Is Caries in the Early Mixed Dentition Associated with Caries Development during Orthodontic Treatment?

Objective: To investigate if caries in the pre-treatment early mixed dentition is associated with caries development in the permanent dentition during orthodontic treatment. Material and Methods: We included 41 consecutive patients (29 girls, 12 boys) with a pre-treatment documentation in the mixed (mean age 9.4 years) and a post treatment documentation in the permanent dentition (age 14.9 years) (two-phased treatment time 4.5 (±1.6) years). The DMFT/S indices were calculated. High-risk and low-risk groups were defined according to dmfs + DMFS score before treatment. Results: Initial dmft/s + DMFT/S (SD) was 5.15 (3.60) and 8.32 (6.64); final DMFT/S was 2.76 (2.84) and 3.01 (3.20). The missing (because of decay) second deciduous molars were most powerfully associated with caries increment during treatment, showing significant correlations to second premolars (r = 0.47, p = 0.003), while fillings on second deciduous molars seem to influence the prevalence of fillings on permanent molars (r = 0.44, p = 0.001). The increment at surface level was 2.01 (2.61) in the whole sample and 2.60 (3.81) in the high-risk group (4 boys, 6 girls). Compared to the low-risk group (10 girls), post-treatment caries experience was significantly higher in the high-risk group (p = 0.029). Boys were more at risk than girls (p = 0.005). Conclusions: Children with elevated caries experience in the early mixed dentition are exposed to higher caries risk during orthodontic treatment. Thus, in prevision of treatment, caries should already be assessed in the mixed dentition, so that an extended prophylaxis program can be initiated.