Sample size and randomization
Based on previous studies, a sample size of 60 participants was determined to be sufficient to meet the power of 80% with a significance level of 0.05.The patients were randomly allocated to two groups using a stratified block randomization method: the control and probiotic groups. The randomization was conducted with a block size of 4; each block contained four patients. The randomization process was carried out by a dental assistant who was not involved in the assessments or treatments to maintain blinding of the participants and examiners throughout the study.