O efeito da febre na mineralização do esmalte dentário: um modelo murino

Abstract

Molar-Incisor Hypomineralization aetiology is still unknown, but it has been associated with fever in childhood. This study aimed to evaluate the fever effect on enamel mineralization of lower incisors of C57Bl/ 6 strain mice. Animals were divided into two groups: 6 in the experimental and 6 in the control. A dose of 12 ml/ Kg of 15 % w/v of brewer yeast and 12 ml/ Kg of saline was subcutaneous injected into each experimental and control mouse, respectively, twice a day for three consecutive days. The body temperature was measured, using a digital thermometer, immediately before the injections and 3, 6 and 10 hours after the injections. Considering a tooth eruption rate of 0.18 ± 0.05 mm per day, the animals were sacrificed 15 days after the first injection. Elemental analysis of the enamel was done using Micro X-ray fluorescence (μXRF). The mapping of the enamel surface analyzed the spatial distribution of Ca, P, Fe and Sr. The quantification of minerals (Ca, P, Sr, Fe, Zn, and Ca:P) was done in two points positioned in the mature enamel and two points in the maturing enamel. Mann Whitney test was used to compare the body temperature before and after the injections as well as to compare the mineral quantity between the experimental and control groups. The mean body temperature of the experimental and control groups before the first injection were 35.9 ± 0.1 ºC and 35.9 ± 0.2 ºC, respectively. The average body temperature of the experimental and control groups after the first injection were 37.4 ± 0.3ºC and 36.3 ± 0.2ºC, respectively. In the experimental group, Fe was concentrated in the incisal third, while in the control group it was distributed along the incisal and medium thirds of the enamel surface. No significant difference was observed in the quantities of Ca, Fe, Zn, and Ca:P ratio between groups. The experimental group showed a higher concentration of P in the maturing enamel (p = 0.02) and a lower concentration of Sr in the mature (p = 0.01) and maturing enamel (p = 0.006). Therefore, this study suggests that fever can disturb ion movement through tight junctions of ameloblasts, modifying the enamel mineralization of lower incisors of C57Bl/ 6 strain mice.