Oral diseases can be greatly controlled by reducing the microbial load in the oral cavity and this can be achieved by maintaining proper oral hygiene. Tooth brushes are the most commonly used oral hygiene aid to promote oral health and prevent dental diseases. The insertion of fixed appliances alters the oral microbiological profile, thus increasing the risk for caries and gingivitis considerably. To assess the microbial growth of S. Mutans and Lactobacillus between and among the brushes. A Hospital setting and Randomized Control study design Methods: A total of 56 (MB) patients aged 16-26 years received a toothbrush [Regular soft bristle design (group-A) and Orthodontic bristle design (group B)], A sterile gamma radiated pouch and checklist was distributed to each participant. After 2 weeks period the brushes were collected and placed in 5ml saline solution (0.05 g Sodium Chloride). The suspension was incubated on selective agar plates and the amount of Streptococcus mutans and lactobacilli for each brush head was assessed. The retention of S. Mutanswas found to be higher in group A, as compared to group B and was found to be statistically more significant between the two groups (P< 0.001). The retention of Lactobacillus was also found to be higher in group A, as compared to group B and was found to be statistically significant between the groups (P= 0.001). However, there was no significant difference (P= 0.101) observedamong the microbial growth of S. Mutans and Lactobacillus in two bristle designs. Regular soft bristle design had a higher microbial load than those of subjects using orthodontic bristle design, a more frequent replacement of toothbrushes during t treatment may be advisable. Due to significant differences between the two bristle designs, the orthodontic toothbrush is recommended for patients undergoing orthodontic t appliances.