Sixty, adult healthy Kunming mice, were obtained from the Experimental Animal Center of Shanxi Medical University (Taiyuan, China). After one-week of acclimatization, the mice were randomly divided into control group (drinking deionized water) and NaF treated groups (concentration of F ion in deionized water: 68 mg/L). Throughout the whole the experiment, mice were kept in quiet, hygienic, temperature-controlled environment under controlled lighting (12 h light: 12 h dark). Deionized water and commercial rodent pellets were freely accessed all the time. All animal procedures were performed in compliance with the regulations and guidelines of International Ethics Committee on animal welfare. Mice were observed every day and weighed once for every two weeks. Mice were exposed to NaF for three different exposure periods like 90 days, 120 days and 150 days.

Sixty, adult healthy Kunming mice, were obtained from the Experimental Animal Center of Shanxi Medical University (Taiyuan, China). After one-week of acclimatization, the mice were randomly divided into control group (drinking deionized water) and NaF treated groups (concentration of F ion in deionized water: 68 mg/L). Throughout the whole the experiment, mice were kept in quiet, hygienic, temperature-controlled environment under controlled lighting (12 h light: 12 h dark). Deionized water and commercial rodent pellets were freely accessed all the time. All animal procedures were performed in compliance with the regulations and guidelines of International Ethics Committee on animal welfare. Mice were observed every day and weighed once for every two weeks. Mice were exposed to NaF for three different exposure periods like 90 days, 120 days and 150 days.

Sixty, adult healthy Kunming mice, were obtained from the Experimental Animal Center of Shanxi Medical University (Taiyuan, China). After one-week of acclimatization, the mice were randomly divided into control group (drinking deionized water) and NaF treated groups (concentration of F ion in deionized water: 68 mg/L). Throughout the whole the experiment, mice were kept in quiet, hygienic, temperature-controlled environment under controlled lighting (12 h light: 12 h dark). Deionized water and commercial rodent pellets were freely accessed all the time. All animal procedures were performed in compliance with the regulations and guidelines of International Ethics Committee on animal welfare. Mice were observed every day and weighed once for every two weeks. Mice were exposed to NaF for three different exposure periods like 90 days, 120 days and 150 days.