Objective To study the benchmark dose (BMD) of fluoride concentration in saliva,and to evaluate the significance of saliva fluoride on control and prevention of endemic fluorosis.Methods In September 2014,middle school students in endemic fluorosis areas and non-endemic fluorosis areas in North China Petoleum were selected as objects.The contents of fluoride in water,urine and saliva were determined.The correlation of fluoride content in water,urine fluoride and fluoride concentration in saliva was analyzed.According to the levels of the saliva fluoride concentration,the children were divided into 11 groups,＜ 1.00,1.00-,2.00-,3.00-,4.00-,5.00-,6.00-,7.00-,8.00-,9.00-and ≥ 10.00 mg/L.The prevalence of dental fluorosis and defected dental fluorosis were investigated and the saliva fluoride concentration was calculated by Banch-Mark Dose Software.Results Compared with non endemic areas,the fluoride contents in water,urine and saliva [(2.13 ± 0.13),(1.29 ±0.73),(4.01 ± 3.61) mg/L] were higher than that in endemic areas [(0.67 ± 0.13),(0.38 ± 0.08),(0.75 ± 0.12) mg/L,t =158.730,24.780,18.114,all P ＜ 0.01].The fluoride concentration in saliva was positively correlated with the fluoride content in water and urine in endemic areas (r =0.626,0.945,all P ＜ 0.01).The (BMDs and benchmark dose lower bound (BMDLs) were 0.91,0.54,3.72,3.32 mg/L respectively,calculated by Banch-Mark Dose Software.With the increase of fluoride concentration in saliva,the prevalence of dental fluorosis and defect dental fluorosis had increased too,especially when the fluoride content in saliva was more than 4 mg/L.There were significant doseresponse relationships between the urine fluoride and the prevalence of dental fluorosis and defected dental fluorosis.Conclusion The fluoride concentration in saliva could be used as one of the evaluation indexes of fluorosis,and the BMD of saliva fluoride concentration in endemic fluorosis areas is suggested as 0.91 mg/L.

Objective:To study the effects of dental fluorosis on the tooth movement following extraction of adjacent tooth in adoles-cents for orthodontic treatment.Methods:50 adolescents were divided into mild(n =1 3),moderat(n =1 0),severe(n =7)and healthy control(n =20)groups according to the fluorosis severity using Dean's index.4 4 were extracted and appliance was applied. X-ray image was taken 1 week and 1 ,2 and 3 months after appliace activation.Tooth movement was measured cephalometrically by Auto CAD.Results:Tooth moving distance was more(P <0.01 )and the alveolar bone resorption area was smaller in fluorosis group than those in healthy control group(P <0.01 )1 ,2 and 3 months after appliance activation.The moving distance was negativelly relat-ed with bone remodling area(P <0.05).Conclusion:Adolescent dental flurosis play an important role in bone remdodeling in extra-tion sites and tooth movement during orthodontic treatment.

Objective The purpose of this study was to study the correlation between dental fluorosis, saliva and plaque fluoride levels and urinary fluoride values in adolescents dental fluorosis. Methods A middle school was chosen as a survey point in the study. Two hundred adolescents were examined the degree of dental fluorosis by Dean's method. These adolescents were divided into four groups according to the severity of fluorosis (n = 52, 40, 28 and 80). Fluoride ion specific electrode was used to measure the fluoride levels in dental plaque, saliva, urinary and drinking water. The differences were analyzed b y ANOVA. Correlation of the fluoride levels between dental plaque, saliva, urine and the degree of dental fluorosis were analyzed by the method of multiple linear regression. Results The average fluoride content of drinking water was (2.20 ± 0.40) mg/L. Compared with controls, the fluoride concentrations in dental plaque, saliva and urine were higher in light, medium and severe dental fluorosis groups [(1.55 ± 0.88), (1.94 ± 0.77), (2.74 ± 0.83) than (0.32 ± 0.20) mg/L; (4.44 ± 1.62), (8.09 ± 0.93), (10.72 ± 0.99) than (0.02 ± 0.01) mg/L;(31.77 ± 6.09), (57.98 ± 1.83), (65.98 ± 2.78) than (13.06 ± 2.11) μg/g, all P<0.05]. Urinary fluoride was correlated with fluoride in saliva and dental plaque (r=0.245, 0.440, all P<0.05). Saliva fluoride was correlated with fluoride in dental plaque (r=0.849, P<0.01). The degree of dental fluorosis was correlated with fluoride in urine and saliva (r = 0.497, 0.896, 0.924, all P< 0.01). The multiple linear regression equation between fluoride in urine and the degree of dent al fluorosis, fluoride in dental plaque and saliva was as follow: y = 1.357 + 1.618x1 + 0.001x2 - 0.331x3 ± 0.69. Conclusions The metabolism of fluoride in body is related with oral fluoride repository in adolescents dental fluorosis. Fluoride in urine is influenced by plaque fluoride level, saliva fluoride concentration and the degree of dental fluorosis.