Variations of the Plaque Index in Four Timelines during 12 Months in Patients with Two Models of Fixed Retainers after Orthodontic Treatment is Finished

Abstract

Background: Fixed retainers are retention tools bonded on the lingual side of the frontal teeth to prevent relapse after orthodontic treatment is finished. While stability remains the biggest concern, periodontal response remains the subject of discussion. This study aimed to compare plaque index (PI) levels on the lingual side of the lower dental arch in the inter-canine region after bonding two different models of fixed retainers.Methods and Results: The study included 60 subjects aged 16-25 who finished orthodontic treatment. Thirty subjects got flat fixed retainer (FFR), and 30 other subjects got round fixed retainer (RFR) bonded in the lower six frontal teeth on the lingual side. Adapted PI was recorded and photographed at four time points (3, 6, 9, and 12 months). Three months after the intervention, there were no significant differences between the FFR and RFR related to the PI value (P=0.363). PI was significantly lower in the FFR group than in the RFR group 6, 9, and 12 months after the intervention (P<0.004, P=0.004 and P=0.001, respectively).Conclusion: Bonded fixed retainers, in general, cause increased plaque formation and make oral hygiene routines more difficult.