Mathematical advances allowing bone histomorphometric quantification from flat surfaces (conversion of surface to volume), have provided us with objective units of measurement. Stereology is a mathematical discipline that may be defined as the science of deducing three-dimensional structures from two-dimensional samples. Conversion from area to volume is deduced from Delesse´s theorem (1848): fractions of area are equal to fractions of volume in infinitely thin sections. 2-D histologic sections show 3-D profiles. Currently, computer programs automatically or semi-automatically quantify the components of bone tissue. There are histomorphometric parameters obtained by expert panel concensus for the quantitative measurement of bone.