MORPHOLOGICAL ANALYSIS OF DENTIN FORMATION IN YOUNG-RAT MOLARS DURINGTHE RECOVERY PHASE WITH CALCIUM ALONE OR COMBINED WITH XYLITOL FOLLOWING A LOW-CALCIUM DIETARY REGIMEN

The effects of dietary calcium deficiency and subsequent replenishment of the diet with calcium alone or with xylitol were studied. Thirty 3 -week-old Wistar rats were labelled with an i.p. tetracycline injectio n. Twenty rats were fed a diet with 0.026% calcium (Ca-deficient); 10 received a 0.5% Ca diet (controls). After 3 weeks the tetracycline lab elling was repeated. Replenishment of the diet was introduced for Ca-d eficient rats, and 10 received additional 5% xylitol in the diet. Afte r 4 weeks the labelling was repeated and the animals were decapitated. Dentine formation was measured by the tetracycline stripes in the low er first and second molars. Calcium deficiency during the first 3 week s reduced dentine formation. In the control and xylitol groups, a much smaller amount of dentine was formed during the recovery period. With Ca alone, dentine formation was faster than in the controls or Ca-xyl itol group and did not differ from the Ca-deficient period. These resu lts indicate that in rat molars the odontoblasts can accelerate the ra te of dentine formation when calcium is restored to the diet, at least during primary dentinogenesis. This effect was not seen when 5% xylit ol was added to the replenishment diet.