ObjectiveTo observe the morphological changes of bone in the progress of chronic fluorosis.MethodsWistar rats were randomly divided into three groups,30 rats in each group:normal control group,experimental group Ⅰ and experimental group Ⅱ according to body weight.Rats in normal control group drank distilled water freely.Experimental group Ⅰ and group Ⅱ drunk distilled water with sodium fluoride preparation of fluorine containing ion 100,150 mg/L solution for six months,respectively.Bone mineral density was detected by X-ray,bone morphological changes were observed under light microscope and bone histomorphometric parameters were calculated using image analysis software.ResultsThe bone mineral density values were different statistically between the three groups after feeding for 2 and 4 months(F =19.79,3.28,all P ＜ 0.05).However no significant difference was found after feeding for 6 months(F =1.80,P ＞ 0.05).The bone mineral density of experimental group Ⅰ (0.20 ± 0.03,0.21 ± 0.03) was significantly higher than that of the normal control group(0.17 ± 0.03,0.20 ± 0.04) after feeding for 2 and 4 months.The bone mineral density of experimental group Ⅱ (0.21 ± 0.02) was lower than that of normal control group(0.22 ± 0.03) after feeding for 6 months.The bone lamella in experimental group Ⅰ was arranged disorderly,the number of osteocytes increased with their nucleus atrophy and the osteoblasts were more than that of control grouo which arranged in layers observed under light microscooy.In exoerimental group Ⅱ,the bone lamella was bent deformation,the number of osteocytes had decreased with their nucleus shrinking or even disappeared and the number of osteoclasts had increased significantly observed under light microscopy.In experimental group Ⅰ,the mean trabecular density [(0.33 ± 0.03)％] increased and the mean trabecular separation,thickness [( 163.57 ± 1.99),(59.26 ± 7.18 ) μm] decreased compared with that of normal control group [(0.31 ± 0.02)％,(186.60 ± 2.90)μm,(86.42 ± 1.48)μm,all P ＜ 0.05].In experimental group Ⅱ,the mean trabecular density[(0.26 ± 0.02)％] decreased,the mean trabecular thickness[(71.42 ± 10.77)μm] reduced compared with that of normal control group[(0.31 ± 0.02)％,(86.42 ± 1.48)μm].ConclusionsExcess fluoride can damage bone tissue.Low doses of fluoride can stimulate osteoblast activity and enhance osteogenesis.The activity of osteoblasts is great than that of osteoclasts.High doses of fluoride can stimulate both osteoblasts and osteoclasts activity,but mainly the activity of osteoclasts,and bone resorption increases.

ObjectiveTo detect the concentration and distribution of fluoride ions in osteoblasts exposed to fluoride in vitro culture,and to provide basic information for studying the effect of fluoride on osteoblast injury.MethodsIn vitro cultured osteoblasts were exposed to 0,5,10,20,40 mg/L fluoride for 3,10,30 d (n =6),respectively.Concentration and distribution of fluoride ions in the cytoplasm and the nucleus of these osteoblasts were determined by nuclear magnetic resonance spectroscopy.Results(①) After cultured for 3 d,fluoride ion content of the bone cytoplasm exposed to different concentrations of fluoride 0,5,10,20,40 mg/L were (0.83 ±0.65),(0.54 ± 0.23),(0.65 ± 0.77),(0.59 ± 0.87),(3.64 ± 1.21 )mg/L,respectively,and the values of exposed to 40 mg/L fluoride group was significantly higher than that of exposed to 0,5 mg/L groups (all P ＜ 0.05).(②)after cultured for 10 d,the composition of the fluoride ion in cytoplasm of exposed to fluoride 10,20,40 mg/L groups were (4.03 ± 1.23),(3.66 ± 0.98),(6.26 ± 2.10)mg/L,respectively,which were higher than that of exposed to 0,5 mg/L groups [(0.78 ± 0.75),(2.69 ± 0.89)mg/L,respectively,all P ＜ 0.05].Of fluoride 20,40 mg/L groups,the composition of the fluoride ion in nucleus were (1.63 ± 1.19),(2.17 ± 1.21 )mg/L,respectively,which were higher than that of 0,5 mg/L groups[(0.65 ± 0.46),(1.57 ± 0.33) mg/L,all P ＜ 0.05].(③)After cultured for 30 d,of the exposed to fluoride 10,20,40 mg/L groups,the composition of the fluoride ion in cytoplasm were (3.99 ± 0.84),(4.33 ± 1.67),(5.80 ± 1.38)mg/L,respectively,which were higher than that of 0,5 mg/L groups[(0.88 ± 0.44),(2.84 ± 0.43)mg/L,all P ＜ 0.05].The composition of the fluoride ion in nucleus of the fluoride 20,40 mg/Lgroups were (3.33 ± 1.46),(3.53 ± 1.22)mg/L,respectively,which were significantly higher than that of 0,5mg/L groups [(0.70 ± 0.66),(1.99 ± 0.76)mg/L,all P ＜ 0.05].ConclusionsWhen osteoblasts are exposed to fluoride environment,fluoride ions enter into the osteoblasts quickly,and quickly accumulate in the nucleus,showing a special affinity between fluoride and bone tissue.Intracellular fluoride ions increase with the increase of contact time and exposure dose.