The animals were maintained in cages under natural 12 h light/dark cycles. Water (fluoride level: 0.351 mg/l) and food were given ad libitum during the experiment. In order to examine the level of fluorosis in the rats semiquantitatively, the degree of the rats’ dental fluorosis was evaluated using the 0–5 scoring method described by Boulton et al. (1995) and Ekambaram and Paul (2002). The experimental procedure was approved by the Ethics Committee of the Faculty of Medicine, Universitas Gadjah Mada (approval no. KE/FK/ 224/EC).