Objective: The objective selection of the correct shade of a resin composite restorative material is a challenge in esthetic dentistry. Aim of this study was to correlate the effect of the overlay of a translucent shade on the color of a selected shade. Methods: The material selected for the trial was Z250 (3M/Espe). For this product, the following 5 Vita shade were tested: A2, A3, A3.5, B2, B3. Sample disks of 15 mm in diameter were made in these shade as well as in T shade at a thickness of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 mm. The overlaying were measured by progressively reducing the thickness of the base color while increasing the thickness of the translucent material so to maintain the total thickness at 5.0 mm. The various combinations were measured in the CIE L*a*b* system against an 50% gray background with a spectrophotometer (Ocean Optics, Fl, USA) equipped with an integrating sphere. The color comparison between the 5.0 mm base shade and the various layering combinations were calculated using the formula DeltaE=[(L₁-L₂)²+(a₁-a₂)²+(b₁-b₂)²]^1/2  (Clarke, 1983). Results: Calculated DeltaE values are shown in the Table. The results have to be regarded with the consideration that DeltaE=3.3 is the limit for the eye in appreciating a difference in color. Following this indication, this study showed that by overlaying a Translucent shade onto a selected base shade, the original color changes over an eye-appreciable level. Conclusions: This data has to be taken into consideration in clinical multi-layer technique for direct restorations.

 

Shift from base color (A3+T)
A3 = 5.0 mm					T = 2.5mm					T = 5.0 mm
					A3 = 2.5 mm
DeltaE	4.0	4.5	7.7	9.9	8.3	8.2	9.1	7.6	7.7	6.9

Back to the Dental Materials: VIII - Others-Non-metallic Program
Back to the 81st General Session of the International Association for Dental Research (June 25-28, 2003)

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