Effect of the Contraceptive Steroids Norethynodrel and Mestranol on Dental Caries Activity in Young Adult Female Rats

Abstract

Norethynodrel and mestranol in a ratio identical to that used for contraception were injected subcutaneously daily for five weeks into young adult female rats. These rats were fed with a purified caries test diet. The various lesions of the treated rats increased proportionately with increased doses of the agents.In previous studies, it was observed that the administration of some oral contraceptive steroids caused an increase in dental caries activity in female rats when a caries test diet was composed principally of coarse rice particles and powdered whole milk.1,2 Thus, the various lesions were observed only in the sulci. Furthermore, the steroid treatments were begun when the rats were 22 days of age, at which age the molars were more susceptible to caries attack.3 In the present study, we tried to determine whether these steroids would still be cariogenic under the following experimental conditions: (1) a purified caries test diet, ad libitum, beginning at 21 days of age; (2) steroid treatments begun at 50 days of age, that is, after the rats attained puberty, which occurs at about 35 days of age; and (3) steroid doses similar to and greater than those used for contraception in female rats. Materials and MethodsWeanling female rats of the SpragueThis paper was presented at the 50th General Session of the IADR in Las Vegas, Nev, March 1972. Dawley strain were separated randomly into three groups and were supplied, ad libitum, with a caries test diet4 of MIT diet no. 200b and distilled water. They were housed in individual suspended hardware cloth cages at a room temperature of 72 + 1 F and light exposure was controlled automatically between 6:00 AM and 6:00 PM. Beginning at 50 days of age, rats in the first test group received daily (except Saturdays and Sundays) subcutaneous injections of 100 jig norethynodrele plus 4 ftg mestranole in steroid diluent. These steroid doses were given on a body weight basis. Norethynodrel(1 7a-ethynyl-1 7,8-hydroxy 5 (10) -estren-3-one) and mestranol (17-ethynyl-estradiol 3-methyl ether) are, respectively, synthetic progestogenic and estrogenic steroids. Rats in the second test group were injected at similar intervals with four times the amount of these steroid doses; the control rats were given the steroid vehicle alone.At 85 days of age, all rats were killed by chloroform inhalation. The final body and organ weights of ten rats from each group were measured immediately. All the heads were autoclaved and the attached soft tissues then were removed. Dental caries was assessed by the method of Keyes,5 except that the molars were stained with Schiff's reagent.6 Body and organ weights and dental carious lesions of both treated groups of rats were compared with those of the controls by Student's t test at a 5% level of significance. ResultsThe mean number carious enamel regions of combined smooth surface lesions and

Explaining sex differences in dental caries prevalence: Saliva, hormones, and “life‐history” etiologies

“…The effect of estrogens on the rate of caries was further increased when androgens were removed from the blood circulation entirely by removal of the gonads, the glands responsible for androgen production. Several researchers replicated this study, and their research confirmed that estrogen levels are positively correlated with caries rates, and that androgens have no effect (Delman, 1955;Laine et al, 1988;Liu and Lin, 1973;Legler and Menaker, 1980).…”

“…Clinical studies document the strong inverse correlation of salivary flow rate and dental caries rate (Bergdahl, 2000;Dowd, 1999;Valdez et al, 1993). However, one life-history event-pregnancypresents an extreme case of hormonal fluctuation, and further illustrates the causal link between estrogen and caries rate (Delman, 1955;Laine et al, 1988;Legler and Menaker, 1980;Liu and Lin, 1973;Muhler and Shafer, 1955;Orosz et al, 1975;Vadiakas and Lianos, 1988).…”

“…Animal research was also used to elucidate the mechanism by which increased estrogen Angsusingha et al (1974), Liu and Lin (1973), Mikhail et al (1970), Muhler and Shafer (1955), Ngai and Longcope (1971), Shafer and Muhler (1954), Wright, et al (1973), and Wu and Lundy (1971). levels lead to increased caries rates.…”

Sex and Gender Related Health Status Differences in Ancient and Contemporary Skeletal Populations

“…Among the reasons for the higher female rate of caries are hormonal fluctuations (Lukacs and Largaespada 2006). A growing body of research reveals that caries rates increase proportionally with increasing oestrogen levels (Liu and Lin 1973;Legler and Menaker 1980;Shafer and Muhler 1954), which are higher in females throughout the life cycle and significantly higher during puberty, pregnancy and menstruation (Angsusingha et al 1974;Niswender et al 1976;Worthman 1995). Fluctuation in the level of oestrogen influences thyroid activity and leads to reduction of saliva flow rate (Muhler and Schafer 1955), which impacts on oral health (Tenovuo 1997(Tenovuo , 1998.…”

Caries prevalence and oral contraception

“…It has been suggested that oral contraceptives can increase the caries rate in rats (3), thus a pilot study was conducted to investigate the relationship betweeti human caries prevaletice and usage of different oral contraceptive formulations.…”