Diabetes negatively affects tooth enamel and dentine microhardness: An in-vivo study

Objective: This study was performed to evaluate the effect of type 1 diabetes mellitus (T1DM) on the microhardness of tooth enamel and dentine in mice. Design: Seventy male C57BL/6 J mice were used in this study. Thirty-five mice were rendered diabetic by administration of streptozotocin (STZ), and the remaining animals received citrate buffer (normal/non-diabetic). In each group, specimens were divided into 7 subgroups of 5 mice based on the time points 0, 1, 4, 8, 12, 20, and 28 weeks. The microhardness value (MHV) of the second molars’ enamel and root dentine were tested with a Vickers microhardness tester. Five specimens from each subgroup were evaluated for dentinal tubular density by scanning electron microscope (SEM) and color dot map analysis to determine the color intensity of strontium (Sr) and magnesium (Mg) by using ImageJ software. Results: The MHV of enamel was significantly reduced in STZ specimens in time points of 12 weeks (STZ: 274.39 ± 15.42, normal: 291.22 ± 15.28), 20 weeks (STZ: 247.28 ± 19.65, normal: 290.68 ± 11.52), and 28 weeks (STZ: 232.87 ± 15.07, normal: 282.76 ± 10.36) (P < 0.05). When comparing the MHV of dentine in subgroups of the normal group, after 20 weeks (169.1 ± 7.5) and 28 weeks (168.6 ± 7.81), the MHV increased significantly (P < 0.05). However, in the STZ group, a significant reduction of MHV was noticed between 28 weeks (131.69 ± 6.2) specimens with other subgroups (P < 0.05). Conclusions: T1DM negatively affected enamel and dentine microhardness, and enamel was influenced much more negatively and rapidly compared with dentine in diabetic groups.