Optimum thickness of opaque and body porcelain

Nine hundred specimens of six shades of two commercially available dental porcelains were made with different thicknesses of opaque and body porcelain. The color of specimens were compared with shade guide samples by seven observers. The results were as follows: 1. The thickness of opaque and body porcelain to produce optimum color varies from shade and in different porcelain systems. 2. Complete visual mask out of the alloy by the opaque may not produce the desired shade. 3. Excessive opaque will not effect the shade of porcelain noticeably, whereas excessive body porcelain influences the shade of porcelain. 4. Manufacturers' recommendations for each shade should include the optimum required thickness of both opaque and body porcelain.