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Objective To observe the maxillary alveolar cortical bone and cancellous bone mineral density of patients with different degree of dental fluorosis.Methods According to the diagnostic criteria of dental fluorosis (WS/T 208-2011),from March 2015 to March 2017,30 orthodontic dental fluorosis patients were selected in Guiyang Stomatological Hospital.According to the degree of tooth damage,patients were divided into mild,moderate and severe fluorosis groups,10 cases per group;10 normal orthodontic patients were selected as control group.A cone beam computed tomography (CBCT) was taken preoperatively to measure the CT values (the attenuation value after absorption of X-rays through the tissue,HU) of buccal alveolar cortical bone and cancellous bone density in incisor,canine,premolar,and molar areas.Results The buccal alveolar cortical bone densities of incisor [(1 155.6 ± 80.7),(1 048.8 ± 106.7),(885.1 ± 118.1),(589.7 ± 104.6) HU],canine [(1 221.0 ± 76.l),(1 054.6 ± 95.3),(913.3 ± 109.4),(608.5 ± 131.4) HU],premolar [(1 173.5 ± 91.2),(1 020.9 ± 113.3),(894.5 ± 107.9),(593.5 ± 119.7) HU],and molar [(1 113.6 ± 89.5),(1 017.2 ± 101.3),(877.2 ± 102.9),(609.1 ± 113.5) HU] areas in control,mild,moderate and severe fluorosis groups,were significantly different statistically (F =45.557,51.411,61.200,56.845,P ＜ 0.01),CT values of dental fluorosis group were significant lower than that of control group (P ＜ 0.05).The cancellous bone mineral density of the incisor [(633.4 ± 67.7),(556.8 ± 80.1),(473.1 ± 71.7),(358.8 ± 98.7) HU],canine [(644.9 ± 70.1),(570.6 ± 73.3),(490.0 ± 85.2),(361.1 ± 93.8) HU],premolar [(630.5 ± 72.5),(554.5 ± 70.7),(477.7 ± 84.0),(353.6 ± 101.4) HU],and molar [(637.6 ± 79.8),(558.5 ± 84.3),(471.7 ± 72.8),(367.7 ± 88.7) HU] areas in control,mild,moderate and severe fluorosis groups,were significantly different statistically (F =20.183,20.245,22.751,21.268,P ＜ 0.01),CT values of dental fluorosis group were significant lower than that of control group (P ＜ 0.05).Conclusion The bone density of maxillary alveolar cortical bone and cancellous bone is reduced in dental fluorosis patients.
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Objective To study the influence of parental generation coal-burning-borne fluorosis on tooth development of their offspring.Methods High fluoride air model was established on the basis of burning coal habit of the epidemic areas.Fluoride feed was made of coal drying corn from the epidemic areas.Totally 48 SD rats were randomly divided into 4 groups with male to female ratio of 1:1 by random number table method.Rats in high,middle and low fluoride groups were put in the high fluoride air room and feed food with 40,25 and 10 mg/kg fluorine,and the control group was put in normal air room and feed normal food.After 8 weeks,rats were mating and parturition.Tooth eruption time of offspring rat was observed;and dental fluorosis incidence,the tooth length and fluorine content were observed at 21 d.Results In high and middle fluoride groups [(6.83 ± 0.94),(6.25 ± 1.06) d],tooth eruption time of offspring rat was later than that of control group [(5.34 ± 0.89) d,all P ＜ 0.01].At 21 d,dental fluorosis was observed in the lower incisors of the high and middle fluorine groups;compared with control group [(5.21 ± 0.19) mm,(223.00 ± 14.08) μg/kg],the tooth length was decreased [(4.83 ± 0.22),(4.96 ± 0.25) mm,P ＜ 0.01or ＜ 0.05],and tooth fluoride content was increased [(362.64 ± 20.35),(289.79 ± 19.18) μg/kg,all P ＜ 0.01].Dental fluorosis incidence of offspring rats was positively correlated with the fluorine dose (r =0.704,P ＜ 0.01).Conclusion Parental generation rats’ intaking excessive fluoride can affect offspring rats tooth development and dental fluorosis,which is related to the fluorine dose.
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Objective To establish a fluorosis model induced by coal burning and in ameloblasts of rat offsprings.Methods High fluoride air model was established based on the burning coal habit of the epidemic areas.Fluoride feed was made of corn dried by coal burning.Thirty-six SD rats were divided into 3 groups by random number table method according to body weight in a male and female ratio of 2 ∶ 1∶ in the high fluoride air room and rats were feed food with fluorine at 40 mg/kg (high fluoride group),25 mg/kg (low fluoride group);in the normal air room and rats were feed food with fluorine at 0 mg/kg (the control group),12 rats in each group.Mating litter in a ratio of 2 ∶ 1 at the end of 8 weeks.The offsprings were killed on postnatal day 3 and 7 to make mandible sections.Specimens were prepared for light microscope examination to observe the morphological changes of ameloblasts in the tooth germ.Results At the end of 0,2,4,6 and 8 weeks,serum fluoride of the high fluoride group were (0.031 ± 0.003),(0.060 ± 0.006),(0.085 ± 0.006),(0.110 ± 0.007) and (0.134 ± 0.008) mg/L;serum fluoride of the low fluoride group were (0.031 ± 0.003),(0.046 ± 0.005),(0.077 ± 0.006),(0.091 ± 0.007) and (0.104 ± 0.007) mg/L;serum fluoride of the control group were (0.030± 0.003),(0.037 ± 0.002),(0.044 ± 0.002),(0.046 ± 0.003) and (0.049 ± 0.003) mg/L.At the end of 2,4,6 and 8 weeks,serum fluoride of high fluoride group and low fluoride group were significantly higher than that of control group (all P ＜ 0.05).At 7 d,offspring rats in high fluoride group,adamantoblasts were in distortions and vacuole changes,but offspring rats in low fluoride group and the control group had no abnormality.Conclusion By providing rat with high fluoride air and food,we could establish a fluorosis model induced by coal burning in ameloblasts of rat offsprings.
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<p><b>OBJECTIVE</b>To evaluate the operation time and clinical effect of three types of materials (i.e., total-etching adhesive, self-etching adhesive, resin-modified glass ionomer cement) that are used to bond removable thermoplastic appliances.</p><p><b>METHODS</b>Thirty malocclusion patients (156 attachments) with removable thermoplastic appliances were randomly divided into three groups, with 10 individuals each. Attachments of groups A and B were bonded using 3M Adper Single Bond 2 and 3M Adper Easy One, respectively; both adhesives utilized 3M Z350 nano composite resin. Attachments of group C was directly bonded using GC Fuji Ortho LC. The operation time of each attachment was recorded. Failure rates of adhesion were evaluated during adhesion, 1 month after treatment, and 6 months after treatment.</p><p><b>RESULTS</b>The operation time of group C was shorter than those of groups A and B (P<0.01). Significant difference of adhesion failure rates was not found among the three groups (P>0.05). No significant difference of adhesion failure rates was also observed in different times of the same group (P>0.05).</p><p><b>CONCLUSION</b>The attachment stability of the three types of materials achieved satisfactory effects. However, the operation method of resin-modified glass ionomer cement is more concise and suitable for clinical promotion.</p>