Randomization and allocation concealment
HT, tooth
The teeth were allocated to two parallel arms: the RC and HT groups. A sequence of random numbers was generated by an external researcher, considering the city as strata in blocks of 4 or 6, obtained from www.sealedenvelope.com. The group allocation was concealed in sealed, numbered opaque envelopes, opened by the operators only at the time of intervention. The experimental unit in the study was the tooth, and only one tooth per patient was included. In case where participants had more than one eligible tooth, each tooth meeting the inclusion criteria was assigned a unique number. These numbers were written on paper, folded, and placed in an opaque envelope. An independent dentist, not involved in the research, was responsible for selecting one envelope containing the tooth number to be included in the study.