodont.  2018 Aug;10(4):300-307. 10.4047/jap.2018.10.4.300.

In vitro performance and fracture resistance of novel CAD/CAM ceramic molar crowns loaded on implants and human teeth

Affiliations
  • 1Department of Prosthetic Dentistry, UKR University Hospital Regensburg, Regensburg, Germany. verena.preis@ukr.de

Abstract

PURPOSE
To investigate the fatigue and fracture resistance of computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic molar crowns on dental implants and human teeth.
MATERIALS AND METHODS
Molar crowns (n=48; n=8/group) were fabricated of a lithium-disilicate-strengthened lithium aluminosilicate glass ceramic (N). Surfaces were polished (P) or glazed (G). Crowns were tested on human teeth (T) and implant-abutment analogues (I) simulating a chairside (C, crown bonded to abutment) or labside (L, screw channel) procedure for implant groups. Polished/glazed lithium disilicate (E) crowns (n=16) served as reference. Combined thermal cycling and mechanical loading (TC: 3000×5℃/3000×55℃; ML: 1.2×106 cycles, 50 N) with antagonistic human molars (groups T) and steatite spheres (groups I) was performed under a chewing simulator. TCML crowns were then analyzed for failures (optical microscopy, SEM) and fracture force was determined. Data were statistically analyzed (Kolmogorow-Smirnov, one-way-ANOVA, post-hoc Bonferroni, α=.05).
RESULTS
All crowns survived TCML and showed small traces of wear. In human teeth groups, fracture forces of N crowns varied between 1214±293 N (NPT) and 1324±498 N (NGT), differing significantly (P≤.003) from the polished reference EPT (2044±302 N). Fracture forces in implant groups varied between 934±154 N (NGI_L) and 1782±153 N (NPI_C), providing higher values for the respective chairside crowns. Differences between polishing and glazing were not significant (P≥.066) between crowns of identical materials and abutment support.
CONCLUSION
Fracture resistance was influenced by the ceramic material, and partly by the tooth or implant situation and the clinical procedure (chairside/labside). Type of surface finish (polishing/glazing) had no significant influence. Clinical survival of the new glass ceramic may be comparable to lithium disilicate.

Keyword

Glass ceramic; Dental crown; Dental implant; Fatigue; Fracture resistance

MeSH Terms

Ceramics*
Computer-Aided Design
Crowns*
Dental Implants
Fatigue
Glass
Humans*
In Vitro Techniques*
Lithium
Mastication
Microscopy
Molar*
Tooth*
Dental Implants
Lithium
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