Salivary Magnesium Levels in Pregnant Women J. KAYAVIS and P. PAPANAYOTOU Department of Stomatology, School of Dentistry, University of Thessaloniki, Thessaloniki, Greece Magnesium analysis by atomic absorption spectrophotometry was done on stimulated saliva samples obtained from 294 pregnant and 160 nonpregnant women. The participants ranged from 20 to 30 years of age. In the pregnant group, 20 women were in the third month, 23 in the fourth month, 50 in the fifth month, 50 each in the sixth, seventh, and eighth months, and 51 in the ninth month of pregnancy. After fasting, stimulated whole saliva was obtained while the women chewed 2 gm of clear paraffin. The collected specimens were centrifuged for 15 minutes at 3,500 rpm to obtain 2.5 ml of clear saliva, which was mixed with distilled water in a 1:10 ratio. Magnesium estimation was done with the double-beam atomic absorption spectrophotometer.a Atomic absorption is the method of choice (ALLAN, Analyst 83: 466-477, 1958) for magnesium and has been used for salivary magnesium estimations (Gow, J Dent Res 44: 890-894, 1965). The magnesium tube was operated at a current of 12 amp and the absorption band was 2,852 A. The pressure of the gases was set at 9 lb/in2 for acetylene and 30 lb/in2 for air. The values obtained showed higher concentrations of magnesium in the saliva samples of the pregnant women than in those from the nonpregnant group (Table). The difference in mean values was statistically significant. The lowest mean value was found in the group in the fourth month of pregnancy (mean, 0.57 mg/ 100 ml; SE -+ 0.05), and the highest was in the ninth month (mean, 0.72 mg/l00 ml; SE 0.05). However, this difference was not statistically significant (P > 0.1) . '

Received for publication June 10, 1975. Accepted for publication January 19, 1976. Perkin-Elmer 403 double-beam atomic absorption spectrophotometer, Perkin-Elmer Corp., Norwalk, Conn. a

Our search of the literature indicates that the salivary magnesium level of pregnant women has not been studied extensively. Before the present study, only Becks (Proc Soc Exp Biol Med 26: 93-95, 1928) had reported that salivary magnesium levels increase in pregnancy. This increase is not readily explained because of incomplete knowledge of magnesium metabolism. However, it is known that the alkaline phosphatase level, activated by magnesium (KING, Practical Clinical Enzymology, 1965), increases in the saliva of pregnant women (PAPANAYOTOU, Contribution in the Study of Salivary Alkaline Phosphatase in Pregnant Women, PhD thesis, 1969). Thus, it can be postulated that because of the association between magnesium and alkaline phosphatase, the increase in the magnesium level is a function of the increased alkaline phosphatase level in the saliva of pregnant womeni. It has been further observed that the level of tissue magnesium is increased and the level of plasma magnesium is decreased by estrogen (GOLDSMITH, 1st Int Symp on Magn Def in Hum Pathol, 1971). Although this could support anlother hypothesis for the increased magnesium level, -the mechanism is again obscure because information is lacking on the relationships of magnesium and endocrine changes. Finally, it is at least conceivable that the increased magnesium level being mainly an intracellular ion (HArEMI and TUMAY, Pediatrie 5: 535-538, 1969) is related to the increased desquamation of oral mucosa during pregnancy. Changes in the levels of salivary magnesium could be of great clinical interest because of their relation with eclampsia (PRITCHARD, Gyn? ecol Obstet 100: 131-140, 1955) and the offspring (HURLEY, Ist Int Symp on Magn Def in Hum Pathol, 1971), but further studies on magnesium metabolism will be required to clarify these associations.

TABLE SALIVARY MAGNESIUM LEVELS IN 294 PREGNANT AND 160 NONPREGNANT WOMEN

Mean

Pregnant women Nonpregnant women

Range

(mg/100 ml)

(mg/100 ml)

0.63 0.50

0.20-3.23

0.20-1.40

Standard Error

(mg/I00 ml) + 0.02

± 0.01

Note: For the mean, P < 0.001.

706

J Dent Res July-August 1976, Vol 55 No. 4

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