MAGNESIUM IN NEWLY FORMED DENTIN MINERAL OF RAT INCISOR

Small amounts of magnesium are always detectable in addition to calciu m and phosphorus in mineralized tissues such as dentin or bone, Magnes ium has been considered to influence the mineralization process, espec ially crystal growth. The present study reports on the location and en richment of magnesium in the newly mineralized dentin by using the hig h lateral resolution of energy dispersive X-ray microanalysis combined with scanning transmission electron microscopy. To this end, we have used the continuously growing rat incisor as a model for a collagenous mineralizing system. Dental tissue was dissected free and cryofixed i n liquid nitrogen-cooled propane. The distribution of elements was mea sured in freeze-dried ultrathin cryosections, The magnesium distributi on of the newly formed dentin area near the predentin area was found t o be inhomogeneous. In certain small dentin areas, characteristical ma gnesium enrichments were observed. Further, high magnesium-to-phosphat e molar ratios were found in these areas, and these were correlated wi th low calcium-to-phosphate molar ratios, Our results support the theo ry that magnesium is involved in the process of biological apatite cry stal formation.