Περίληψη:
Statement of the problem. Color matching between natural teeth, shade
guides, and metal-ceramic restorations is a common clinical problem.
Difficulties related to color matching arise from structural differences
that exist between metal-ceramic crowns and natural teeth, the limited
range of available ceramic shades, inadequate shade guides, different
types of metal alloys, and varying compositions of ceramic materials.
Purpose. The aim of this Study was to investigate the influence of
various metal alloys and 2 porcelains on the final color of
metal-ceramic complex.
Material and methods. Four commercial alloys for metal-ceramic
restorations, a Ni-Cr (Thermobond), a Co-Cr (Wirobond), a Pd-rich noble
(Cerapal-2), and a high noble Au-alloy (V-Delta) were combined with 2
porcelains (Vita Omega and Ceramco Silver) in metal-ceramic specimens
with a standardized thickness of layers. Five disc-shaped (10 x 1 mm)
specimens were prepared for each alloy/porcelain combination. Only
opaque and dentin layers were applied (shade A3). The specimens were
analyzed with a spectrophotometer, and data were obtained in the CIE Lab
color system. The recorded data were analyzed with a 2-way multiple
analysis of variance, a pair-wise comparison of group means (Student’s t
test), and finally, a categorical regression analysis of variance
(CATREG) (alpha = .01).
Results. The types of alloy substrate and overlying porcelain
significantly affected the color (P < .01). Au and Co-Cr alloys were
found to be brighter (higher L* values) than the Ni-Cr and the Pd
alloys (P < .01, SE 0.239). Cerainco porcelain was found to be most red
(higher a* values) of all tested alloys (P < .01). Gold and Pd alloys
caused a yellow shift to the metal-ceramic color compared to the Ni-Cr
and the Co-Cr alloys with both porcelains (P < .01, SE 0.165). The
detected color differences were visually perceptible for some
alloy-porcclain combinations.
Conclusions. The final color of metal ceramic specimens was influenced
both from the type of alloy substructure and from the type of overlying
porcelain.
Συγγραφείς:
Kourtis, SG
Tripodakis, AP
Doukoudakis, AA