Efects of batch variation on shade of dental porcelain

Three different batches of three commercially available porcelains were applied to 36 specimens of two noble alloys. The shades were visually compared by nine observers. Results indicated the following.1.No color differences were found among specimens of individual batches.2.Discerning color changes were observed among three batches of one brand of porcelain.3.The porcelain fired in the laboratory may not match the manufacturer's standard shade guide.4.Batch to batch variation of porcelain may necessitate the fabrication of customized shade tabs with fresh batches of porcelain.