Randomization and blinding
Participants were randomized to one of the three groups by a research assistant (NSMZ) using a computerized-generated table. A balanced randomly permuted block of 3 and 6 was used to avoid unequal numbers between the groups. To conceal assignment, an opaque sequentially numbered envelope containing the allocated intervention arm was opened at the baseline visit to allocate the respective participant into one arm of the study. One principal examiner (NFA) was responsible for the clinical evaluations and was blinded to the intervention groups throughout the study. Each participant was identified by a code. Although the blinding of participants was not possible, they were not allowed to disclose the oral hygiene tool they used to the examining dentist.