Effects Of Three Orthodontic Retainers On Periodontal Pathogens And Periodontal Parameters:A Randomized Controlled Trial

Objective:The objective of this study was to compare and evaluate the changes of periodontal pathogens and periodontal status in three orthodontic retainers,namely,vacuum-formed retainer,Hawley retainer,and lingual fixed retainer,within 6 months of wearing them,so as to provide theoretical basis for clinical selection and application.Whether the use of orthodontic retainer can restore periodontal tissue after removal of fixed appliance.Methods:Forty-eight patients who underwent orthodontic treatment with ordinary metal brackets were randomly divided into 3 groups with 16 patients in each group: VFR group,HR group,LR group。Saliva samples were collected at the time of debonding(T0),one month later(T1),three months later(T2)and six months later(T3).Porphyromonas gingivalis(Pg)and Aggregatibacter actinomycetemcomitans(Aa)were quantitatively analyzed by real-time PCR.At the same time,gingival index(GI),plaque index(PLI)and probing depth(PD)were measured at these four time points to observe the changes of periodontal state.SPSS20.0 software was used to analyze the data,and P < 0.05 was considered statistically significant.Results:Compared with baseline T0,Pg and Aa as well as three periodontal parameters were significantly decreased in the three groups one month after wearing the retainer(P < 0.05).From TI to T2,porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were stable in the three groups(P > 0.05).In Aa of T3,differences were found among the three groups,Hawley group was significantly better than VFR group and HR group(P < 0.05).In Pg of T3,differences were found among the three groups,Hawley group was significantly better than VFR group and HR group(P < 0.05).From T1 to T2,GI,PLI and PD of the three groups tended to be stable(P > 0.05),and differences were found in T3.Differences were found in T3,and GI,PLI and PD in VFR group showed an increasing trend in the three groups(P <0.05).The PLI and PD values at T3 were statistically different,and the Hawley group was lower than the lingual group and the VFR group(P < 0.05).The contents of porphyromonas gingivalis and Actinobacillus concomitant had no significant correlation with the depth of periodontal exploration.Conclusion:Regardless of which retainer was used,the periodontal condition improved significantly after the removal of the metal brackets.From the perspective of porphyromonas gingivalis and Actinobacillus concomitatus,as well as periodontal clinical parameters,Hawley retainer was superior to clear pressure membrane retainer and lingual fixation retainer after 6 months of wear.There was no significant correlation between the contents of porphyromonas gingivalis and Actinobacillus actinobacillus with periodontal probing depth.