RESUMO
Objective To improve the load resistance ability of students in teenager aviation schools and carry out specialized training for the body situation and shape of students.Methods We selected students from 14 teenager aviation schools and measured their height,weight,and the circumferences of necks,chests,upper-arms,waists,hips,and thighs.We compared the data of these students from different areas and the parameters were analyzed statistically by correlation analysis.Results Totally 411 students from 6 southern schools and 403 students from northern schools were investigated.Their average body height,weight and body mass index (BMI) were (172.3 ± 4.39) cm,(62.7 ± 7.3) kg,and (21.1 ± 2.23)kg/m2 respectirely.Students from northern schools were taller and heavier than those from southern schools (P ＜ 0.05).There was no difference between students from northern and southern schools in BMI.Compared with the domestic average levels of height,weight and chest circumference of teenagers aged 14 to 17,students of teenager aviation schools were higher,but there was no difference in weight or chest circumference.The average circumferences of the chest,neck,left upper-arm,right upper-arm,waist,hip,left thigh and right thigh were (83.1 ± 5.06),(34.7 ±3.07),(25.2±2.33),(25.5 ±2.30),(73.4 ±6.73),(89.7 ±5.89),(50.1 ±5.22),and (50.2 ±5.27)cm,respectively.According to the data,students from northern schools had a bigger chest circumference and thigh circumference but a smaller neck circumference and upper-arms circumference than those from southern schools (P ＜ 0.05).The correlation coefficient between BMI and the circumferences of the chest,neck,left upper-arm,right upperarm,waist,hip,left thigh and right thigh was 0.2201,0.1066,0.2466,0.2499,0.2291,0.2149,0.2299,0.2264,respectively.All of them were statistically significant (P ＜ 0.0001).Conclusion Load resistance related parameters of students in teenager aviation schools are not different from the domestic levels,which points to the urgent need for load resistance ability training for these students.Some parameters vary between areas.BMI is positively related to those load resistance parameters.Based on regional variations and regularities found in this study,specialized load resistance ability training could be made more efficient.
RESUMO
BACKGROUND: Most studies suggest tooth whitening can create a coarse enamel surface which is likely to attract exogenous dyeing material and form the phenomenon of color relapse. After dental bleaching procedure, the use of resin surface treatment agent is expected to make the enamel surface smooth and alleviate tooth color relapse. OBJECTIVE: To unravel the efficacy of Adper Single Bond 2 Adhesive on color relapse phenomenon after dental bleaching treatment by cold light (xenon laser) whitening.METHODS: Twenty-four extracted teeth were collected and coated with 35% hydrogen peroxide followed by xenon laser whitening. The test group was made up of 12 samples coated with light-cured resin surface treatment agent and the left samples as control group were treated with no-coating agent after tooth whitening. Then the two groups were divided into two subgroups which were soaked in distilled water and tea for aging test respectively. The color differences (ΔE) which provided comparative values for statistical analysis was recorded at 1, 3, 5, 7, 14, 21, 28, 35 and 42 days after the aging test. The enamel surface microstructure of the samples was observed before and after bleaching, after resin agent coating, and 28 days after the aging test.RESULTS AND CONCLUSION: (1) Results from color differences observation: there was no significant difference between samples soaked in distilled water before and after whitening treatment (P > 0.05). Similarly, there was no statistical difference between test group and control group soaked in distilled water (P > 0.05). However, after soaking in tea, the color differences in the test group at 1-42 days showed statistically significant differences from those in the control group (P < 0.05). (2) Results from scanning electron microscope observation: after the tooth whitening producers, the enamel surface was damaged in the presence of cavities. After coated with resin surface treatment agent, the enamel surface became smooth and had few cavities. After soaking in tea, gradient smooth surface, some crack, inconspicuous flake dyeing color layer decomposition could be seen in the test group while rough surface with big holes and mottled dyeing layer were clearly visible in the control group. All samples soaked in distilled water had only a small amount of block dyeing layer, holes, weaker roughness than those soaked in tea. To conclude, Adper Single Bond 2 Adhesive light-cured resin surface treatment agent could weaken color relapse phenomenon after tooth whitening, achieving a smooth enamel surface and reducing dyeing material adhesion.
RESUMO
BACKGROUND: Most studies suggest tooth whitening can create a coarse enamel surface which is likely to attract exogenous dyeing material and form the phenomenon of color relapse. After dental bleaching procedure, the use of resin surface treatment agent is expected to make the enamel surface smooth and alleviate tooth color relapse. OBJECTIVE: To unravel the efficacy of Adper Single Bond 2 Adhesive on color relapse phenomenon after dental bleaching treatment by cold light (xenon laser) whitening.METHODS: Twenty-four extracted teeth were collected and coated with 35% hydrogen peroxide followed by xenon laser whitening. The test group was made up of 12 samples coated with light-cured resin surface treatment agent and the left samples as control group were treated with no-coating agent after tooth whitening. Then the two groups were divided into two subgroups which were soaked in distilled water and tea for aging test respectively. The color differences (ΔE) which provided comparative values for statistical analysis was recorded at 1, 3, 5, 7, 14, 21, 28, 35 and 42 days after the aging test. The enamel surface microstructure of the samples was observed before and after bleaching, after resin agent coating, and 28 days after the aging test.RESULTS AND CONCLUSION: (1) Results from color differences observation: there was no significant difference between samples soaked in distilled water before and after whitening treatment (P > 0.05). Similarly, there was no statistical difference between test group and control group soaked in distilled water (P > 0.05). However, after soaking in tea, the color differences in the test group at 1-42 days showed statistically significant differences from those in the control group (P < 0.05). (2) Results from scanning electron microscope observation: after the tooth whitening producers, the enamel surface was damaged in the presence of cavities. After coated with resin surface treatment agent, the enamel surface became smooth and had few cavities. After soaking in tea, gradient smooth surface, some crack, inconspicuous flake dyeing color layer decomposition could be seen in the test group while rough surface with big holes and mottled dyeing layer were clearly visible in the control group. All samples soaked in distilled water had only a small amount of block dyeing layer, holes, weaker roughness than those soaked in tea. To conclude, Adper Single Bond 2 Adhesive light-cured resin surface treatment agent could weaken color relapse phenomenon after tooth whitening, achieving a smooth enamel surface and reducing dyeing material adhesion.
