| OBJECTIVEThe purpose of the present study was to investigate the change of organic acid composition of plaque in multi - bracket fixed treatment, and to study the relationship between fixed orthodontic treatment and the change of caries activity (CA). Effective Capillary Electrophoresis was used to measure the amount of organic acid before and 1 month and 3 month after bonding edgewise appliance. The present study was designed to compare the amount of organic acid in three periods, and a new method, which could evaluate the change of CA correctly in fixed patients, might be founded.METHODS40 patients in general health, 17 male, 23 female, whose age ranged from 11 to 16 years, were selected to participate in this study. All subjects, who hadn't dental flurosis and were DMFS < 10 in permanent dentition, demonstrated good oral hygiene and were scheduled to undergo orthodontic treatment. Samples of plaque fluid were collected before, 1 month and 3 months after the placement of edgewise appliance in each subject. Before collection, the patients were told to stop eating anything after brushing the teeth for no less than 2 hours. When collecting samples, the subjects were asked to rinse with 10% cane - sugar solution for 1 minute, then the collection sites were isolated with cotton rolls and gently air dried with an syringe to minimize contamination by salivary. The plaque fluid of all teeth except lower incisors was collected after 7 minutes, andput in a centrifuged tube, stored in ice, then taken to laboratory in two hours. The samples were centrifuged at 4t (15000r/min, 15min). The supernatant which was plaque fluid ,was taken 1 l out, and mixed with 100 jxl double distilled water in the centrifuged tube, then stored at -70 until laboratory analysis.Effective Capillary Electrophoresis ( Unimicro Technologies, inc. Capd 10322) was carried out to measure the amount of such organic acids as lactic acid, methyle acid, acetic acid, propyl acid, butyric acid and amber acid. Ou-artzose capillary tube with 57cm long and 75 jjun inner diameter was made in Hebei, Yongnian optic fibre factory. The concentration of organic acids were determined by applying 20 1 diluent of each sample to 5 l 0 - phthalic acid of the buffer by VUV - 22, if the following conditions were fulfilled;(1)vacuum injection; 10seconds(2)separated voltage: 20kv,(3)separated time; 7min.(4)separated temperature: 20 C.(5)the buffer was consisted of 10mmol/l O - phthalic acid and 0. 5mmol/l tetradecyltrimethyl - ammonium bromides(TTAB) ; PH =5.7.RESULTAll kinds of organic acids were separated in 6 minute. Compared with before treatment, the amount of organic acids including lactic acid both 1 month and 3 month after placing edgewise appliance were no significance by t - test ( p >0.05).CONCLUSIONIn this study, compared with pre - treatment, the amount of lactic acid had no significant change in plaque fluid post - treatment . It indicated that the reason that individuals with fixed appliances were more prone to tooth decay was not the change of the ability of producing acids in dental plaque.There was a difference between this study and the previous studies, which suggested that CA increased dramatically in fixed treatment by other method to determine the ability of producing acids in dental plaque. In fact, however, this in vivo study has shown that the oral caries was such a complicated environment that the CA in individuals with fixed appliances was not evaluated by a single factor. |
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