Histological investigation of the effects of nano titanium dioxide on the development of the first mandibular molar bud in NMRI mouse strain in vivo

Nowadays, with the applications of titanium dioxide nanoparticles (TiO2-NPs) in pharmacy, food industry, cosmetics, toothpaste and sunscreens, pregnant women are exposed to nanoparticles. Since tooth development is vuln-erable to environmental impacts and mandibular first molar bud develops before maxillary first molar bud, in this ex-perimental study the effects of TiO2-NPs on the development of first mandibular molar bud in NMRI mouse was inve-stigated. Twenty five female NMRI mice were randomly divided into five groups (N=5); Control group (pregnant mice without any treatment), sham group (treated with distilled water), experimental groups 1, 2 and 3 (treated with 50, 150 and 500 mg/kg BW TiO2-NPs, respectively, via gavage from embryonic days 10.5-14.5). On E14.5, embryos heads were prepared for histological examination and dental tissues were evaluated. Data were analyzed by ANOVA and post hoc test (Tukey). Microscopic observation showed tissue disorganization in experimental groups. Findings showed that in experimental groups 1 and 2, the diameter of bud and dental papilla and the length of dental bud decreased sign-ificantly. In experimental group 2, decrease in the diameter of dental follicle, dental bud and dental papilla and the le-ngth of dental bud was significant. On the other hand, in experimental group 3, only the decrease in the length of dental bud was significant. These findings showed that nano titanium dioxide can reduce the size of dental buds and is capable of preventing tooth development.