The effect of phenytoin medication on dentin apposition, root length, and caries progression in rat molars

Generalised stunting of roots in an epileptic child: is long-term phenytoin therapy the cause?

Long-term phenytoin therapy is known to cause disturbance in calcium and bone homeostasis. Dental tissues being calcified tissues can also be affected by this derangement of mineral metabolism, especially during developmental phases. This report describes a case of an epileptic child who presented with short roots, enlarged pulp chambers, blunt apices and delayed eruption of permanent dentition, which might be attributed to long-term phenytoin therapy. The purpose of this case report is to increase awareness among the clinicians about its possible dental implications and emphasise upon the need of regular dental check-ups in epileptic children.

Effects of continuous glucocorticoid infusion on the progression of dentinal caries in growing rats

This study was undertaken to test the effects of a low dose of continuous glucocorticoid infusion on the rate of progression of dentinal caries in molars of young rats. Forty-seven rats were inoculated in the mouth with Streptococcus sobrinus and fed ad libitum a cariogenic diet and 10% sweetened water. After 10 days of caries initiation ten animals were killed to serve as a reference group. In the rest of the animals the cortisone or placebo pellet was implanted subcutaneously in the back of the neck. The daily release of cortisone was 0.42 mg per rat. Sweetened water was changed to pure water, and the diet was the same cariogenic diet. After 6 weeks of medication the areas of dentinal caries were quantified planimetrically. Schiff's staining was used to classify caries. Although cortisone medication slightly increased the number of carious lesions, statistical significance was not reached. However, compared with the placebo group, the rats receiving cortisone medication showed significantly increased dentinal caries progression and severity of lesions. This study suggests that glucocorticoids with a cariogenic diet reduce the intrinsic modulation or response of the odontoblasts to caries attack.

A high sucrose diet decreases the mechanical strength of bones in growing rats

High sucrose diets alter mineral metabolism in humans and animals. We examined the effect of a high sucrose diet on bone growth, composition and mechanical strength in growing rats. Weanling Wistar rats received a high sucrose (43 g/100 g) diet (9 males, 11 females). In the control diet (8 males, 8 females), sucrose was replaced with potato starch, providing an equal energy value. At the onset of the experiment, bones were marked by tetracycline. After 5 wk, the tibias and femurs were weighed, and maximum breaking strengths were determined. Tibias were cut at the tibia-fibular junction; the widths of the bone at the start of the experiment, the periosteal bone formation during the experiment, the widths of the medullary cavity and the final bone width were determined from tetracycline lines. Bone ash weight, Ca and P contents were determined. The breaking strengths of both bones were significantly lower in the sucrose-fed groups of both sexes. In females, the weight of both bones and the final width of the tibias were significantly lower in the sucrose-fed group. The Ca concentration in both bones and the P concentration in tibias were significantly lower in the sucrose-fed group. It was concluded that the metabolic interference induced by sucrose was the reason for the differences. The alterations were more pronounced in females, but independent of body weight.

Greater concentration of dietary sucrose decreases dentin formation and increases the area of dentinal caries in growing rats

The effect of increasing dietary sucrose concentration on dentin formation and dentinal caries progression was studied. Weanling Wistar rats received 15, 30 or 43 g/100 g sucrose in a diet; for reference, another group was fed a nonpurified diet. At the onset, tetracycline was injected to mark the dentin formed during the experiment. After 6 wk, lower molars were sectioned sagittally; the areas and thicknesses of the dentin formation during the experiment and dentinal caries lesions were quantified separately in the first and second molars. Feeding the 43% sucrose diet resulted in a significantly lower dentin formation than in other diet groups (P < 0.05). The differences obtained from the area measurements were supported by thickness measurements. In the first molar, the 43% sucrose diet resulted in a significantly greater area of dentinal caries than in the other sucrose groups. The number and severity of caries lesions clearly increased as the concentration of sucrose in the diet increased (r = 0.5, P < 0.05 and r = 0.6, P < 0.05, respectively). This study suggests that the increase in the concentration of sucrose in the diet reduces dentin formation and increases the area of dentinal caries as well as the number and severity of caries lesions; the critical sucrose concentration appears to be between 30 and 43 g/100 g.

The effect of early weaning on dentin formation and dentinal caries in rats

The effect of early weaning on caries progression, dentin formation, and dentin mineralization was examined in four groups of rats. Two groups received a normal diet and were weaned on day 18 or 21, and another two received a sucrose-rich diet and were weaned on day 18 or 21. At age 35 days the lower molars were sectioned sagittally, and the areas of dentin formation and of the dentinal caries were quantified. The width of the predentin zone was measured from histologically stained sections of maxillary molars. Early weaning reduced dentin formation in the group on the high-sucrose diet only the first days; later this effect was partially caught up with. A high-sucrose diet significantly increased caries frequency and extension of caries lesions compared with a normal diet in both early weaned and normally weaned groups. The effect of early weaning on caries frequency and extension in the high-sucrose group was insignificant compared with the normally weaned group on a high-sucrose diet. The predentin zone was wider in the sucrose groups than in the control groups at the end of the experiment. These results indicate that the effect of sucrose on dentin formation was dependent on the stage of physiologic dentin formation, but early weaning as such did not affect this.

Chronic metabolic alkalosis, sucrose diet and dentine formation in young rats

As acid-base status has an effect on bone formation and remodelling, chronic metabolic alkalosis was induced in 3-week-old rats for 6 and 7 weeks with 0.25 mol/1 of NaHCO3 in their drinking water to determine whether it has any effect on dentinogenesis in the molars. One group of rats was fed a high-sucrose diet and the other two a standard diet. The control groups had the same diets but drank distilled water. All the rats were injected with tetracycline to mark the onset of dentine apposition. The alkalotic effect of the NaHCO3 drinking water was confirmed by blood gas analysis at the end of the experiment. After death, tetracycline-marked dentine apposition was measured from sagittally sectioned mandibular molars. Chronic metabolic alkalosis did not affect dentine apposition in the groups with the high-sucrose diet, nor in the groups with the standard diet at 6 weeks, but reduced it significantly in first and second molars in 7 weeks at rats on the standard diet. A high-sucrose diet alone caused a greater reduction in the amount of dentine. The general growth of the rats was not affected in any of the groups.

Effect of low-dose glucocorticoid treatment on dentin formation and dentinal caries in rats

The effect of a low dose of glucocorticoids on dentin formation and progression of dental caries was studied in young rats. The animals were inoculated in the mouth with Streptococcus sobrinus and fed ad libitum a high-sucrose, a high-starch, or a reference diet. The cortisone or placebo pellet was implanted subcutaneously in the back of the necks of the animals. After a 6-week experimental period the areas of dentin formation and dentinal caries were quantified planimetrically. Schiff's staining was used to classify caries. Cortisone reduced the dentin formation both in high-starch and reference diets, but it did not further affect the reducing effect of the high-sucrose diet on dentin formation. Cortisone did not affect the number or severity of dentinal carious lesions.

Effect of xylitol on dentin formation in molars of adult rats

A xylitol-induced reduction in dentin formation has been observed in molars of post-weanling rats, but the effect in older animals with a slower rate of secondary dentinogenesis has not been investigated. We examined the effects of different concentrations of dietary xylitol on dentinogenesis in molars of young adult rats. The control group received a commercial basal diet, while for the other 3 groups, the same diet was supplemented with 5, 10 and 20% of xylitol. After 8 weeks, dentin thickness beneath the main fissures in the mandibular 1st and 2nd molars was measured. The final body weights did not differ between the groups. Dentin formation in the 1st molars of the 10 and 20% xylitol groups was significantly lower as compared to the controls, whereas no difference was found between these 2 groups. In conclusion, dietary xylitol reduces dentin formation in young adult rats in spite of the slow rate of dentinogenesis.

Morphological analysis of dentine formation in young rat molars during the 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 injection. 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 labelling was repeated. Replenishment of the diet was introduced for Ca-deficient rats, and 10 received additional 5% xylitol in the diet. After 4 weeks the labelling was repeated and the animals were decapitated. Dentine formation was measured by the tetracycline stripes in the lower first and second molars. Calcium deficiency during the first 3 weeks 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-xylitol group and did not differ from the Ca-deficient period. These results indicate that in rat molars the odontoblasts can accelerate the rate of dentine formation when calcium is restored to the diet, at least during primary dentinogenesis. This effect was not seen when 5% xylitol was added to the replenishment diet.

Effect of sucrose and xylitol diets on dentin formation and caries in rat molars

To investigate the effects of a high sucrose diet and xylitol on secondary dentinogenesis and dentinal caries, a part of the sucrose in a high-cariogenic diet was replaced by xylitol. Fifty-four 3-wk-old Wistar rats were labeled with tetracycline and divided into groups. One group received a high sucrose diet (43% sucrose). In two other groups 5% and 20% of the sucrose was replaced by xylitol. A control group received non-cariogenic food. Six weeks later the mandibles were sectioned sagittally. Schiff staining was used to classify the caries, and the areas of dentin formed during the experiment and dentinal caries in first and second molars were measured planimetrically. The high sucrose diet reduced dentin formation of the molars, and this reduction was further increased by xylitol. Caries initiation and dentinal caries progression were significantly reduced by 20% xylitol, whereas only a slight reduction in caries progression was observed with 5% xylitol. Also, a negative correlation between the dentin formation and dentinal caries progression was observed in the high sucrose and 5% xylitol groups. In conclusion, xylitol together with high sucrose reduced dentin formation and dentinal caries progression, and the effect was dose-dependent.

The effect of ovariectomy and high-sucrose diet on dentine formation and caries in growing rats

Ovariectomized (Ovx) or sham-operated (Cnt) and tetracycline-labelled growing rats were fed either a commercial powdered standard rat diet (Ovx and Cnt) or a high-sucrose diet (Ovxsuc and Cntsuc). All animals were inoculated in the mouth with Streptococcus sobrinus. At 11 weeks of age the areas of caries lesions and dentinal apposition of the first and second molars and the areas of the pulpal cross-section of the incisors were determined. The area of dentinal apposition was largest in Cnt animals, the difference being statistically significant only in comparison with the Cntsuc animals. No such difference between the diets was found among the Ovx animals. The cross-section of the pulpal chamber was smallest in the Ovxsuc rats and largest in the Cnt animals, but no statistically significant differences were found between the groups. The caries lesions were significantly larger in Ovx, Ovxsuc and Cntsuc animals than in Cnt ones. Ovariectomy thus increased caries progression in growing rats, but the effect on dentine formation remained negligible. In this respect there is a difference between primary and secondary dentinogenesis.

Reduction in dentine apposition in rat molars by a high-sucrose diet

The effects of high-sucrose and high-starch diets on dentine apposition were examined. One group of young Wistar rats (20 rats) received a high-sucrose (43%) diet; for the high-starch group (16 rats), sucrose was replaced with potato flour. The control group (18 rats) received standard laboratory rat food. The onset of dentine formation was marked with tetracycline. After 5 weeks lower molars were sectioned sagittally, and the areas of the dentine apposition and those of the dentinal caries were quantified. Dentine apposition was independent of sex. The high-sucrose diet reduced dentine apposition and induced caries progression. A negative correlation between dentine apposition and caries progression in the molars was found. This study suggests that a high-sucrose diet itself reduces primary dentine apposition.