title: X-ray microanalysis of human cementum.
abstract: 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 Mg(2+) 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 Mg(2+) distribution and suggests its provocative role regulating human cementum metabolism.
authors.affiliation: Laboratorio de Biología Celular y Molecular, Facultad de Odontología, UNAM, Cd. Universitaria, Coyoacán, México D.F. 04510, México.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Alvarez-Pérez
authors.forename: Octavio
authors.initials: O
authors.lastname: Alvarez-Fregoso
authors.forename: Jaime
authors.initials: J
authors.lastname: Ortiz-López
authors.forename: Higinio
authors.initials: H
authors.lastname: Arzate
mesh_terms: D002118:Calcium / Q000032:analysis; D003739:Dental Cementum / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D006801:Humans; D008274:Magnesium / Q000032:analysis; D010758:Phosphorus / Q000032:analysis
chemical_list: D010758:Phosphorus; D008274:Magnesium; D002118:Calcium