An energy dispersive x-ray microanalysis study was performed
throughout the total length of cementum on five impacted human teeth.
Mineral content of calcium, phosphorous, and magnesium were determined
with an electron probe from the cemento-enamel junction to the root apex
on the external surface of the cementum. The concentration profiles for
calcium, phosphorous, and magnesium were compared by using Ca/P and
Mg/Ca atomic percent ratio. Our findings demonstrated that the
Ca/P ratio at the cemento-enamel junction showed the highest values
(1.8–2.2). However, the area corresponding to the acellular
extrinsic fiber cementum (AEFC) usually located on the coronal one-third
of the root surface showed a Ca/P media value of 1.65. Nevertheless,
on the area representing the fulcrum of the root there is an abrupt change
in the Ca/P ratio, which decreases to 1.3. Our results revealed that
Mg2+ distribution throughout the length of human cementum
reached its maximum Mg/Ca ratio value of 1.3–1.4 at.% around the
fulcrum of the root and an average value of 0.03%. A remarkable finding
was that the Mg/Ca ratio pattern distribution showed that in the
region where the Ca/P ratio showed a decreasing tendency, the
Mg/Ca ratio reached its maximum value, showing a negative correlation.
In conclusion, this study has established that clear compositional
differences exist between AEFC and cellular mixed stratified cementum
varieties and adds new knowledge about Mg2+ distribution and
suggests its provocative role regulating human cementum metabolism.