Caries lesions after orthodontic treatment followed by quantitative light-induced fluorescence: a 2-year follow-up

The aim of this study was to monitor, by means of quantitative light-induced fluorescence (QLF), the natural behaviour of white spot lesions detected immediately after orthodontic treatment and 2 years post-treatment. The buccal tooth surfaces of 51 subjects (>or=12 years), 24 males and 27 females, were examined with QLF for the presence of caries immediately after debonding (T0), and 6 weeks (T1), 6 months (T2), and 2 years (T3) thereafter. The fluorescence loss [Delta F (per cent)] and area [A (mm(2))] of any lesions were determined using dedicated software. The lesion development and influence of gender were determined by a general linear model (Friedman repeated-measures analysis and two-way repeated-measures analysis of variance). Using QLF, 370 carious surfaces were recorded at T0. During the study, 19 lesions were lost from QLF analysis of which 16 lesions (Delta F(0)=7.6-39.2 per cent) in two subjects were restored and three teeth with lesions were extracted or crowned. This resulted in 351 lesions that were included in this study with a median Delta F at T0 of 8.5 per cent (quartiles 6.6 per cent; 11.9 per cent). The lesions varied from incipient (Delta F<10 per cent, n=227) to advanced (Delta F>25 per cent, n=6). Overall, the lesions showed improvement between T0 and T2 (P<0.01) but no further significant improvement at T3. Thirty-five lesions became significantly worse after 2 years. The majority of lesions (n=171) were considered to be stable, and 145 lesions improved significantly of which only 10 lesions improved to such an extent that they disappeared. White spot lesions developed during orthodontic treatment have very limited ability to improve after appliance removal. Further research to investigate the potential of preventive measures to enhance lesion improvement is necessary.