Loay Leghrouz, Manasi R. Khole, Christian H. Splieth, Julian Schmoeckel

• Introduction: Proper tooth brushing is a complicated process for children. Therefore, the aim of this study was to investigate the effect of differential learning to improve tooth brushing in children. Methods: In this prospective, controlled, single-blinded, randomized clinical trial, 58 children between 3 and 8 years of age (mean: 5.7 ± 1.5 years; 29 female) were randomly assigned to test or control group through the child’s self-drawing of an unlabeled envelope from a box. All children received oral hygiene instructions and information in these sealed envelopes and were asked to follow the corresponding instructions at home for 28 days. Children in the test group received instructions with exercises using the differential learning method, whereas the children in the control group received the usual tooth brushing instructions. Results: At baseline and planned follow-ups after 4 and 12 weeks, plaque and gingival indices (QHI, PBI) were recorded in both groups by 2 calibrated and blinded investigators. At baseline, there were no significant differences between the test and control groups regarding plaque and gingival indices (QHI: 4.1 ± 0.5 vs. 4.1 ± 0.4; p = 0.7; PBI: 0.6 ± 0.3 vs. 0.6 ± 0.3; p = 0.7). At the 1st and 2nd follow-up, both groups showed improved oral health indices, but there was an overall better improvement in the test group. While the difference in gingival indices was statistically significant in the 1st recall (PBI/test: 0.1 ± 0.2 vs. control: 0.3 ± 0.2; p < 0.001), the difference in plaque indices was not (QHI/test: 2.1 ± 0.9; control: 2.6 ± 0.9; p = 0.07). At the 2nd recall (mean week = 19.5 weeks), the test group showed statistically significant and clinically relevant better oral health indices than the control group (2nd recall, QHI/test: 2.1 ± 0.9 vs. control: 3.2 ± 1; p < 0.001; PBI/test: 0.1 ± 0.2 vs. control: 0.5 ± 0.2; p < 0.001). Conclusion: In conclusion, differential learning leads to oral hygiene improvement in children with high caries risk and initially poor oral hygiene, which was superior to the conventional learning method through repetition in the medium term.