This investigation compared, by quantitative analysis, the surface roughness of dental porcelain submitted to three different treatments (glaze, trimming and polishing), utilizing a surface profiling instrument. The parameters Ra (median roughness), Rz (median of the maximum profile heights of five sample lengths), Rpm (median of the maximum profile heights related to the median line of five sample lengths), Pc (peak count per centimeter) and Rpm/Rz (proportional parameter) were evaluated. In addition, the correlation between Ra and the other parameters was analyzed. Based on the results obtained, it was seen that the Ra parameter did not present any correlation with the other parameters in some of the situations evaluated. This demonstrates that complementation of the measurement with other parameters is always necessary, providing a better evaluation of the functional properties of a surface.