Fluorescence-aided identification technique (FIT) in retainer removal : Effects on enamel loss, composite residue,...

The aim of this study was to investigate the difference in enamel loss, composite residue, and time during removal of fixed orthodontic retainers using ultraviolet (UV) light compared to standard white light.

A nickel-chromium retainer was bonded to 4 bovine teeth using a fluorescence-modified composite (Aligner Flow Composite, Voco, Cuxhaven, Germany); 20 models were created. In a split-mouth design, 2 teeth per retainer were removed using standard white light (non-FIT) and 2 teeth using the fluorescence-aided identification technique (FIT) with UV light. Removal time was recorded for each tooth. Intraoral and optical coherence tomography (OCT) scans were taken of the tooth before bonding (T0) and after retainer removal (T1). The intraoral scans were analyzed using the software Avizo to quantify enamel loss (T0-T1) and composite residue (T1-T0). The OCT scans were evaluated using a dichotomous scoring system for enamel loss and a four-point scoring system for composite residue.

There was no significant difference in removal time for the two groups. The overlay of intraoral scans showed significantly less enamel loss in area (39.35 ± 39.98 mm² vs. 65.44 ± 58.11 mm², p = 0.0235) and volume (3.41 ± 6.15 mm³ vs. 8.86 ± 11.65 mm³, p = 0.0116), as well as less composite residue in area (8.22 ± 16.04 mm² vs. 30.87 ± 49.65 mm², p = 0.0083) and volume (0.41 ± 0.87 mm³ vs. 2.34 ± 3.94 mm³, p = 0.0037) in the FIT group compared to standard white light. While OCT scans showed no significant difference in enamel loss, it proved that the amount of composite residue was significantly less in the FIT group compared to the standard light controls (5.88 ± 10.54 vs. 22.66 p = 0.0072).

Although the FIT method does not reduce the removal time of orthodontic fixed retainers, it has been shown to be beneficial in preserving enamel and leaving less composite residue.