Fractographic study of the behavior of different ceramic veneers on full coverage crowns in relation to supporting core materials.
OBJECTIVE
To observe porcelain veneer behavior of zirconia and metal-ceramic full coverage crowns when subjected to compression testing, comparing zirconia cores to metal cores.


METHODS
The porcelain fracture surfaces of 120 full coverage crowns (60 with a metal core and 60 with a zirconia core) subjected to static load (compression) testing were analyzed. Image analysis was performed using macroscopic processing with 8x and 12x enlargement. Five samples from each group were prepared and underwent scanning electron microscope (SEM) analysis in order to make a fractographic study of fracture propagation in the contact area and composition analysis in the most significant areas of the specimen.


RESULTS
Statistically significant differences in fracture type (cohesive or adhesive) were found between the metal-ceramic and zirconia groups: the incidence of adhesive fracture was seen to be greater in metal-ceramic groups (92%) and cohesive fracture was more frequent in zirconium oxide groups (72%). The fracture propagation pattern was on the periphery of the contact area in the full coverage crown restorations selected for fractographic study.


CONCLUSIONS
The greater frequency of cohesive fracture in restorations with zirconia cores indicates that their behavior is inadequate compared to metal-ceramic restorations and that further research is needed to improve their clinical performance. Key words:Zirconia, zirconium oxide, fractography, composition, porcelain veneers, fracture, cohesive, adhesive.
DDS, Occlusion and Prosthodontics, Department of Stomatology, University of Valencia, Valencia, Spain.
Ignacio
I
Farga-Niñoles
DDS, PhD, Associate professor, Occlusion and Prosthodontics, Department of Stomatology, University of Valencia, Valencia, Spain.
Rubén
R
Agustín-Panadero
DDS, PhD, Associate professor, Occlusion and Prosthodontics, Department of Stomatology, University of Valencia, Valencia, Spain.
Juan L
JL
Román-Rodriguez
MD, DDS, PhD, Adjunct Lecturer, Department of Stomatology, University of Valencia, Valencia, Spain.
María F
MF
Solá-Ruíz
DDS, PhD, Associate professor, Occlusion and Prosthodontics, Department of Stomatology, University of Valencia, Valencia, Spain.
María
M
Granell-Ruíz
MD, DDS, PhD, Professor of Occlusion and Prosthodontics, Department of Stomatology, University of Valencia, Valencia, Spain.
Antonio
A
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