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Objective To evaluate the clinical effect of Wy 10 whitening combined with enamel microabrasion on bleaching dental fluorosis.Methods Forty patients with dental fluorosis were in-cluded and divided into two groups (20 each):group A was treated with Wy 10 whitening and enamel microabrasion,and group B only with Wy 10 whitening.Efficacy was measured according to the Vita classical shade guide before and after treatment.Sensitivity between groups was also tested.Results The effective rate of group A was significantly higher than that of group B (x2 =5.096,P＜0.05).The sensitive rates were 20.0％ (4/20) and 15.0％ (3/20) in group A and group B,respectively.No significant difference was found between the two groups in sensitivity (P＞0.05).Conclusions Wy 10 whitening combined with enamel microabrasion is an effective and safe method for bleaching dental fluorosis.
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<p><b>OBJECTIVE</b>To investigate the effect of different length and diameters on the stability of mini implant and to select optimal length and diameter using continuous variation of parameters.</p><p><b>METHODS</b>To perform 3-dimensional finite element analysis, finite element models of a maxilla, and mini implants with length of 6-12 mm and diameters of 1.2-2.0 mm were generated. Load of two different forces were applied to the head of mini implant. One type was horizontal force (HF), the other was composite force (CF). The maximum equivalent stress (Max EQV) in maxilla and the maximum displacement (Max DM) of mini implant were evaluated.</p><p><b>RESULTS</b>The Max EQV in maxilla and Max DM of mini implant decreased as length and diameter increased. When length was more than 9 mm, the evaluation indexes were small and had a less change. Datas indicated that diameter played a more important role in reducing target, and was a more effective parameter in reducing Max EQV when CF was loaded.</p><p><b>CONCLUSION</b>From biomechanical point of view, the choice of the length should not be more than 9 mm. When CF is loaded using the mini implant, diameter exceeding 1.2 mm are optimal design for mini implant.</p>
Subject(s)
Humans , Dental Implants , Dental Stress Analysis , Finite Element Analysis , Maxilla , Stress, MechanicalABSTRACT
Background Visual electrophysiology is a sensitive index for the evaluation of visual function.It has an important value in the assessment of traumatic optic neuropathy.Rabbit is an ideal animal model of traumatic optic neuropathy,and it is simple for the record of flash visual evoked potential(F-VEP)in rabbits.ObjectiveThe present study is to establish the animal model of traumatic optic neuropathy with or without lens injury and observe the repairing procedure using F-VEP. MethodsModels of traumatic optic neuropathy associated with lens injury were established in the right eyes and only traumatic optic neuropathy were created in the left eyes of 64 healthy SPF Chinese white rabbits using fluid percussion brain injury device(FPI).F-VEP was recorded based on the Proposal of International Visual Electrophysiology on 1,2,4,7,10,14,21,28 days after injury of optic nerves.Experimental animals were sacrificed in above time points for the histopathological examination.Macrophages were labeled by ED-1 antibody and survival retinal ganglion cells (RGCs)were stained by Nissl method.Results At the first day after injury,the latencies of P_(100) in both group were longer,and the amplitudes of P_(100) in both group were lower than before injury,showing statistically significant differences among different time points(P<0.05),but no significant difference was seen between the two groups(P>0.05).The duration of latency in traumatic optic neuropathy associated with lens injury group was shorter than that in only traumatic optic neuropathy group(P<0.05).The restore of latency in traumatic optic neuropathy associated with lens injury group was much faster than that in only traumatic optic neuropathy group(P<0.05).The numbers of macrophages were significantly increased and numbers of survival RGCs were considerably decreased with lapse of injury time (P<0.05).The abnormalities of VEP P_(100) and RGCs were obviously improved in 28 days after injury in both groups. ConclusionThis animal model can be established successfully by FPI.The result of retinal histopathological examination confirms F-VEP findings in this model.
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Objective Previous study showed that the histopathological basis of visual function damage caused by optical nerve injury is apoptosis of retinal ganglion cells(RGCs). This procedure is regulated by P53, bax and caspase 3 genes. Present study aimed to observe the expression of bax, P53 and caspase 3 mRNA in RGCs after traumatic optic nerve damage in the rats by SYBR green I fluorescence quantitative PCR method. Methods The animal model of optic nerve injury was established in the right eyes of 56 adult Wistar rats by a fluid percussion brain injury device (FPI) . Animal were killed on days 1, 3, 5, 7, 9, 14, 28 days separately after injury. Other 16 Wistar rats were divided into normal control group and sham operation group. The total RNA was isolated from rat fresh retina tissue by Trizol method and was treated by reverse transcription to cDNA using 01igo(dt) 18 as primer and then amplified. The target fragments of bax, P53 and caspase 3 cDNA were linked with carrier pTZ57 R/T to construct recombined plasmids which were transformated to E. Coli DH5α by T/A clone method. Recombined plasmids were extracted with alkaline lysis method and the plasmids were selected in white colonies by ampicillin screening, EcoR I restrictive enzyme analysis, and their specificity was evaluated using DNA sequencing. The standard curves were created by plasmid DNA and the precise expression level of target genes in samples were determined using software. The results were expressed as the ratios of target gene mRNA to GAPDH mRNA. Results The standard curve drawn by pTZ57R/T and target gene presented a good linear tendency with the higher sensitivity and specificity. The expression of P53 and bax mRNA began to increase on the third day after the injury of optic nerve and peaked on the fifth day and started to decline on the seventh day. The expression of caspase 3 mRNA increased from the fifth day through the ninth days after injury and declined on the fourteenth day. The significant differences were found in the expression of P53, bax and caspase 3 between model group and control group (P ＜ 0. 05) . Conclusion The pro-apoptotic protein P53, bax and caspase 3 play an important role in RGCs apoptosis.