A Study On The Influence Of Lingual And Labial Brackets Upon Affinity Of Plaque

The application of Orthodontic fixed appliances can induce the changing of the oral inner environment, which could destroy the dynamic balance of the ecological tooth plaque system, and furthermore stimulate the generation and the growth of nosogenetic bacteria. All these would lead to adverse impact on the teeth and periodontal tissues.At present, it is rare within China to report the study on the application of the lingual fixed appliance, and comparative research about the impact on the oral micro-environment and the adhesion of the plaque between the buccal and lingual fixed appliances. And it is the same abroad.Objective: The purpose of this research is to make clear about the differences between the two different appliances for both the patients and orthodontists and direct the method choosing in daily orthodontic practices, via lab research and clinical comparative study about the impact on the adhesion of the plaque between buccal and lingual fixed appliances.Methods: 40 buccal brackets and 40 lingual brackets were used inthe experiment, which were both manufactured by Ormco Co. in the U.S. each type of the brackets were divided into 10 groups, with 4 brackets in every single group. For all groups, the samples were immersed into a streptococcus mutans solution for 6 hours. Then each sample was immersed in both at 37°C for 24, 48 and 72 hours respectively to measure the adherence of the streptococcus mutans to these samples by plate cultivation counts. In the clinic study, 5 volunteers were chosen, who were in good oral hygiene and healthy with their teeth and periodontal tissues. And all their first premolars were adhered with buccal and lingual brackets respectively. So, totally 20 buccal and 20 lingual brackets were applied in this trial. Before the placement of the brackets, the supra- and sub-gingival plaques on the buccal and lingual surfaces of the first premolars were assessed by Gram staining bacteria smear. The observed values were used as the baseline records. After placement, the same processes were carried out to gain respective values at 1 week, 3 week, 5 week, and 8 week. The bacteria captured were counted by the categories as Gram Positive coccus, Gram Negative coccus, Gram Positive bacillus, and Gram Negative bacillus.Results: The lab experiments showed that there were no significant differences in the adhesion of streptococcus mutans after the placementof the brackets on the buccal and the lingual surfaces. Both the different methods showed the increasing trend of the adhesion of streptococcus mutans following the time elapse. The clinic study showed that the values of the Gram Positive bacteria increased as time went by;but the values of the Gram Negative bacteria decreased in both the buccal and the lingual supragingival plaques. On the contrary, it was opposite for the subgingival plaques that the values of the Gram Positive bacteria decreased and the values of the Gram Negative bacteria increased. There were no significant differences in the influences on the bacteria constitutes of the supragingival and subgingival plaques between the buccal and the lingual orthodontic fixed appliances at different stages after placement. Conclusions:1. Although there are apparently different figures between the buccal and the lingual orthodontic fixed appliances, there is significant difference in the adhesion of streptococcus mutans. The application of the different appliances can result in the increasing adhesion of streptococcus mutans following the time.2. After the placement of both the buccal appliances and lingual appliances, the pathogenicity of the supragingival plaquesincreased.3. After the placement of both of the buccal appliances and lingual appliances, the possibility for the subgingival plaques to develop periodontal disease.4. There is no significant difference between the two methods in the conversion process of the plaques into nosogenetic bacteria.Based on all above, whatever the type of the orthodontic fixed appliances are chosen to utilize, the buccal or the lingual, it is necessary to develop the methods to control and prevent the plaques, so as to keep the patients in good health with their teeth and periodontal tissues.