Statement of problem
The opacity of the metal framework in metal ceramic restorations results in reduced
light transmission through the tooth that diminishes the esthetics of the tooth.
Purpose
The purpose of this study was to investigate the color change that occurs apically
to a metal ceramic restoration as a result of altering the metal framework design.
Material and methods
Color change relative to the unprepared tooth (ΔE) between various metal ceramic restorations
was determined using computer imaging and CIELAB coordinates and compared to previously
determined levels of clinical acceptability. Color change was evaluated by examining
2 conditions (the metal copings and the completed metal ceramic restorations), 4 framework
designs (metal collar and porcelain margins with 0-mm, 1-mm, or 2-mm cutbacks), and
2 locations on the tooth apical to the margin of the restoration, using an imaging
system developed at the Minnesota Dental Research Center for Biomaterials and Biomechanics.
The data were analyzed statistically using repeated measures analysis of variance
(P=.05).
Results
For metal ceramic restorations there exists a significant (P=.001) color change (ΔE) between all framework designs except for the 0-mm and 1-mm
cutbacks. Color change (ΔE) in the location above the cemento-enamel junction was
significantly greater (P=.004) than below the cemento-enamel junction.
Conclusions
The framework design for metal ceramic restorations can affect the esthetics of the
adjacent natural tooth. A minimum 2-mm facial cutback of the metal framework is necessary
for there to be a significant difference in color change. (J Prosthet Dent 2008;99:468-476)
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Article info
Footnotes
Supported by the Tylman Grant from The American Academy of Fixed Prosthodontics; awarded first place in the 2004 Tylman Research Award Competition.
Presented at the 53rd Annual Meeting of the American Academy of Fixed Prosthodontics, February 2004, Chicago, Ill.
Identification
Copyright
© 2008 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.
